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Our Vampiric Brains

1100 words

Much has been written in the scientific literature on our brain size increase, which has doubled in the timespan of about 3 million years. It is assumed that our brains became bigger so we could become smarter. However, recent data shows that the amount of blood our brains use dramatically increased over the course of human evolution—the amount of blood our brains use increased some 600 percent over the course of human evolution, substantially more than our brain size increase (350 percent).

Seymour, Bosiocic, and Snelling (2016) showed that while there was a 3.5-fold increase in brain size while there was a 6-fold increase in total cerebral blood flow rate. This is due to increased interneuron connectivity, synaptic activity and cognitive function which all depend on the cerebral metabolic rate. This is yet another reason why cooking was so important during our brain evolution. If the brain has a higher metabolic rate, only a high-quality diet will allow it to function. This can only occur if and only if there is a high-quality diet in the first place.

The metabolic intensity of cerebral tissue in our lineage could only be satisfied by a high-quality cooked diet. Clearly, the evolution of the human brain most always goes back to nutrition and the quality of the human diet. Without erectus’ control of fire around 1.5 mya, our brains wouldn’t have been able to grow this big, nor would we have the cerebral blood flow we eventually had. The below picture is figure 1 from the paper. The left slide is Australopithecus Afarensis, the middle is a Neanderthal, and the right is archaic Homo Sapiens.

f1-large

They measured the lumen radius of the internal carotid arteries and were able to deduce that there were large changes in cerebral blood flow in hominin evolution due to the increasing size of the ICAs. Arterial size, blood flow rate and metabolic rate are tightly related. So if there are bigger ICAs, then that hominin had more blood flow to feed a bigger brain. This is clear evidence that as our brain size increased that we needed more blood to feed our growing brain.

Kilroy et al (2013) hypothesize that due to widespread anatomical differences in the anterior cingulate cortex (ACC), PFC and insula and subcortical cortices, those regions must be a “central node of the brain’s network underlying individual differences in intellectual development throughout childhood and adolescence.” Cerebral blood flow in the subgenual/ACC correlates the highest with IQ. They also showed that it’s possible to delineate “where CBF is modulated by IQ.” More blood flow in these regions means a higher IQ. Since the ICAs grew larger over the course of hominin brain evolution to increase intelligence, it’s no surprise that more blood flow to certain parts of the brain is related to higher intelligence in children and adolescents.

Even CBF at rest is correlated with higher intelligence and creativity (Takeuchi et al, 2011). They showed that gray and white matter in the brain is correlated with CBF at rest and significantly and positively with psychometric intelligence. Further, the Raven’s Advanced Progressive Matrices (RAPM) and scores on the creativity test that were administered to the cohort correlated positively with white matter and cerebral blood flow. They also noticed that there was an association between negative mood and increased cerebral blood flow. Grey and white matter CBF at rest were both correlated with the RAPM and the creativity test administered. This is yet more evidence that blood flow to certain parts of the brain dictates intelligence (and most likely individual differences in intelligence as well).

The more vampiric a brain is (especially in certain regions), the higher one’s intelligence will be, on average. By looking back at the fossil skulls of our hominin ancestors and the radius of the ICA, we can infer that as hominin evolution ‘progressed’ through time, the ICA radius increased which meant increased blood flow to the brain. This is directly related to brain metabolism and could only be afforded with a high-quality diet which started with the advent of tool-making and the use of fire to cook by erectus. Cerebral blood flood in the anterior cingulate cortex is significantly and positively correlated with IQ. CBF at rest is also correlated with IQ and certain regions of the brain. This shows that a brain with a higher metabolic rate will be, on average, more intelligent than a brain that has a lower one. The current data on intelligence and CBF points to increased blood flow in certain parts of the brain is related to higher levels of intelligence. This does make sense, as our blood flow to the brain increased by 600 percent over the course of human evolution. So, in a way, we can say that along with our brain size increasing for expertise capacity (which was most definitely needed over the course of hominin evolution) (Skoyles, 2009) along with more cerebral blood flow due to larger arteries and a higher metabolic rate.

This does make sense, as our blood flow to the brain increased by 600 percent over the course of human evolution. So, in a way, we can say that along with our brain size increasing for expertise capacity (which was most definitely needed over the course of hominin evolution) (Skoyles, 2009) along with the need for more blood to the brain to increase intelligence (as blood will also shuttle oxygen to the brain). This is yet another reason why our not-so-special brains are remarkable compared to the rest of the animal kingdom—the one variable that gives us our cognitive superiority over other animals is the ability to cook and use fire. A lot of our physiologic, anatomic and brain evolution can be explained simply as: no cooking, fire, and meat, no big brains (and as a consequence, everything you see around you today would not be here), and the only thing that can drive such a metabolically demanding brain is cooking and eating high-quality foods. The outstanding number of neurons crowded into our cerebral cortex along with much blood our vampiric brain guzzles explains our cognitive superiority over other animals.

References

Kilroy, E., Yan, L., Wang, D. J., Dapretto, M., Mendez, M. F., Liu, C. Y., & Kim, Y. C. (2011). Relationships between Cerebral Blood Flow and IQ in Typically Developing Children and Adolescents. Journal of Cognitive Science,12(2), 151-170. doi:10.17791/jcs.2011.12.2.151

Seymour, R. S., Bosiocic, V., & Snelling, E. P. (2016). Fossil skulls reveal that blood flow rate to the brain increased faster than brain volume during human evolution. Royal Society Open Science,3(8), 160305. doi:10.1098/rsos.160305

Dr. John R. Skoyles (1999) HUMAN EVOLUTION EXPANDED BRAINS TO INCREASE EXPERTISE CAPACITY, NOT IQ. Psycoloquy: 10(002)

Takeuchi, H., Taki, Y., Hashizume, H., Sassa, Y., Nagase, T., Nouchi, R., & Kawashima, R. (2011). Cerebral Blood Flow during Rest Associates with General Intelligence and Creativity. PLoS ONE,6(9). doi:10.1371/journal.pone.0025532

Neurons By Race

1100 words

With all of my recent articles on neurons and brain size, I’m now asking the following question: do neurons differ by race? The races of man differ on most all other variables, why not this one?

As we would have it, there are racial differences in total brain neurons.In 1970, an anti-hereditarian (Tobias) estimated the number of “excess neurons” available to different populations for processing bodily information, which Rushton (1988; 1997: 114) averaged to find: 8,550 for blacks, 8,660 for whites and 8,900 for Asians (in millions of excess neurons). A difference of 100-200 million neurons would be enough to explain away racial differences in achievement, for one. Two, these differences could also explain differences in intelligence. Rushton (1997: 133) writes:

This means that on this estimate, Mongoloids, who average 1,364 cm3 have 13.767 billion cortical neurons (13.767 x 109 ). Caucasoids who average 1,347 cm3 have 13.665 billion such neurons, 102 million less than Mongoloids. Negroids who average 1,267 cm3 , have 13.185 billion cerebral neurons, 582 million less than Mongoloids and 480 million less than Caucasoids.

Of course, Rushton’s citation of Jerison, I will leave alone now that we know that encephilazation quotient has problems. Rushton (1997: 133) writes:

The half-billion neuron difference between Mongoloids and Negroids are probably all “excess neurons” because, as mentioned, Mongoloids are often shorter in height and lighter in weight than Negroids. The Mongoloid-Negroid difference in brain size across so many estimation procedures is striking

Of course, small differences in brain size would translate to differences differences neuronal count (in the hundreds of millions), which would then affect intelligence.

Moreover, since whites have a greater volume in their prefrontal cortex (Vint, 1934). Using Herculano-Houzel’s favorite definition for intelligence, from MIT physicist Alex Wissner-Gross:

The ability to plan for the future, a significant function of prefrontal regions of the cortex, may be key indeed. According to the best definition I have come across so far, put forward by MIT physicist Alex Wissner-Gross, intelligence is the ability to make decisions that maximize future freedom of action—that is, decisions that keep most doors open for the future. (Herculano-Houzel, 2016: 122-123)

You can see the difference in behavior and action in the races; how one race has the ability to make decisions to maximize future ability of action—and those peoples with a smaller prefrontal cortex won’t have this ability (or it will be greatly hampered due to its small size and amount of neurons it has).

With a smaller, less developed frontal lobe and less overall neurons in it than a brain belonging to a European or Asian, this may then account for overall racial differences in intelligence. The few hundred million difference in neurons may be the missing piece to the puzzle here.Neurons transmit information to other nerves and muscle cells. Neurons have cell bodies, axons and dendrites. The more neurons (that’s also packed into a smaller brain, neuron packing density) in the brain, the better connectivity you have between different areas of the brain, allowing for fast reaction times (Asians beat whites who beat blacks, Rushton and Jensen, 2005: 240).

Remember how I said that the brain uses a certain amount of watts; well I’d assume that the different races would use differing amount of power for their brain due to differing number of neurons in them. Their brain is not as metabolically expensive. Larger brains are more intelligent than smaller brains ONLY BECAUSE there is a higher chance for there to be more neurons in the larger brain than the smaller one. With the average cranial capacity (blacks: 1267 cc, 13,185 million neurons; whites: 1347 cc, 13,665 million neurons, and Asians: 1,364, 13,767 million neurons). (Rushton and Jensen, 2005: 265, table 3) So as you can see, these differences are enough to account for racial differences in achievement.

A bigger brain would mean, more likely, more neurons which would then be able to power the brain and the body more efficiently. The more neurons one has, the more likely it it that they are intelligent as they have more neuronal pathways. The average cranial capcities of the races show that there are neuronal differences between them, which these neuronal differences then are the cause for racial differences, with the brain size itself being only a proxy, not an actual indicator of intelligence. The brain size doesn’t matter as much as the amount of neurons in the brain.

A difference in the brain of 100 grams is enough to account for 550 million cortical neurons (!!) (Jensen, 1998b: 438). But that ignores sex differences and neuronal density. However, I’d assume that there will be at least small differences in neuron count, especially from Rushton’s data from Race, Evolution and Behavior. Jensen (1998) also writes on page 439:

I have not found any investigation of racial differences in neuron density that, as in the case of sex differences, would offset the racial difference in brain weight or volume.

So neuronal density by brain weight is a great proxy.

Racial differences in intelligence don’t come down to brain size; they come down to total neuron amount in the brain; differences in size in certain parts of the brain critical to intelligence and amount of neurons in those critical portions of the brain. I’ve yet to come across a source talking about the different number of neurons in the brain by race, but when I do I will update this article. From what we know, we can make the assumption that blacks have less packing density as well as a smaller number of neurons in their PFC and cerebral cortex. Psychopathy is associated with abnormalities in the PFC; maybe, along with less intelligence, blacks would be more likely to be psychopathic? This also echoes what Richard Lynn says about Race and Psychopathic Personality:

There is a difference between blacks and whites—analogous to the difference in intelligence—in psychopathic personality considered as a personality trait. Both psychopathic personality and intelligence are bell curves with different means and distributions among blacks and whites. For intelligence, the mean and distribution are both lower among blacks. For psychopathic personality, the mean and distribution are higher among blacks. The effect of this is that there are more black psychopaths and more psychopathic behavior among blacks.

Neuronal differences and size of the PFC more than account for differences in psychopathy rates as well as differences in intelligence and scholastic achievement. This could, in part, explain the black-white IQ gap. Since the total number of neurons in the brain dictates, theoretically speaking, how well an organism can process information, and blacks have a smaller PFC (related to future time preference); and since blacks have less cortical neurons than Whites or Asians, this is one large reason why black are less intelligent, on average, than the other races of Man. 

How Intelligent Were Our Hominin Ancestors?

3000 words

Tl;dr: Two of our most recent ancestors have IQs, theoretically speaking, near ours. This suggests that there were beneficial effects of cultural accumulation and transference. This also lends credence to Gould’s work in Full House, where he writes that “cultural change can vastly outstrip the maximal rate of Darwinian evolution.” Brain size may not have increased for IQ, but for expertise capacity. This is seen in the !Kung, gamblers at the horse track, chess players and musicians. There is both theoretical and empirical evidence that expertise needs large amounts of brain to store “and actively process its informational chunks.” These two studies in combination, in my opinion, shows how important the advent of ‘culture’ was for humans. Tool use got passed down as it gave us fitness advantages, then when Erectus discovered fire, that’s when the game changed. One of the first instances of cultural transference then happened, which set the stage for the rest of human evolution. Looking at it from this perspective, the importance of cultural inheritance and transference cannot be understated. It was due to that ‘behavioral change’ that allowed us all of the advantages we have over our ancestors; we have them to thank for everything we see around us today. For if not for them passing down the beginnings of culture that increased our fitness, individuals would have had to learn things for themselves which would decrease fitness. It’s due to this transference that we are here today.

My recent articles have consisted of what caused our big brains, whether or not there is ‘progress’ in hominin brain evolution, why humans are cognitively superior to other animals, and that the human brain is a linearly scaled-up primate brain (Herculano-Houzel, 2009). Knowing what we know about the human brain and the cellular scaling rules for primates (Herculano-Houzel, 2007), we can infer the amount of neurons that our ancestors Erectus, Heidelbergensis, and Neanderthals had. How intelligent were they? Does the EQ predict intelligence better for non-human primates, or does overall brain weight matter most? If our immediate ancestors had the same amount of neurons as we do, what does that mean for our supposed cognitive superiority over them?

How many neurons did our ancestors have, and what did it mean for their intelligence levels? Herculano-Houzel (2013) estimated the amount of neurons that our ancestors had: Afarensis (35 b), Paranthropus (33 b), to close to 50-60 billion neurons in our species Homo from rudolfensis to antecessor, H. Erectus (62 b), Heidelbergensis (76 b), and Neanderthals (85 b), which is within the range for modern Sapiens. From our knowledge of the average human’s IQ (say, 100) and the total number of neurons the brain has (86 billion), what can we say about the IQs of Erectus, Afarensis, Paranthropus, rudolfensis, antecessor, Heidelbergensis, and Neanderthals?

neuron-and-brain-size

(chart from Herculano-Houzel and Kaas, 2011)

Since Afarensis had about 35 billion neurons we can infer that his IQ was about 40. Paranthropus with about 33 billion neurons had an IQ of about 38. Homo habilis had 40 billion neurons, equating to IQ 46. Erectus with 62 billion neurons comes in at IQ 72., which differs with PP’s estimate by 22 points. (You can see the brain size increase [more on that later] and total neuron increase between habilis and erectus, with an almost 20 IQ point difference. The cause of this is the advent of cooking and the tool-use by habilis, named ‘Handy Man’.) Now we come to a problem. The total number of neurons in the brain of Heidelbergensis, Neanderthals, and humans are about the same.

Heidelbergensis had 76 billion neurons which equates to IQ 88. Neanderthals had about 85 billion neurons, equating to IQ 99. Our IQs are 100 with 86 billion neurons. As you can see, the leap from habilis (who may have eaten meat) to Erectus, a jump of 22 billion neurons and along with it 22. (The rise of bipedalism and tool use, fire, cooking, and meat eating led to the huge increase in neurons in our species Homo.) Then from Erectus to Heidelbergensis was a jump of 14 billion neurons along with an increase of 16 IQ points, then from Heidelbergensis to Neanderthal is an increase of 9 billion neurons, increasing IQ about 11 points. Neanderthals to us is about 1 billion neurons showing a difference of 1 IQ point.

This leads us to a troubling question: did Neanderthals and Hheidelbergensis at least have the capacity to become as intelligent as us? Herculano-Houzel and Kaas (2011) write:

Given that cognitive abilities of non-human primates are directly correlated with absolute brain size [Deaner et al., 2007], and hence necessarily to the total number of neurons in the brain, it is interesting to consider that enlarged brain size, consequence of an increased number of neurons in the brain, may itself have contributed to shedding a dependence on body size for successful competition for resources and mates, besides contributing with larger cognitive abilities towards the success of our species [Herculano-Houzel, 2009]. In this regard, it is tempting to speculate on our prediction that the modern range of number of neurons observed in the human brain [Azevedo et al., 2009] was already found in H. heidelbergensis and H. neanderthalensis, raising the intriguing possibility that they had similar cognitive potential to our species. Compared to their societies, our outstanding accomplishments as individuals, as groups, and as a species, in this scenario, would be witnesses of the beneficial effects of cultural accumulation and transmission over the ages.

If true, this is a huge finding as it echoes what Stephen Jay Gould wrote 21 years ago in his book Full House, as I documented in my article Stephen Jay Gould and Anti-Hereditarianism:

“The most impressive contrast between natural evolution and cultural evolution lies embedded in the major fact of our history. We have no evidence that the modal form of human bodies or brains has changed at all in the past 100,000 years—a standard phenomenon of stasis for successful and widespread species, and not (as popularly misconceived) an odd exception to an expectation of continuous and progressive change. The Cro-Magnon people who painted the caves of the Lascaux and Altamira some fifteen thousand years ago are us—and one look at the incredible richness and beauty of this work convinces us, in the most immediate and visceral way, that Picasso held no edge in mental sophistication over these ancestors with identical brains. And yet, fifteen thousand years ago no human social grouping had produced anything that would conform with our standard definition of civilization. No society had yet invented agriculture; none had built permanent cities. Everything that we have accomplished in the unmeasurable geological moment of the last ten thousand years—from the origin of agriculture to the Sears building in Chicago, the entire panoply of human civilization for better or for worse—has been built upon the capacities of an unaltered brain. Clearly, cultural change can vastly outstrip the maximal rate of natural Darwinian evolution.” (Gould, 1996: 220)

But human cultural change is an entirely distinct process operating under radically different principals that do allow for the strong possibility of a driven trend for what we may legitamately call “progress” (at least in a technological sense, whether or not the changes ultimately do us any good in a practical or moral way). In this sense, I deeply regret that common usage refers to the history of our artifacts and social orginizations as “cultural evolution.” Using the same term—evolution—for both natural and cultural history obfuscates far more than it enlightens. Of course, some aspects of the two phenomena must be similar, for all processes of genealogically constrained historical change must share some features in common. But the differences far outweigh the similarities in this case. Unfortunately, when we speak of “cultural evolution,” we unwittingly imply that this process shares essential similarity with the phenomenon most widely described by the same name—natural, or Darwinian, change. The common designation of “evolution” then leads to one of the most frequent and portentious errors in our analysis of human life and history—the overly reductionist assumption that the Darwinian natural paradigm will fully encompass our social and technological history as well. I do wish that the term “cultural evolution” would drop from use. Why not speak of something more neutral and descriptive—“cultural change,” for example? (Gould, 1996: 219-220)

The implications of the findings of the neuron count in Heidelbergensis and Neanderthals, if true, is a huge finding. Because it implies, as Herculano-Houzel and Kaas say, that “our outstanding accomplishments as individuals, as groups, and as a species … would be witnesses of the beneficial effects of cultural accumulation and transmission through the ages.” I’ve been thinking about this one sentence all week, racking my brain on what it could mean, while thinking about alternate possibilities.

I came across a paper by Dr. John Skoyles titled Human Evolution Expanded Brains to Increase Expertise, Not IQ (saying that around this part of the internet is the equivalent of heresy), in which he reviews studies of people living with microcephaly, showing that a lot of people who have the average brain size of Erectus have average, and even sometimes above average/genius IQs. Yes, microcephaly is correlated with retardation and low IQ, but a significant percentage of individuals inflicted with the disease showed average IQ scores (7 percent overall, 22 percent in 1 subgroup) (Skoyles, 1999). As I’ve documented in the past few days, Erectus was the hominin that learned how to control fire and kicked off the huge spurt in our brain growth. When this increase occurred, brain growth still had to happen outside of the brain, making the baby a fetus for one year after it is born. To achieve its larger brain size, the fetus must have a larger brain before birth, with it increasing postnatally.

The solution to this was to widen the hips of women. This would allow the birth canal to be ‘just right’ in terms of size so the baby could just barely make the squeeze. Physiological differences like this are why there are such huge sex differences in sports. Skoyles (1999) writes:

Research of three kinds suggests that small brained people can have normal IQs: (i) a recent MRI survey on brain size (Giedd et al. 1996), (ii) data on individuals born with microcephaly (head circumference 2 SD below the mean; Dorman, 1991); and (iii) data on early hemispherectomy (the removal of a dysfunctional cerebral hemisphere; Smith & Sugar, 1975; Griffith & Davidson, 1966; Vining et al., 1993).

He also writes that in a sample of  1006 school children, 2 percent (19 students) were found to be microcephalic. Of the 19 microcephalics, only 12 were in districts that did intelligence testing. Of the 12, 7 of them had an average IQ, with one having an IQ of 129. Skoyler even cites a study where a woman’s cranial capacity may have possibly been 760 cc (one the lower end of the range of Erectus brains)!! Her employment was described as ‘semi-skilled’, which Skoyler notes is normal for her ability level. Skoyler also says that Medline shows 21 other studies showing that microcephalic individuals have average IQs.

There is also one incidence of a man having a smaller brain than erectus while having a normal intelligence level, showing no peculiarities or mental retardation. Upon his death, his brain was weighed and they discovered that it weighed 624 grams!

Now, of course, the studies that Skoyler brings up are outliers, but they raise very interesting questions when you think about the supposed link with IQ and brain size. More interestingly, even sudden brain damage will leave a small change, if any, in IQ (Bigler, 1995). Finally, the .35 brain size-IQ correlation needs to be talked about. Let’s be generous and say the correlation is .5, 74 percent of the variance in IQ would still be unexplained (Skoyler, 1999: 8).

Skoyler then says that IQ tests “show very moderate to zero correlations with people’s ability to acquire expertise (Ackerman, 1996; Ceci & Liker, 1986; Doll & Mayr, 1987; Ericsson & Lehmann, 1996; Shuter-Dyson & Gabriel, 1981).” So he says that one’s capacity for expertise isn’t necessarily predicated on their IQ as measured by IQ tests. Skoyler writes:

Hence, whereas nonexpert players see only chess pieces, chess masters see possible future moves and potential strategies. Such in depth perception arises from acquiring and being able to actively use a larger numbers of informational “chunks” in analyzing a problem. The number of such chunks in chess masters has been estimated at 50,000 (Gobet & Simon, 1996). Such information processing chunks take many years to acquire. After reviewing performance in sport, medicine, chess and music, Ericsson and Lehmann (1996) propose that before people can show expertise in any domain they must have performed several hours of practice a day for a minimum of 10-years

So, this ‘expertise capacity’ seems to be a trained—not inherited—trait. He then cites a study on people who’ve spent decades at the daily race track betting on horse races. Cece and Liker (1986) measured the IQs of 12 of the experts, and found that they ranged between IQ 81 and 128 (“four were between 80 and 90, three between 90 and 100, two between 100 and 110 and only three above 120 Table 6”). The authors write: “whatever it is that an IQ test measures, it is not the ability to engage in cognitively complex forms of multivariate reasoning.” Moreover, Skoyler writes, expertise in chess (see Erickson, 2000) and music (see Deutsch, 1982: 404-405) “correlates poorly, or not at all with IQ.”

Now that we know that the capacity to develop expertise isn’t needed in the modern world, what did it mean for our hunter-gatherer ancestors? Looking at some of the few hunter-gatherer tribes left today, we can make some inferences.

The !Kung bushmen use in-depth expert knowledge and reasoning. Just by looking at a few tracks in the dirt, a bushman can infer whether the animal that made the track is sick, whether it was alone, its age and sex. They are able to do this by reading the shape and depth of the track in the dirt. Such skill, obviously, is learned, and those who didn’t have the capacity for expertise would have died out. Further, expertise in hunting is more important than physical ability, with the best hunters being over the age of 39 and not those in their 20s. This can further be seen when the young men go out for hunting. The young men do the physical work while the elder reads tracks, a learned ability.

This, Skoyler writes, suggests that those who had the highest capacity for expertise would have had the best chance for survival. Expertise in hunting is not the only thing that we need expertise for, obviously. The skill of ‘expertise’ translates to most all facets of human life. And over time, the advantages conferred by success with these activities “would result in the natural selection of brains with increased capacity for expertise.” So, even possibly, the success of our expertise could have selected for bigger brains which would have further increased the capacity for our expertise.

Since expertise is linked to the number of brain chunks that a brain can “hold and actively process”, that capacity for expertise “may be related to the number of cortical columns able to specialise neural networks in representing and processing them, and through this to cerebral mass Jerison (1991).” And, in brain scans of expert violinists, they have two to three times as much of their cortical area devoted to their left fingers as nonviolinists. ” This suggests that a strong connection should exist between the capacity for acquiring expertise skills and brain mass.”

I’m, of course, not denying the usefulness of IQ tests. What I’m saying, is that IQ tests don’t test a person’s capacity to learn a skill and become an expert in something. IQ tests, as shown, do not measure expertise capacity. IQ tests, then, don’t test for what was central to our evolution as hominins: expertise capacity. Of course, it’s not only expertise in hunting that led to the selection for bigger brains, and along with it expertise capacity. Obviously, this would hold for other things in our evolution that we can become experts in, from scavenging, to gathering, to language, social relationships, tool-making, and passing on useful skills that would infer an increase in fitness.

IQs for hominins are as follows: Paranthropus: IQ 38 (33 billion neurons); Afarensis: IQ 40 (35 billion neurons); Habilis: IQ 46 (40 billion neurons); Erectus: IQ 72 (62 billion neurons); Heidelbergensis: IQ 88 (76 billion neurons); Neanderthals: IQ 99 (85 billion neurons) and Sapiens: IQ 100 (85 billion neurons). So if Heidelbergensis and Neanderthals had IQs around ours (theoretically speaking), and Erectus had an IQ around modern-day Africans today, what explains our achievements over our hominin ancestors if we have around the same IQs?

Lamarckian cultural inheritance. If you think about when brain size began to increase, it was around the time that bipedalism occurred in the fossil record, along with tool use, fire, cooking, and meat eating. I’m suggesting here today that the beginnings of cultural transference happened with Afaraensis, Habilis, and Erectus. Passing down culture (useful traits for survival back then) would have been paramount in hominin survival. One wouldn’t have to learn how to do things on their own, and could learn from and elder the crucial survival skills they needed. This would have selected for a bigger brain due to the need for a higher expertise capacity, as with a bigger brain there is more room for cortical columns and neurons which would better facilitate expertise in that hominin.

I’m still thinking about what this all means, so I haven’t taken a side on this yet. This is an extremely interesting look into hominin brain size evolution, which shows that big brains didn’t evolve for IQ, but to increase expertise capacity. Though there is an extremely strong possibility that we gained over 20 billion neurons from Erectus due to his cooking, which then capped out our intelligence in our lineage. That would then mean that Neanderthals and Heidelbergensis would have had the capacity for the same IQ as us. One thing I can think of that set us apart 70 kya was the advent of art. That was a new way of transferring information from our hugely metabolically expensive neurons. This was also, yet another way of cultural transference. But what this means in terms of Neanderthal and Heidelbergensis IQ and what it means for our accomplishments since them is another story, which I will return to in the future.

Why Are Humans Cognitively Superior to Other Animals?

1550 words

The past few articles I have written touched on the fact that the human brain isn’t special and is just a scaled-up primate brain, bipedalism, tools, fire, cooking and meat eating had the largest effect on hominin brain evolution, and that, despite seeing a so-called ‘upward trend’ in the evolution of primate brain size, the reverse was occurring. So what makes us cognitively superior to other animals?

The most oft-cited reason why humans are cognitively superior to other animals is that we have the largest EQ compared to other animals. Ours is 7.5, meaning that we have a brain that’s 7.5 times larger than a mammal for our size but only 3.4 times as larger than expected for an anthropoid primate of its body mass (Azevedo et al, 2009). However, in stark contrast to the view of the people who view EQ as the reason why we are cognitively superior to other animals, what separates us in terms of cognitive ability is the difference in cortical neurons compared to other primates.

We humans have the most cortical neurons in our cerebral and prefrontal cortexes, relatively high neuron packing density (NPD), and much more cortical neurons of mammals of the same brain size (Roth and Dicke, 2012). Differences in intelligence across primate taxa best correlate with differences in number of cortical neurons, information processing speed, and synapses. Though, the human brain stands out having a “large cortical volume with a relatively NPD, high conduction velocity and high cortical parcellation.” This is why we are much more intelligent than other primates, due to the amount of cortical neurons we have as well as higher neuron packing density (keep this in mind for later). Encephalization quotient doesn’t explain intelligence differences within species, hence there being a problem with the use of encephalization to as the reason for human cognitive superiority, our Human Advantage, if you will.

Harry Jerison, the originator of the encephalization quotient, came to the conclusion that “human evolution … had been all about an advancement of encephalization quotients culminating in man.” (Herculano-Houzel, 2016: 15) What a conclusion. Just because EQ increased throughout hominin evolution, that means that it was all an advancement of EQs culminating to man. That’s circular logic.

Moreover, the “circular assumption” that higher EQ mean superior cognitive abilities in humans wasn’t founded on “tried-and-true correlations with actual measures of cognitive capacity.” (Herculano-Houzel, 2016: 15)

In second place on the EQ chart is the capuchin monkey coming in with an EQ of 2, which is more than double that of great apes who fall way below 1. That would imply that capuchin monkeys are more intelligent than great apes and outsmart great apes, right? Wrong. Great apes are. Total brain size predicts cognitive abilities in non-human primates better than EQ (Deaner et al, 2007).

Great apes significantly outperform other lineages. (Deaner, Schaik, and Johnson, 2006) Yet they have smaller EQs compared to other less intelligent primates. This is one of the largest problems with the EQ: total brain size is a better predictor of cognitive ability in non-human primates (Herculano-Houzel, 2011). She proposes that the absolute number of neurons, irrespective of brain size or body weight, is a better predictor of cognitive ability than is EQ.

Another problem with the EQ is that it assumes that all brains are made the same, and they aren’t. They scale differently between species. That’s one pretty huge flaw. Scaling is not the same across species, only within certain species. This one fatal flaw in EQ comparing different species of humans is why there is a problem with EQ in assessing cognitive abilities and why total brain size predicts cognitive abilities in non-human primates better than EQ.

Absolute brain size is a much better indicator of intelligence than the encephalization quotient.

So what exactly explains human cognitive superiority over other animals if the most often-used metric—the EQ—is flawed? An enlarged frontal cortex? No, the prefrontal areas in a human brain occupy 29 percent of the mass of the cerebral cortex. Moreover, the prefrontal cortex of humans, bonobos, chimpanzees, gorillas, and orangutans occupies the same 35-37 percent of all cortical volume (Semendeferei et al, 2002). (See also Herculano-Houzel, 2016: 119 and Gorillas Agree: Human Frontal Cortex is Nothing Special). Just because our frontal cortexes are all the same size, doesn’t mean that we don’t have a higher neuron packing density (NPD) than other primates. However, the human brain has the amount of neurons expected for its grey matter volume and total number of neurons remaining in the cerebral cortex; it has the white matter volume expected for amount of neurons; and the white matter volume and number of neurons expected for the number and volume of neurons in the “nonprefrontal subcortical white matter” (Herculano-Houzel, Watson, and Paxinos, 2013). The human prefrontal cortex is no larger than it ‘should’ be.

However, there seems to be a problem with Herculano-Houzel’s (2011) theory that absolute number of neurons predicts cognitive superiority (Mortenson et al, 2014). The long-finned pilot whale has 37,200,000 neurons in its cerebral cortex, more than double that of humans (16 billion). Does this call into question Herculano-Houzel’s (2011) theory on absolute number of neurons being the best case of human cognitive superiority over other animals?

In short, no. Neuron density is higher in humans than in the pilot whale. We have more neurons packed into our cerebral cortex. Their higher cell count is due only to their larger brains. And where it matters: pilot whales have a higher than expected amount of neocortical neurons relative to body weight, although not higher than humans. Herculano-Houzel’s (2011) theory is still in play here. They have big brains and in turn large amounts of glial cells to counter heat loss. So even then, this doesn’t counter Herculano-Houzel’s theory that the absolute amount of neurons dictates overall cognitive superiority.

Moreover, there is the same amount of cortical neurons in mice brains and human brains, with both mice and humans housing 8 percent of their total neurons in the prefrontal cortex. So what accounts for human cognitive superiority in humans compared to other primates? Most likely, the connectivity of the brain.

The connectivity in the brain of humans is not different from other species. The density of gray matter within species is fairly constant within mammalian species (Herculano-Houzel, 2016: 122). If true, then human prefrontal cortex, being nowhere near the largest, wouldn’t have the most synapses in our prefrontal cortex or anywhere else in the brain, and thus these wouldn’t be the largest. So, what does explain the cognitive superiority of humans over other animals in the animal kingdom?

All though all mammals use 8 percent of their total neurons in their prefrontal cortex, there is a differing distribution due to the amount of total neurons in each brain (remember, all brains aren’t made the same. It doesn’t hold for humans, and it especially doesn’t hold across phyla). We have 1.3 billion cortical neurons in our prefrontal cortex, baboons have 230 million, the macaque has 137 million and the marmoset has 20 million (Herculano-Houzel, 2016: 122). Prefrontal neurons are able to add complexity and flexibility, among other associative functions, to behavior while making planning for the future possible. All of these capabilities would increase with the more neurons a prefrontal cortex has (remember back to my article that the seat of intelligence (g) is the prefrontal cortex). So this seems to confirm the past studies showing the seat of intelligence to be the frontal cortex, due to the large amount of cortical neurons it has.

Herculano-Houzel writes the best definition of intelligence she’s ever heard, from MIT physicist Alex Wissner-Gross, which I believe is a great definition of intelligence:

The ability to plan for the future, a significant function of prefrontal regions of the cortex, may be key indeed. According to the best definition I have come across so far, put forward by MIT physicist Alex Wissner-Gross, intelligence is the ability to make decisions that maximize future freedom of action—that is, decisions that keep most doors open for the future. (Herculano-Houzel, 2016: 122-123)

All of the above are the direct result of more neurons in our frontal cortexes compared to other primates, which is why she finds it is the best definition of intelligence she’s ever heard.

Our ‘Human Advantage’ over other species comes down to the number of cortical neurons we have in our prefrontal cortex compared to other primates as well as the most neurons along with the highest NPD in the animal kingdom—which will be matched by no animal. The encephalization quotient has a lot of problems, with overall brain weight being a much better predictor of intelligence (Herculano-Houzel, 2011). Human cognitive superiority comes down to the total amount of neurons in our frontal cortex (1.3 billion neurons—where we will not be beaten) and our cerebral cortexes (16 billion neurons [long-finned pilot whales beat us out by more than double the amount, but we have more neurons packed into our cerebral cortex signifying our higher cognitive abilities). Within primates, total brain size predicts cognitive abilities better than EQ (Deaner et al, 2007).

Human cognitive superiority, contrary to popular belief, is not due to the EQ. It’s due to our NPD and amount of neurons in our frontal and cerebral cortexes that no other animal has–and we will not find another animal like this. This only would have been possible with the advent of bipedalism, tool-making, fire, cooking and meat eating. That’s what drives the evolution of brain size—and our evolution as a whole. Energy. Energy to reproduce, which then produce mutations which eventually coalesce new species.

Is There Progress in Hominin Brain Evolution?

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Tl;dr: The ‘trend’ in the evolution of hominin brain size is only due to diet quality and abundance. If there is any scarcity of food or a decrease in nutritional quality, there will be a subsequent decrease in brain size, as seen with H. floresiensis. Brain size, contrary to popular belief, has been decreasing for the past 20,000 years and has accelerated in the past 10,000. This trend is noticed all over the world with multiple hypotheses put out to explain the phenomenon. Despite this, people still deny that a decrease is occurring. Is it? Yes, it is. It’s due to a decrease in diet quality along with higher population density. If the human diet were to decrease in quality and caloric amount, our brains—along with our bodies—would become smaller over time.

Is there progress in hominin brain evolution? Many people may say yes. Over the past 7 million years, the human brain has tripled in size with most of this change occurring within the past 2 million years. This perfectly coincides with the advent of bipedalism, tool-making, fire, cooking and meat eating. Knowing the causal mechanisms behind the increase in hominin (primate) brain size, is there ‘progress’ to brain size in hominin evolution?

Looking at the evolution of hominin brain size in the past 7 million years, one can rightfully make the case that there is an evolutionary trend with the brain size increase. I don’t deny there is an increase, but first, before one says there is ‘progress’ to this phenomenon, you must look at it from both sides.

Montgomeroy et al (2010) reconstructed the ‘ups and downs’ of primate brain size evolution, and of course, decreases in hominin brain size can’t be talked about without bringing up H. floresiensis and his small brain and body mass, which they discuss as well. They come to the conclusion that “brain expansion began early in primate evolution”, also showing that there have been brain size increases in all clades of primates. Humans only show a bigger increase in absolute mass, with rate of proportional change in mass and relative brain size “having greater episodes of expansion elsewhere on the primate phylogeny”. Decreases in brain size also occurred in all of the major primate clades studied, they conclude that “while selection has acted to enlarge primate brains, in some lineages this trend has been reversed.” The selection can only occur in the presence of adequate kcal, keeping everyone sated and nourished enough to provide for the family, ensuring a woman gets adequate kcal and nutrients during pregnancy and finally ensuring that the baby gets the proper amount of energy for growth during infancy and childhood.

Montgomery et al write:

The branch with the highest rate of change in absolute brain mass is the terminal human branch (140,000 mg/million years). However for rate of proportional change in absolute brain mass the human branch comes only fourth, below the branches between the last common ancestor of Macaques and other Papionini, and the last common ancestor of baboons, mangabeys and mandrills (48 to 49), the ancestral primate and ancestral haplorhine (38 to 39) and the branch between the last common ancestor of Cebinae, Aotinae and Callitrichidae, and the ancestral Cebinae (58 to 60). The rate of change in relative brain mass along the human branch (0.068/million years) is also exceeded by the branch between the last common ancestor of Alouatta, Ateles and Lagothrix with the last common ancestor of Ateles and Lagothrix (branch 55 to 56; 0.73), the branch connecting the last common ancestor of Cebinae, Aotinae and Callitrichidae, and the ancestral Cebinae (branch 58 to 60; 0.074/million years) and the branch connecting the last common ancestor of the Papionini with the last common ancestor of Papio, Mandrillus and Cercocebus (branch 48 to 49; 0.084). We therefore conclude that only in terms of absolute mass and the rate of change in absolute mass has the increase in brain size been exceptional along the terminal branch leading to humans. Once scaling effects with body mass have been accounted for the rate of increase in relative brain mass remains high but is not exceptional.

“Remains high but is not exceptional”, ie, expected for a primate of our size (Azevedo et al, 2009). Of course, since evolution is not progressive, then finding any so-called ‘anomalies’ that ‘deviate’ from the ‘progress’ in brain size evolution makes sense. They conclude that floresiensis’ brain size and body mass decrease fell within the expected range of Argue et al’s (2009) proposed phylogenetic scenario. Though, only if he evolved from habilis or Dmansi hominins if the insular dwarfism hypothesis was taken into account (which is a viable explanation for the decrease).

The effects of food scarcity and its effect on hominin brain size is hardly ever spoken about. However, as I’ve been documenting here recently, caloric quality and amount dictate brain size. Montgomeory et al (2010) write:

Although many studies have investigated the possible selective advantages and disadvantages of increased brain size in primates [5, 17, 18, 19, 20, 21], few consider how frequently brain size has reduced. Periods of primate evolution which show decreases in brain size are of great interest as they may yield insights into the selective pressures and developmental constraints acting on brain size. Bauchot & Stephan [22] noted the evolution of reduced brain size in the dwarf Old World monkey Miopithecus talapoin and Martin [23] suggested relative brain size in great apes may have undergone a reduction based on the cranial capacity of the extinct hominoid Proconsul africanus. Taylor & van Schaik [24]reported a reduced cranial capacity in Pongo pygmaeus morio compared to other Orang-utan populations and hypothesise this reduction is selected for as a result of scarcity of food. Finally, Henneberg [25] has shown that during the late Pleistocene human absolute brain size has decreased by 10%, accompanied by a parallel decrease in body size.

[…]

These authors suggest this reduction is associated with an increase in periods of food scarcity resulting in selection to minimise brain tissue which is metabolically expensive [17]. Food scarcity is also believed to have played a role in the decrease in brain size in the island bovid Myotragus [12]. Taylor & van Schaik [24] therefore propose that H. floresiensis may have experienced similar selective pressures as Myotragus and Pongo p. morio.

Nice empirical vindication for me, if I don’t say so myself. This lends further credence to my scenario of an asteroid impact on earth halting food production leading to a scarcity in food. It’s hypothesized that floresiensis went from eating (if evolved from erectus) 1800 kcal per day and 2500 while nursing to 1200 per day and 1400 while nursing (Lieberman, 2013: 125). This, again, is proof that big brains need adequate energy and that cooking meat was what specifically drove this facet of our evolution.

Montgomeroy et al (2010) conclude:

Finally, our analyses add to the growing number of studies that conclude that the evolution of the human brain size has not been anomalous when compared to general primate brain evolution [59, 61, 91, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94].

In other words, humans are not ‘special’ in terms of brain size. While there is a ‘trend’ in the increase in brain size, this ‘trend’ is only possible with the advent of fire, cooking, and meat eating. Without that causal mechanism, big brains would not be metabolically viable.

A big brain (large amounts of neurons) can only evolve with enough energy, mainly the advent of cooking meat (Herculano-Houzel, 2009). Primates have much higher neuronal densities than other mammals (Herculano-Houzel, Manger, and Kaas, 2014). Since the amount of energy the brain needs per day depends on how many total neurons it has (Azevedo and Herculano-Houzel, 2012), quality calories are needed to power such a metabolically expensive organ. Only with the advent of fire could we consume enough high-quality energy to evolve such big brains.

Mammalian brains that have 100 million neurons require .6 kcal, brains with 1 billion neurons use 6 kcal per day, and brains with 100 billion neurons use 600 kcal per day (humans with 86 billion neurons use 519 kcal, coming out to 6 kcal per neuron) regardless of the volumes of the brains (Herculano-Houzel, 2011). Knowing that the amount of neurons a brain has is directly related to how much energy it needs, it doesn’t seem so crazy now that, like with the example of floresiensis, a brain could decrease in size even when noticing this ‘upward trend’ in hominin brain size. This is simply because how big a brain is directly related to amount of energy available in an area as well as the most important variable: quality of the food.

If floresiensis is descended from habilis (and there is evidence that habilis was a meat eater, so along with a low amount of energy for floresiensis on Flora as well as there being no large predators on the island, a smaller size would have been advantageous to floresiensis), then this shows that what I’ve been saying for a few months is true: the diet quality as well as amount of energy dictates whether an organism evolves to be big or small. Energy is what ‘drives’ evolution in a sense and energy comes from kcal. The highest quality energy is from meat, and that fuels our ‘big brains’ with our high neuron count.

Imagine this scenario: an asteroid hits the earth and destroys the world power grid. All throughout the world, people cannot consume enough food. The sun is blocked by dust clouds for, say, 5000 years. The humans that survive this asteroid collision would evolve a smaller brain and body as well as better eyesight to see in an environment with low light, among other traits. Natural selection can only occur on the heritable variants already in the population, so whatever traits that would increase fitness in this scenario would multiply and flourish in the population, leading to a different, smaller-brained and smaller-bodied human due to the effects of the environment.

While on the subject of the decrease in human brain size, something that’s troubling to those who champion the ‘increase in hominin brain size’ as the ‘pinnacle of evolution’: our brains have been decreasing in size for at least the past 20,000 years according to John Hawks associate professor of anthropology at the University of Wisconsin-Madison. Keep in mind, this is someone that Pumpkin Person brings up saying that our brains have been increasing for the past 10,000 years. He has also said that the increase in better nutrition has allowed us to gain back the brain size of our hunter-gatherer ancestors (with no reference), which is not true. Because what John Hawks actually wrote on his blog about this says a different story:

The available skeletal samples show a reduction in endocranial volume or vault dimensions in Europe, southern Africa, China, and Australia during the Holocene. This reduction cannot be explained as an allometric consequence of reductions of body mass or stature in these populations. The large population numbers in these Holocene populations, particularly in post-agricultural Europe and China, rule out genetic drift as an explanation for smaller endocranial volume. This is likely to be true of African and Australian populations also, although the demographic information is less secure. Therefore, smaller endocranial volume was correlated with higher fitness during the recent evolution of these populations. Several hypotheses may explain the reduction of brain size in Holocene populations, and further work will be necessary to uncover the developmental and functional consequences of smaller brains.

Selection for smaller brains in Holocene human evolution

In fact, from the Discover article on decreasing brain size, John Hawks says:

Hawks spent last summer measuring skulls of Europeans dating from the Bronze Age, 4,000 years ago, to medieval times. Over that period the land became even more densely packed with people and, just as the Missouri team’s model predicts, the brain shrank more quickly than did overall body size, causing EQ values to fall. In short, Hawks documented the same trend as Geary and Bailey did in their older sample of fossils; in fact, the pattern he detected is even more pronounced. “Since the Bronze Age, the brain shrank a lot more than you would expect based on the decrease in body size,” Hawks reports. “For a brain as small as that found in the average European male today, the body would have to shrink to the size of a pygmy” to maintain proportional scaling.

This is in stark contrast to what PP claims he says about the evolution of human brain size over the past 10,000 years, especially Europeans who he claims Hawks has said there has been an increase in European brain size. An increase in brain size over the past 100 years doesn’t mean a trend is occurring upward, since all other data on human brain size says otherwise.

Our brains have begun to decrease in size, which is due to the effects of overnutrition and diseases of civilization brought on by processed foods and the agricultural revolution. Another proposed cause for this is that population density tracks with brain size, with brain size increasing with a smaller population and decreasing with a bigger population. In a way, this makes sense. A bigger brain should have more neurons than a smaller brain, which would aid in cognitive tasks and have that one hominin survive better giving it a better chance to pass on its genes, so if you think about it, when the population increases when social trust forms, you can piggyback off of others and they wouldn’t have to do things on their own. As population size increased from sparse to dense, brain size decreased with it.

On this notion of ‘progress’ in brain size, some people may assume that this puts us at the ‘pinnacle’ of evolution due to our superior cognitive ability (which is due to the remarkably large amount of neurons in our cerebral cortex [Hercualno-Houzel, 2016: 102]), Herculano-Houzel writes on page 91 of her book The Human Advantage: A New Understanding of How Our Brains Became Remarkable:

We have long deemed ourselves to be at the pinnacle of cognitive abilities among animals. But that is different than being at the pinnacle of evolution in a number of important ways. As Mark Twain pointed out in 1903, to presume that evolution has been a long path leading to humans as its crowning achievement is just as preposterous as presuming that the whole purpose of building the Eiffel Tower was to put the final coat of paint on its tip. Moreover, evolution is not synonmous with progress, but simply change over time. And humans aren’t even the youngest, most recently evolved species. For example, more than 500 new species of cichlid fish in Lake Victoria, the youngest of the great African Lakes, have appeared since it filled with water some 14,500 years ago.

Using PP’s logic, the cichlid fishes of Lake Victoria are ‘more highly evolved’ than we are since they’re a ‘newer species’. Using that line of logic makes no sense now, putting it in that way.

Looking at the ‘trend’ in human brain size over the past 7 million years, and its acceleration in the past 2 million, without thinking about what jumpstarted it (bipedalism, tools, fire, meat eating) is foolish. Moreover, any change to our environment that decreases our energy input would, over time, lead to a decrease in our overall brain size perhaps more rapidly, showing that this ‘trend’ in the increase in brain size is directly related to the quality and amount of food in the area. This is why floresiensis’ brain and body shrunk, and why certain primate lineages show increases in brain size: because they have a higher-quality diet. But it comes at a cost. Since primates largely eat a plant-based diet, they have to eat upwards of 10 hours a day to get enough energy to power either their brains or their bodies. If their bodies are large, their brains are small and vice versa. A plant-based diet cannot power a large brain with a high neuron count like we have, it’s only possible with meat eating (Azevedo and Herculano-Houzel, 2012). This is one reason why floresiensis’ brain shrunk along with not enough kcal to sustain their larger brain and body mass that their ancestor they evolved from previously had.

Our brains are not particularly special, and in a way, you can thank fire and cooking meat for everything that’s occurred since erectus first controlled fire. For without a quality diet in our evolution, this so-called ‘trend’ (which is based on the environment due to food quality and scarcity/abundance which fluctuate) would not have occurred. In sum, this ‘progress’ will halt and ‘reverse’ if the amount of energy consumed decreases or diet quality decreases.

Why Are Men Attracted To Low Waist-to-Hip Ratios?

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Why are men attracted to low waist-to-hip ratios (WHR)? Like with a lot of our preferences, there is an evolutionary reason why men are attracted to low WHR. I came across a paper the other day by M.D. William Lassek, “Assistant Professor of Epidemiology and Research Associate in the department of Anthropology at the University of California, Santa Barbara” and co-author P.h.D. Steven Gaulin, Professor of Anthropology with specific research interests in “evolutionary psychology, cognitive adaptations, the human voice, sexual selection, evolution of sex differences, lipid metabolism and brain evolution.” This paper fascinates me because it talks about the evolution of human intelligence through a lens of nutrition and micronutrients, something that I’m well-read on due to my career. First, I will discuss the benefits of fish oil and the main reason for taking them: omega-3 fatty acids and DHA. Then I will discuss the WHR/intelligence theory.

Fish Oils, DPA/EPA, and Omega-3 Fatty Acids

Misinformation about fish oils is rampant, specifically in the HBD-sphere, specifically with Steve Sailer’s article HBD and Diet AdviceThe study he cites (with no reference)  I assume is this study by Yano et al (1978) in which they found that Japanese men who ate more carbohydrates had less of a chance to die of cardiovascular heart disease (CHD). He says that the first generation ate mostly rice and no fat while the second generation “ate cheeseburgers and had higher rates of coronary disease than their parents.” He then says that these diet recommendations (low-fat, high-carb) were put onto all populations with no proven efficacy for all ethnies/racial groups. These diet recommendations began around two decades before the 80s, however.

He then quotes an article by the NYT science write, Carl Zimmer, talking about how the Inuit study has “added a new twist to the omega-3 fatty acid story”. Now, I read papers on nutrition every day due to my career, I don’t know what kind of literature they read on the subject, but fish oil, more specifically DPA/EPA and omega-3s are hugely important for optimal brain growth, health, and function.

Controlled studies clearly show that omega-3 consumption had a positive influence on n-3 (fatty acid) intake. N-3 has also been recognized as a modulator of inflammation as well as the fact that omega-3 fatty acids down-regulate genes involved in chronic inflammation, which show that n-3 is may be good for atherosclerosis.

An increase in omega-3 consumption leads to decreased damage from heart attacks.

Omega-3 may also reduce damage after a stroke.

Dietary epidemiology has also shown a link between n-3 and mental disorders such as Alzheimers and depression. N-3 intake is also linked to intelligence, vision and mood. Infants who don’t get enough n-3 prenatally are at risk for developing vision and nerve problems. Other studies have shown n-3’s effects on tumors, in particular, breast, colon and prostate cancer.

Omega-3’s are also great for muscle growth. Omega-3 intake in obese individuals along with exercise show a speed up in fat-loss for that individual.

Where do these people get their information from? Not only are omega-3’s good for damage reduction after a stroke and a heart attack, they’re also good for muscle growth, breast, colon and prostate tumor reduction, infants deficient in omega-3 prenatally are at risk for developing nerve and vision problems. Increase in omega-3 consumption is also linked to increases in cognition, reduces chronic inflammation and is linked to lower instances of depression.

Clearly, fish oils have a place in everyone’s diet, not only Inuits’.

This also reminds me of The Alternative Hypothesis’s argument that there are differing CHO metabolisms based on geographic origin (not true, to the best of my knowledge).

WHR and Intelligence

Most of the theories of the increase in brain size and intelligence have to do with climate, in one way or another, along with sexual selection. Though recently, I’ve been rethinking my position on cold winters having that big of an effect on intelligence due to some new information I’ve come across. The paper titled Waist-hip ratio and cognitive ability: is gluteofemoral fat a privileged store of neurodevelopmental resources? by Lassek and Gaudin (2008) posits a very sensible theory about the evolution of human intelligence: mainly that men prefer hour-glass figures due to an evolutionary adaptation.

Why may this be the case? One of the most important reasons I can think of is that women with high WHR have a higher chance of rate of death. The Nurses Health Study followed 44,000 women for 16 years and found that women who had waists bigger than 35 inches had a two times higher risk of dying from heart disease when compared to women with the lowest waist size of less than 28 inches. Clearly, men prefer women with low WHR since they will live longer, conceive more children and be around longer to take care of said children. So while a low WHR is not correlated with fertility per se, it is correlated with longevity, so the woman can have more children to spread more of her genes.

Lassek and Gaulin also bring up the ‘thrifty gene hypothesis’, which states that these genes evolved in populations that experienced nutritional stress, i.e., famines. I’ve read a lot of books on nutrition and human evolution (I highly recommend The Story of the Human Body: Evolution, Health, and Diseaseover the years and most of them discredit the idea of the thrifty gene hypothesis. However, recent research has shown the existence of these ‘thrifty genes’ in populations such as the Samoans and ‘Native’ Americans. It’s simple, really. Stop eating carbohydrates and the problems will fade away. (Hunter-gatherers don’t have these disease rates that we do in the West; it’s clear that the only difference is our diet and lifestyle. I will cover this in a future post titled “Diseases of Civilization”.)

Lassek and Gaulin pursued the hypothesis that gluteofemoral fat (fat stored in the thighs and buttocks) was the cause for the difference in the availability of neurodevelopmental nutrients available to a fetus. If correct, this could show why men prefer women with a low WHR and could show why we underwent such rapid brain growth: due to the availability of neurodevelopmental nutrients in the mother’s fat stores. Gluteofemoral body fat is the main source of long-chain polyunsaturated fatty acids (LPUFA) for children, along with another pertinent nutrient for fetal development: DHA. Lassek and Gaulin also state that 10 to 20 percent of the fat stored by a young woman during puberty is gluteofemoral fat, obviously priming her for childbearing. Even with caloric restriction, the gluteofemoral fat is not tapped utilized until late pregnancy/lactation when the baby needs nutrients such as DPA/EPA and omega-3s.

Further, 10 to 20 percent of the dry weight of the brain is made up of LCPUFA, which shows how important this one nutrient is for proper brain development in-vitro as well as the first few years of life. Lassek and Gaulin state:

A recent meta-analysis estimates that a child’s IQ increases by 0.13 point for every 100-mg increase in daily maternal prenatal intake of DHA (Cohen, Bellinger, Connor, & Shaywitz, 2005), and a recent study in England shows a similar positive relationship between a mother’s prenatal consumption of seafood (high in DHA) and her child’s verbal IQ (Hibbeln et al., 2007).

Along with what I cited above about these nutrients and their effects on our bodies while we’re in our adolescence and even adulthood, this is yet another huge reason WHY we should be consuming more fish oils, not only for the future intelligence of our offspring, but for our own brain health as a whole. Lassek and Gaulin state on pg. 3:

Each cycle of pregnancy and lactation draws down the gluteofemoral fat store deposited in early life; in many poorly nourished populations, this fat is not replaced, and women become progressively thinner with each pregnancy, which is termed “maternal depletion” (Lassek & Gaulin, 2006). We have recently shown that even well-nourished American women experience a relative loss of gluteofemoral fat with parity (Lassek & Gaulin, 2006). In parallel, parity is inversely related to the amount of DHA in the blood of mothers and neonates (Al, van Houwelingen, & Hornstra, 1997).

That critical fatty acids are depleted with parity is also consistent with studies showing that cognitive functioning is impaired with parity. IQ is negatively correlated with birth order (Downey, 2001), and twins have decreased DHA (McFadyen, Farquharson, & Cockburn, 2001) and compromised neurodevelopment compared to singletons (Ronalds, De Stavola, & Leon, 2005). The mother’s brain also typically decreases in size during pregnancy (Oatridge et al., 2002).

This also could explain why first born children are more intelligent than their siblings: because they have first dibs on the neurodevelopmental nutrients from the gluteofemoral fat, which aids in their brain growth and intelligence. What also lends credence to the theory is how the mother’s brain size typically decreases during pregnancy, due to the neurodevelopmental nutrients going to the child. (I also can’t help but wonder if this has any effect on Chinese IQ, since they had a nice increase in intelligence due to the Flynn Effect from 1982 to 2012. I will cover that in the future.)

“This hypothesis,” the authors write, “thus unites two derived (evolutionarily novel) features of Homo sapiens: sexually dimorphic fat distributions and large brains. On this view, a low WHR signals the availability of critical brain-building resources and should therefore have consequences for cognitive performance.”

The authors put forth three predictions for their study: 1) that a woman’s WHR should be negatively correlated with the cognitive ability of her offspring, 2) a woman’s WHR should be negatively correlated with her own intelligence since a woman passes on DPA as well as her own genes for low WHR to female offspring and 3) “cognitive development should be impaired in women whose first birth occurred early as well as in her future offspring, but lower WHRs, which indicate large stores of LCPUFA should be significantly protective for both” the mother and the child.

Lassek and Gaulin used data from the NHANES (National Health and Nutrition Examination Survey) III which included over 16,000 females with a mean age of 29.9 years. Measurements were taken on waist and hip circumference, WHR, BMI, and body fat as measured from bioelectrical impedance.*

For 752 “nulligravidas” (medical term for a woman who has never been pregnant), WHR explained 23 percent of the variance in total body fat estimated from the bioelectrical impedance (ugh, such a horrible measure). Moreover, “controlling for age and race/ethnicity” showed an increase of “0.01 in WHR increases total body fat by .83 kg” (1.82 pounds in freedom units). They also discovered that WHR explains 28 percent of the variance in BMI, with an increase of .47 kg per square meter, increasing the WHR by 0.01. BMI also explained 89 percent of the variance in body fat (garbage ‘body fat measuring instrument’ aside) with an increase of 1 kg per square meter increasing fat by 1.8 kg (close to 4 pounds in freedom units), but when added to the regression model, WHR made no additional contribution.

Lassek and Gaulin’s first hypothesis was corroborated when they found that the mother’s WHR was negatively correlated with the child’s intelligence on 4 cognitive tests. WHR accounted for 2.7 percent of the variation in test scores, “with a decrease of 0.01 in the mother’s current WHR increasing the child’s mean cognitive score by 0.061 points”. In the first subsample, they controlled for mother’s age, parental education, family income and race/ethnicity. Even when these variables were controlled for, WHR was still negatively correlated with the cognitive score. When these variables were controlled for, a decrease of 0.01 in WHR increased the average score by 0.024 points.

Their second hypothesis was also confirmed: that women with lower WHR would be more intelligent than women with higher WHRs. In girls aged 14-16, the WHR accounted for 3.6 percent of the variance in the average of the four cognitive tests. Also discovered was that in women aged 18 to 49, WHR accounted for 7 percent of the variance in years of education and 6 percent of the variance in two tests of cognitive ability. Even when controlling for age, parity, family income, age at first birth, and race/ethnicity, the negative correlation was still seen in 14 to 16-year-old girls.

There is also competition neurodevelopmental resources between mother and child. As I showed earlier in this article, a woman’s brain size decreases during pregnancy. This decrease in brain size during pregnancy is due to the babe getting more of the neurodevelopmental nutrients for brain growth from the mother. Clearly, as the mother’s stores of brain-growing nutrients become depleted, so does her brain size as te nutrients from her stored fat goes to developing the fetuses’ brain.

Lassek and Gaulin confirmed their hypothesis that a woman with a lower WHR would be more intelligent as well as have more intelligent children. WHR predicts the cognitive ability of the offspring while BMI does not. However, controlling for family income and parental education decreases the effect of WHR on the child’s intelligence, the effect still remains giving strong support to the hypothesis that women with low WHR pass on genes for low WHR as well as nutrients needed for neurodevelopment. Further, controlling for parental cognitive ability may mask the effects of the WHR. It’s well known that the mother’s intelligence is the best predictor for her offspring’s intelligence, which is due to the mother and grandmother passing on genes that augment the effect of LCPUFAs, along with the genes for lower WHR.

Women with a lower WHR were found to be more intelligent, and a lower WHR helps to protect cognitive resources (neurodevelopmental nutrients) for the mother and child. The mother’s body has a dilemma, though: it has to store nutrients for the mother’s own cognition; store resources for future pregnancies; and provide nutrients for their growing fetus. Obviously, especially in young mothers, this poses a problem as there is a conflict for what the brain should do with the nutrients the mother ingests. Children born to teenaged mothers have lower cognitive test scores, but, they are protected from this fate if the mother has a low WHR. This shows, definitively, that young mothers who are still growing will show no negative effects on their growth when pregnant if they have a low WHR which signals they have a large amount of LCPUFAs and other essential neurodevelopmental nutrients for the baby’s brain growth.

LCPUFAs are scarce in human diets. Thusly, an evolutionary preference for low WHR evolved for men so their children can have optimal nutrients while growing in the mother’s womb. The study confirmed that large brains, and along with it higher intelligence, and sexually dimorphic fat distribution have a strong link. Clearly, if a mother doesn’t have adequate levels of LCPUFAs, neurodevelopment will be impeded since the babe will not be getting the optimal nutrients for brain growth. Moreover, diets low in omega-3s should have consequences for intelligence and brain size of a baby, since when a baby is in the womb that is the most important time for it to get optimal brain nutrients. Is there any type of environment we can make ourselves and lifestyle choices we can take for ourselves, spouses and children to foster higher intelligence in them? I will cover that in the future.

Men love hour-glass figures, a low WHR. As I’ve shown in this article, there is an evolutionary reason for this. Men were asked to rate women who had surgery to move fat to their buttocks. Body weight stayed the same, but the fat was redistributed. It was found in brain scans of the men that the same parts of the brain related to reward lit up, including regions associated with drugs and alcohol. (more information here)

Conclusion

I’ve long known of the tons of positive benefits of omega-3 fatty acids and fish oil on human brain development. Fish oils and the nutrients in them are imperative for a healthy and growing brain. Without it, brain development will suffer. As a man, I can say firsthand that a low WHR is the most attractive. Now I understand the evolutionary reason behind it: fostering high intelligence due to the mothers lower-body fat stores. Omega-3s and LCPUFA are extremely important for optimal fetal brain growth. Moreover, the current American diet is low in omega-3s, while high in omega-6s. There is evidence of high omega-6 intake being related to obesity, metabolic syndromes, a progressive increase in body fat over the generationsThe omega-6 and -3 ratios in the body also play a role in obesity, with a lower omega-3 ratio and higher omega-6 ratio being related to obesity. This is due to adipogenesis, browning of the fat tissue, lipid homeostasis, and systemic inflammation. Clearly, as shown in this article, it’s imperative to have a balance of omega-3 and omega-6 fatty acids. This could also have to do with the hyperactivity of the cannabinoid system (which we all know what that’s involved with: eating more) and that could also be a cause for obesity with out-of-whack omega-6 to -3 fatty acid levels in the body. That’s for another day, though.

The totality of evidence is clear. If you want healthy children, choose a mate with a low WHR. She and her offspring will be more likely to be more intelligent. Clearly, if you’re reading this, you’re interested in intelligence as well as having the best possible life and life outcomes for your children. Well, choose a woman with a low WHR and you’ll be more likely to have more intelligent children!

* I have one problem with this study. They assessed body fat with bioelectrical impedance. The machine sends a light electrical current through the body and measures the degree of resistance to the flow of the current, which body fat can then be estimated. Problems with measuring body fat this way are as follows: it depends on how hydrated you are, whether you exercised that day, when you last ate, even whether your feet are calloused. Most importantly, they vary depending on the machine as well. Two differing machines will give two differing estimates. This is my only problem with the study. I would like if, in a follow-up study, they would use the DXA scan or hydrostatic weighing. These two techniques would be much better than using bioelectrical impedance, as the variables that prevent bioelectrical impedance from being a good way to measure body fat don’t exist with the DXA scan or hydrostatic weighing.

(Also see Eternal Curves by the Lassek and Gaulin and their book Why Women Need Fat for more information.)

Are Caesarian Sections Affecting Human Evolution?

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Our brains are the most metabolically demanding organ we have, sapping 5-600 kcal per day (25 percent of our daily energy needs). Due to how cost-efficient the brain is, it only would have evolved if it gave us a bigger fitness advantage (which it obviously did). In the news a couple of days ago, it broke that C-sections may be affecting our evolution. But in all of the articles I read about it I didn’t see any one of them talking about how C-sections may affect human evolution in America between race. Clearly, if  C-sections are having this effect on the country as a whole, there must be racial differences as well. Could this have an effect on brain size between race in America?

C-sections have increased in frequency since 1996. Clearly, if there is any selection it’s for more narrow-hipped women and bigger-brained babies. The regular use of C-sections has led to an evolutionary increase of fetopelvic disproportion rates by 10 to 20%. (Mitteroecker et al, 2016) Fetopelvic disproportion is the inability of a babe’s head to pass through the mother’s birth canal. This is because the head—and along with it the brain—is too big, leading to emergency C-sections. Mitteroecker et al (2016) also say (which slightly amused me):

Mitteroecker et al (2016) also say (which slightly amused me):

Neonatal size and maternal pelvic dimensions influence fitness (i.e., reproductive success) of the newborn and the mother in multiple ways. Undoubtedly, relative brain size had increased during human evolution in response to directional selection. Recently, it has also been suggested that the large human brain may be the result of runaway selection for the childcare of infants that are born prematurely because of their large brain (12). It is unclear whether any of this selection still persists after the slight decrease of brain size in the late Pleistocene. However, birth weight, which correlates with brain size at birth, is strongly positively associated with infant survival rate (13) and has also been reported to correlate negatively with the risk of multiple diseases (14). Reducing neonatal brain size by shortening gestation length seems to be equally disadvantageous: Delivery before term clearly increases the likelihood of impaired cognitive function in later life (15, 16).

Brain size is decreasing. Associate professor of anthropology at the University of Wisconsin John Hawks also states in his blog post, Selection for smaller brains in Holocene human evolution, where he says (contrary to Pumpkin Person’s assertion) that human brain size has gotten smaller in the past 10,000 years:

The available skeletal samples show a reduction in endocranial volume or vault dimensions in Europe, southern Africa, China, and Australia during the Holocene. This reduction cannot be explained as an allometric consequence of reductions of body mass or stature in these populations. The large population numbers in these Holocene populations, particularly in post-agricultural Europe and China, rule out genetic drift as an explanation for smaller endocranial volume. This is likely to be true of African and Australian populations also, although the demographic information is less secure. Therefore, smaller endocranial volume was correlated with higher fitness during the recent evolution of these populations. Several hypotheses may explain the reduction of brain size in Holocene populations, and further work will be necessary to uncover the developmental and functional consequences of smaller brains.

The reduction in brain size began around 28 kya and accelerated around 10 kya after the dawn of agriculture. The planet getting warmer also played a part in the decrease in brain size, which also allowed for the beginning of agriculture. Anyway, I’m sidetracking, I will return to this point in the future.

Large brains were also selected for since we needed to care for helpless babies. Natural selection for large brains led to more premature births which itself selected for even larger brains.

One-hundred years ago, a narrow-hipped mother who was pregnant with a big-headed baby would have died. Narrow-hipped women with big-headed babies can now survive, transmitting genes for both big brains and narrower pelvises. This is natural selection currently at work as we speak.

One thing that I obviously didn’t see in any article I’ve read on this matter is how will this affect racial differences in brain size? Which race has the most C-sections and will that select for bigger heads and smaller pelvises in that population?

Black women are substantially more likely to deliver by C-section than are white women (pg. 4). Though, one reason that C-sections occur is due to obesity. Black women are the most likely to be obese, which is part of the reason why they have more C-sections. If this trend continues, I could see a slight uptick in black brain size, as even smaller hips get selected for in black women, along with an increase in brain size. That’s one reason why Africans have smaller heads and brains than East Asians and Europeans: they have narrower hips which allows for better athleticism. Conversely, Europeans and East Asians have wider hips which allows for bigger-brained children but hampers athletic ability.

While on the topic of race and C-sections, Asian female-European Male couples have higher rates of C-sections. The obvious explanation is that the Asian woman’s pelvis is too narrow to birth bigger babies. In the study, Asian female-white male couples had babies that had a median weight of 8 pounds, while Asian-Asian couples had babies that had a median weight of 7.1 pounds and finally Asian male-white female couples’ babies had a median weight of 7.3 pounds. However, Asian female-white male couples had an increased rate of C-section deliveries, proving that a significant differences exist between sex of the parent (whether the father or mother is Asian or white influences birth weight) which leads to increased C-section rates due to the white father passing clearly influencing the birth weight more, thusly making it difficult for his Asian partner to birth the baby. There are 100 deaths per 100,000 live births per year in the U.S., a rate of .1 percent. Clearly, though the death rate is low, C-sections lead to maternal mortality and since Asian females are more likely to have a C-section when the father is white due to the baby being bigger, the mortality rate is slightly increased when this interracial pairing occurs.

C-sections are causing natural selection, favoring for bigger heads and narrower hips. This helped us, evolutionarily speaking, as human bipedalism is promoted by a narrow pelvis. C-sections could possibly select for bigger-brained African Americans. Though brain size has decreased in the past 10,000 years, our brain size will slightly increase over time due to this selection pressure. Asian women and white male couples have C-sections more often. Pretty good case against race-mixing, if I don’t say so myself.

More Thoughts on Bipedalism

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I wrote about bipedalism last week, however, in a conversation with a commented on PumpkinPerson’s blog, I came to a slightly different conclusion than I did in my previous article on the matter.

I quoted Daniel Liberman, author of the book The Story of the Human Body: Evolution, Health, and Disease:

As one might expect, other selective pressures are hypothesized to have favored bipedalism in the first hominins. Additional suggested advantages of being upright include improved abilities to make and use tools, to see over tall grass, to wade across streams, and even to swim. None of these hypotheses bear up under scrutiny. The oldest stone tools appear millions of years after bipedalism evolved.(Lieberman, 2013: 43)

However, after being linked to this journal article Shallow-water habitats as sources of fallback foods for homininsI began to rethink my position on this matter.

Now, the climate change when humans and chimps diverged is still the primary cause of bipedalism, but after reading this abstract, I came to think that the climate change (getting warmer) rose the sea levels which then drove Man to walk on two legs, gather food, and, eventually, wade in water to find more food which led to some selection for bipedalism in our ancestors. Humans needed to become bipedal to find more food as the climate change made their primary food more scarce. This then drove early Man into shallow waters to look for food.

As the climate was getting warmer, the same foodstuffs we ate were not as readily available. So what drove us to be bipedal was 1) the need for immediate food, i.e., looking for food on the forest floors and 2) when adequate food could not be found on the floors of the forests, Man then had to go into the water. This had multiple advantages. One could escape from predators, find more food with adequate nutrients which, in turn, had as evolve bigger brains, and the most important aspect, it’s much easier to be bipedal in water as it’s easier to stand in water.

This paper, The evolution of the upright posture and gait—a review and a new synthesisconcludes:

Wading was an appropriate trigger not only to stand up but also forced the primate to walk on. It seems likely that habitual bipedalism began not long after the separation from the gorilla and chimpanzee clade(s). From that time onwards, throwing could be evolved with free upper extremities much more successfully than before. Selective factors related to the reduction of incoming solar radiation became effective. Endurance running and adaptations to carry tools (like weapons) started their evolutionary improvements. If these processes took about 4 Ma, the wading hypothesis is consistent with a rather perfect bipedal anatomy as shown, e.g., in Homo ergaster (WT 15000), about 1.6 Ma ago. In this way, many of the hypotheses competing in the past may be harmonised, as some of them have yielded important contributions to the understanding of the evolution of the human habitual upright gait.

The first sentence corroborates what Lieberman says in The Story of the Human Body. The final sentence brings together all of the theories that drove bipedalism in humans into a ‘new synthesis’.

Now, climate change (the earth getting warmer) is still the ultimate cause, but a proximate cause of bipedalism is wading in the water to 1) find more food and 2) escape predators.

This ‘new synthesis’ of how Man became bipedal is a great way to unify a lot of theories of bipedalism that gave us great understanding of human evolution in regards to bipedalism. In that vain, it’s like E.O. Wilson’s Sociobiology: A New Synthesis in which he sought to unify the evolutionary mechanics of altruism, aggression, and nurturance– our main social behaviors. This ‘new synthesis’ in the study of how we became bipedal unifies competing theories into a more understandable theory.

Moreover, bipedalism made it easier to consume more kcal which led to bigger brains. To quote Suzana Herculano-Houzel from her book The Human Advantage: A New Understanding of How Our Brain Became Remarkable:

“The remaining way to work around an energetic constraint to the number of neurons in the brain involves dietary changes that would allow for more calories to be obtained in the same amount of time, or even less. Some first changes in that direction probably took place 4 million years ago when our australopithecine ancestors stood upright and became habitual bipeds. As Daniel Lieberman explores in detail in The Story of the Human Body, bipedality potentially increases the amount of calories that can be amassed in a day by extending the range of food picking, for it is much easier and costs four times fewer kilocalories to walk on two feet, as humans do, than on all fours, as modern great apes do and the ancestor from which australopithecines originated must have done. Roaming away from home to find food, is the definition of a food gatherer, as opposed to a food picker, which is what great apes remain to this day. Bipedality made food gatherers of our ancestors.” (Herculano-Houzel, 2016: 189)

bipedalism-and-cooking

This graph from her book shows that bipedality preceded cooking which increased our brain size (I will write on that soon).

More neurons in the cerebral cortex is the cause for our amazing brains. But we are NOT unique!! This kcal increase led to more neurons in our cerebral cortex which then allowed for reasoning, finding patterns, developing technology and passing it on through culture. Cooking is why we are so ‘unique’ in comparison to other animals. As shown in the graph above, the increase in brain size happened around the time of H. Erectus. They show smaller teeth at that period, which shows that the selection was already occurring. The smaller teeth to break down food more to extract nutrients from the food they gathered shows that bipedalism evolved alongside the evolution of smaller teeth.

In sum, the ultimate cause of bipedality is still climate change, but the proximate cause, in part, was wading in the water which led to our ancestors to find more food. And, over time, we were selected for bipedalism as I wrote in my previous article on the matter. We can see that bipedalism slightly predated cooking, which the ultimate cause of which was to find more food. This is seen in the records we have. I will write more on this in the future as I read into this more.

Neanderthals, Inbreeding, r/K Selection Theory and Eurasian Birthrates

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Science Daily reported last week that Neanderthals left humans a genetic burden, which is having less offspring. Of course, these deleterious alleles only introgressed into non-African populations due to Africans not leaving Africa. This manifests itself today in birth rates within countries and between them based on the ethnic/racial mix. And (not) coincidentally, the areas with the highest rate of children are in sub-Saharan Africa.

The Neanderthals existed in small bands, so inbreeding was common. Due to this inbreeding, Neanderthals were more homogenous than we are today. When humans migrated out of Africa, they encountered the inbred Neanderthals who they interbred with. Harmful genetic variants acquired from Neanderthals are shown to reduce the fitness of populations with certain deleterious alleles. There are of course tradeoffs with everything in life. Increased intelligence and being better able to weather the Ice Age, among numerous other factors, were positive things gained from interbreeding with  Neanderthals. Negative effects were the acquisition of deleterious alleles which still persist today in non-African hominids. These deleterious alleles decreased biological fitness which manifests itself in the birthrate of Eurasian populations throughout the world (the Germann and Japanese birthrate is 1.3 for reference).

Harris and Nielson also hypothesize that since Neanderthals existed in small bands that natural selection was less effective, allowing for weakly harmful mutations to pass on and not get weeded out over the generations. However, when introduced back into humans these effects become lost over time due to a large population with natural selection selecting against the deleterious Neanderthal alleles. Using a computer program, Harris and Nielson quantify how much of a negative effect the Neanderthal genome had on modern populations. The conclusion of the results was that Neanderthals are 40 percent LESS genetically fit than modern humans.

The researchers’ simulations also suggest that humans and Neanderthals mated more freely, which leads more credence to the idea that Neanderthals got absorbed into the Homo Sapien population and not mostly killed off. The estimation for Neanderthal DNA in modern hominids from the simulation was around 10 percent, which then continued to drop as the Neanderthal-Homo Sapiens hybrids interbred with those who hardly had any Neanderthal DNA. More evidence also shows that the percentage of Neanderthal DNA was higher in the past in Eurasians as well. Which makes sense since Asians have on average 20 percent more Neanderthal DNA than Europeans due to a second interbreeding event.

However, Harris and Nielson end up concluding that non-Africans historically had a 1 percent loss in biological fitness due to Neanderthal genetics. Moreover, a better immune system came from Neanderthal genetics. Skin color is another trait inherited from Neanderthals as well.

Along with the acquisition of deleterious Neanderthal alleles, early Eurasians also encountered the same environment as the Neanderthals. Those selection pressures, along with interbreeding due to small bands lead to a decrease in the number of children had. Fewer children are easier to care for as well as show more attention to. All of these variables in that environment lead to fewer children produced. It’s a better evolutionary strategy to have fewer children in more northerly climes than in more southerly ones due to the differing selection pressures. Environmental effects are also one reason why birthrates are lower for populations that evolved in northerly climes (Neanderthals and post-OoA hominids). Harsh winters lead to a decreased population size, as evidenced by the Inuit and Eskimoes, which their low population size didn’t allow for selection for high IQ despite having the same brain size as East Asians.

I couldn’t help but think that, yet again, for the second time in two weeks, one of JP Rushton’s theories was confirmed. This confirms one of the many variables of Rushton’s r/K Selection Theory. Just like I covered how Piantadosi and Kidd corroborated Rushton’s theory of brain size and earlier child birth. Neanderthals had bigger brains than we do today, and knowing what we know about the correlation between IQ, brain size and early childbirth, I would assume that Neanderthals also had earlier childbirths as well,.

Along with these deleterious gene variants from Neanderthals, other variables that contribute to the decline in Eurasian populations also include higher IQ as well, as JP Rushton says, is an extreme way to have control over their environment and individuality. These traits are seen in higher IQ populations in comparison to lower IQ populations. We could also make the inference that since Eurasian children have bigger heads, that multiple childbirths would be taxing on the Eurasian woman’s birth canal while it would be less taxing on the African woman’s.

This study also shows that Neanderthals also had less offspring due to being more intelligent. They had bigger brains than we do today, and since we know that higher IQ is correlated with fewer children conceived, we can say that they were pretty damn smart (they buried their dead 50,000 years ago. There was also a recent discovery of a 176,500-year-old Neanderthal constructions in a French cave).  A main cause for the current trend in birthrates in Eurasian populations is due interbreeding with Neanderthals. These events also attributed more to the decline of the Neanderthals.

Deleterious Neanderthal alleles are yet another reason for lower Eurasian birthrates, which shows = that the current trend currently happening in the world with these populations is natural and evolutionarily based. I’ve said a few times that by showing positive things to women on television will increase the white birth rate, with Rushton cites National Socialist Germany as one example. By showing women happy with children, this lead to a massive boom in the German population. To ameliorate the effects of low natural birth rates, these positive things need to be shown on television to women to start to reverse the effects of low natural childbirths.

It’s been a great month for Rushton’s theories, with two of them being corroborated in one month. It’s only a matter of time before the denial of human nature is completely discarded from modern science. As the data piles up on human genetic diversity we will not be able to deny these clearly evident factors any longer.

Chinese IQ

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The Chinese have one of the highest IQs in the world. Their 100 and 108 in Hong Kong give them an average of 104. Chinese intelligence has been increasing from the 1940s all the way to today. This is the ‘Flynn Effect’ in action. Lui and Lynn (2013) reported that IQ scores are improving for 12-year-old Chinese children. The increases are as follows: 6.19 points for full-scale IQ,  6.55 points for performance IQ, and 1.91 points for verbal IQ. The Jintan Child Study is an ongoing longitudinal study to show the effects of health and cognitive ability.

They used 1656 6th graders (55.5 percent boys and 45.5 percent girls, “consisting of 24.3% of all children in this age range in the Jintan city region born in 1999.”) who either graduated or currently were in the grade with an average age of 12.2 years. The study from 86-87 used only individuals from urban areas, so Liu and Lynn did the same. They conclude that over the 26 years from the original study, between the two data sets that increases of 2.38 points on full-scale IQ, .73 points on verbal, and 2.52 points on performance IQ per decade. They theorize that economic development is a cause of rising IQ scores due to better nutrition. The study concludes a 105.89 IQ for the 12-year-olds in the study.

Liu and Lynn (2015) also observed the same sex differences in the same magnitude in Chinese and American boys and girls. In a study of 788 children aged 12 years old, boys obtained a higher IQ by 3.75 points on average. This exactly mirrors what Rushton and Jackson (2005) say about American men and women who are college aged. They state that males score 3.63 points higher than women. Liu and Lynn state that boys obtained 4.20 points higher in performance IQ, and 2.40 points higher in verbal IQ. This is what we would expect, evolutionarily speaking. The men need to be more intelligent to provide food, whereas women need to have a higher verbal IQ to be able to talk to and take care of children. The fact that the magnitude of sex differences in IQ between men and women has been noticed in the U.S. and China shows that sex differences in the brain do exist.

Better nutrition is a definite cause for the rise in IQ for the Chinese. Richard Lynn says that better nutrition is critical for increased cognitive functioning. This is one reason why Africa’s IQ is so low. Due to more Chinese getting better jobs and making more money, they were getting higher quality foods in order to be adequately nourished. Better nutrition explains most, if not all of the Flynn Effect. It’s what to expect if this phenomenon was not on (it’s not), it’s on the intelligence that is affected by the environment, hence, bigger increases on that type of intelligence in comparison to the intelligence highly correlated with g.

The Chinese have the largest cranial capacity at 1492 ml. The bigger one’s brain, the more cortical neurons it has which allows for better cognitive processing. Piantadosi and Kidd (2016) corroborated one of Rushton’s theories on brain size and child rearing. Mainly that r/K selection theory explains Piantadosi and Kidd’s theory of earlier births being correlated with higher intelligence due to greater necessity to care for the more vulnerable child in comparison to those with smaller brains. Moreover, since East Asians have more myelin in the brain, this too adds to their higher cognition. Since the correlation between brain size and IQ is .35, a good amount of the variance in IQ can be explained by brain size.

We can also look at Chinese outside of China. Singapore, for instance, has an IQ of 108, the highest in the world. They’re also 74.4 percent Chinese. This is then mirrored in their IQ as well as their economy. Anywhere the Chinese go they are high achievers in both IQ as well as wealth attainment.

There are other measures to show that Chinese have higher IQs. In tests of reaction times, Rushton and Jensen (2005) say that East Asians beat whites while whites beat blacks. Since faster reaction times are associated with a more efficient brain, East Asians have a higher IQ as a result of that. Though, they are weak on verbal IQ, average 99 for Chinese in America and China, they are superior in visio-spatial IQ. This is due to their ancestors evolving in the harsh winters of Siberia which lead to being more K-selected and selecting for bigger brains which lead to children being born earlier and higher intelligence evolving to better care for defenseless children. Bigger brains also evolved due to colder temperatures, which is another cause for earlier childbirth and an even bigger increase in general intelligence to adapt.

IQ in China is higher in urban areas than in rural areas, which is seen in America as well. This is due to those with higher intelligence having the ability to be able to live in the city due to a better ability to attain wealth due to higher IQ. Those in rural areas have lower IQ, some having a lower IQ genetically, while others are depressed by bad nutrition. So with better nutrition, a lot of the rural Chinese would get an IQ boost. Nutrition is critical for brain development in vitro as well as in early childhood leading into young adulthood. This ensures the brain has adequate nutrients for growth and in turn grows to its full potential.

The Chinese are the best example of Rushton’s theory of intelligence and brain size. No matter where they go, if they have adequate nutrition, they have the biggest brains and highest IQs which shows in scholastic achievement as well as wealth attainment. The increase in full-scale IQ for China in the past 30 years is due to better nutrition as well as economic growth. Singapore has one of the world’s best economies and is 74.4 percent Chinese.

This extreme K-selection, though, is causing the Chinese birth rate to drop. This is the curse for high IQ peoples. They have a lower birth rate in comparison to those with lower IQs who have a higher birth rate. The current birth rate in China is 1.66. That is devastatingly low, almost as low as Germany and Japan (both at 1.3) and they have similar IQs as well. It seems that this intelligence increase is coming with a lower birth rate. Higher intelligence is correlated with a lower sex drive so this is another cause for the lower birth rate in East Asian countries as these slight IQ increases continue to occur. The same sex differences as seen in America were also seen in China, giving more evidence to the sexual selection theory of intelligence.