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Otzi Man’s Last Meal and the Diet of Neanderthals
1100 words
The debate on what type of diet in regard to macronutrient differences rages on. Should we eat high carb, low fat (HCLF)? Or low carb, high fat (LCHF) or something in between? The answer rests on, of course, the type of diets that our ancestors ate—both immediate and in the distant past. In the 1990s, a frozen human was discovered in the Otzal mountains, which gave him the name “Otzi man.” About 5,300 years ago, he was frozen in the mountains. The contents of his stomach have been analyzed in the 27 years since the discovery of Otzi, but an in-depth analysis was not possible until now.
A new paper was published recently, which analyzed the stomach contents of Otzi man (Maixner et al, 2018). There is one reason why it took so long to analyze the contents of his stomach: the authors state that, due to mummification, his stomach moved high up into his rib cage. The Iceman was “omnivorous, with a diet consisting both of wild animal and plant material” (Maixner et al, 2018: 2). They found that his stomach had a really high fat content, with “the presence of ibex and red deer” (pg 3). He also “consumed either fresh or dried wild meat“, while “a slow drying or smoking of the meat over the fire would explain the charcoal particles detected previously in the lower intestine content.“(pg 5).
The extreme alpine environment in which the Iceman lived and where he have been found (3,210 m above sea level) is particularly challenging for the human physiology and requires optimal nutrient supply to avoid rapid starvation and energy loss [31]. Therefore, the Iceman seemed to have been fully aware that fat displays an excellent energy source. On the other hand, the intake of animal adipose tissue fat has a strong correlation with increased risk of coronary artery disease [32]. A high saturated fats diet raises cholesterol levels in the blood, which in turn can lead to atherosclerosis. Importantly, computed tomography scans of the Iceman showed major calcifications in arteria and the aorta indicating an already advanced atherosclerotic disease state [33]. Both his high-fat diet and his genetic predisposition for cardiovascular disease [34] could have significantly contributed to the development of the arterial calcifications. Finally, we could show that the Iceman either consumed fresh or dried meat. Drying meat by smoking or in the open air are simple but highly effective methods for meat preservation that would have allowed the Iceman to store meat long term on journeys or in periods of food scarcity. In summary, the Iceman’s last meal was a well-balanced mix of carbohydrates, proteins, and lipids, perfectly adjusted to the energetic requirements of his high-altitude trekking. (Maixner et al, 2018: 5)
They claim that “the intake of animal adipose tissue fat has a strong correlation with increased risk of coronary artery disease“, of course, citing a paper that the AHA is involved in (Sacks et al, 2017) which says that “Randomized clinical trials showed that polyunsaturated fat from vegetable oils replacing saturated fats from dairy and meat lowers CVD.” This is nonsense, because dietary fat guidelines have no evidence (Harcombe et al, 2016; Harcombe, Baker, and Davies, 2016; Harcombe, 2017). Saturated fat consumption is not even associated with all-cause mortality, type II diabetes, ischemic stroke, CVD (cardiovascular disease) and CHD (coronary heart disease) (de Sousa et al, 2015).
Thus, if anything, what contributed to Otzi man’s arterial calcification seems to be grains/carbohydrates (see DiNicolantonio et al, 2017), not animal fat. Fats, at 9 kcal per gram, were better for Otzi to consume, as he got more kcal for his buck; eating a similar portion in carbohydrates, for example, would have meant that Otzi would have had to spend more time eating (since carbs have less than half the energy that animal fat does). Since his stomach had ibex (a type of goat) and red deer, it’s safe to say that many of his meals consisted mainly of animal fat, protein with some cereals and plants thrown in (he was an omnivore).
We can then contrast the findings of Otzi’s diet with that of Neanderthals. It has been estimated that, during glacial winters, Neanderthals would have consumed around 74-85 percent of their diet from animal fat when there were no carbohydrates around, with the rest coming from protein (Ben-Dor, Gopher, and Barkai, 2016). Furthermore, based on contemporary data from polar peoples, it is estimated that Neanderthals required around 3,360 to 4,480 kcal per day to winter foraging and cold resistance (Steegmann, Cerny, and Holliday, 2002). The upper-limit for protein intake for Homo sapiens is 4.0 g/bw/day while for erectus it is 3.9 g/bw/day (Ben-Dor et al, 2011), and so this shows that Neanderthals consumed a theoretical upper-maximum of protein due to their large body size. So we can assume that Neanderthals consumed somewhere near 3800 kcal per day. The average Neanderthal is said to have consumed about 292 grams of protein per day, or 1,170 kcal (with a lower end of 985 kcal and an upper end of 1,170 at the high end) (Ben-Dor, Gopher, and Barkai, 2016: 370).
Then if we further assume that Neanderthals consumed no carbohydrates during glacial winters, that leaves protein as the main source of energy, since the large game the Neanderthals hunted were not around. Thus, Neanderthals would have consumed between 2,812 and 3,230 kcal from animal fat with the rest coming from protein. We can also put this into perspective. The average American man consumes about 100 grams of protein per day, while consuming 2,195 kcal per day (Ford and Dietz, 2013). For these reasons, and more, I argued that Neanderthals were significantly stronger than Homo sapiens, and this does have implications for racial differences in athletic ability.
In sum, the last meal of Otzi man is now known. Of course, this is a case of n = 1, so we should not draw too large a conclusion from this, but it is interesting. I don’t see why the composition of the diets of any of Otzi’s relatives would have been any different (or that the contents of his normal diet would have been any different). He ate a diet high in animal fat like Neanderthals, but unlike Neanderthals, they ate a more cereal-based diet which may have contributed to Otzi’s CVD and arterial calcification. We can learn a lot about ourselves and our ancestors through the analysis of their stomach contents (if possible) and teeth (if possible), and maybe even genomes (Berens, Cooper, and Lachance, 2017) because if we learn what they ate then we can maybe begin to shift dietary advice to a more ‘natural’ way and avoid diseases of civilization. But, we have not had time to adapt to the new obesogenic environments we have constructed for ourselves. It’s due to this that we have an obesity epidemic, and by studying the diets of our ancestors, we can then begin to remedy our obesity and other health problems.
Cold Winter Theory, the Vitamin D Hypothesis and the Prediction of Novel Facts
2400 words
HBDers purport that as one moves further north from Africa that IQ raises as a function of how the population in question needed to survive. The explanation is that as our species migrated out of Africa, more “intelligence” was needed and this is what explains the current IQ disparities across the world: the ancestors of populations evolving in different areas with different demands then changed their “IQs” and this then is responsible for differential national development between nations. Cold winter theory (CWT) explains these disparities.
On the other hand is the vitamin D hypothesis (VDH). The VDH purports to explain why populations have light skin at northern latitudes. As the migration north out of Africa occurred, peoples needed to get progressively lighter in order to synthesize vitamin D. The observation here is that as light skin is selected for in locations where UVB is absent, seasonal or more variable whereas dark skin is selected for where UVB is stronger. So we have two hypotheses: but there is a problem. Only one of these hypotheses makes novel predictions. Predictions of novel predictions are what science truly is. A predicted fact is a novel fact for a hypothesis if it wasn’t used in the construction of the hypothesis (Musgrave, 1988). In this article, I will cover both the CWT and VDH, predictions of facts that each made (or didn’t make) and which can be called “science”.
Cold winter theory
The cold winter theory, formulated by Lynn and Rushton, purports to give an evolutionary explanation for differences in national IQs: certain populations evolved in areas with deathly cold winters in the north, while those who lived in tropical climes had, in comparison to those who evolved in the north, an “easier time to live”. Over time as populations adapted to their environments, differences in ‘intelligence’ (whatever that is) evolved due to the different demands of each environment, or so the HBDers say.
Put simply, the CWT states that IQ differences exist due to different evolutionary pressures. Since our species migrated into cold, novel environments, this was the selective pressure needed for higher levels of ‘intelligence’. On the other hand, humans who remained in Africa and other tropical locations did experience these novel, cold environments and so their ‘intelligence’ stayed at around the same level as it was 70,000 years ago. Many authors hold this theory, including Rushton (1997), Lynn (2006), Hart, (2007) Kanazawa (2008), Rushton and Templer (2012; see my thoughts on their hypothesis here) and Wade (2014). Lynn (2013) even spoke of a “widespreadonsensus” on the CWT, writing:
“There is widespread consensus on this thesis, e.g. Kanazawa (2008), Lynn (1991, 2006), and Templer and Arikawa (2006).”
So this “consensus” seems to be a group of his friends and his own publications. We can change this sentence to ““There is widespread consensus on this thesis, including two of my publications, a paper where the author assumes that the earth is flat: “First, Kanazawa’s (2008) computations of geographic distance used Pythagoras’ theorem and so the paper assumed that the earth is flat (Gelade, 2008).” (Wicherts et al, 2012) and another publication where the authors assume hot weather leads to lower intelligence. Oh yea, they’re all PF members. Weird.” That Lynn (2013) calls this “consensus” is a joke.
What caused higher levels of ‘intelligence’ in those that migrated out of Africa? Well, according to those who push the CWT, finding food and shelter. Kanazawa, Lynn, and Rushton all argue that finding food, making shelter and hunting animals were all harder in Eurasia than in Africa.
One explanation for high IQs of people who evolved recently in northern climes is their brain size. Lynn (2006: 139) cites data showing the average brain sizes of populations, along with the temperatures in that location:
Do note the anomaly with the Arctic peoples. To explain this away in an ad-hoc manner, Lynn (2006: 156-7) writes:
These severe winters would be expected to have acted as a strong selection for increased intelligence, but this evidently failed to occur because their IQ is only 91. The explanation for this must lie in the small numbers of the Arctic Peoples whose population at the end of the twentieth century was only approximately 56,000 as compared with approximately 1.4 billion East Asians.
This is completely ad-hoc. There is no independent verifier for the claim. That the Arcitic don’t have the highest IQs but experienced the harshest temperatures and therefore have the biggest brain size is a huge anomaly, which Lynn (2006) attempts to explain away by population size.
He does not explain why natural selection among Arctic peoples would result in larger brain sizes or enhanced visual memory yet the same evolutionary pressures associated with a cold environment would not also produce higher intelligence. Arctic peoples have clear physical adaptations to the cold, such as short, stocky bodies well-suited to conserving heat.
Furthermore, the argument that Lynn attempts is on the mutations/population size is special pleading—he is ignoring anomalies in his theory that don’t fit it. However, “evolution is not necessary for temperature and IQ to co-vary across geographic space” (Pesta and Poznanski, 2014).
If high ‘intelligence’ is supposedly an adaptation to cold temperatures, then what is the observation that disconfirms a byproduct hypothesis? On the other hand, if ‘intelligence’ is a byproduct, which observation would disconfirm an adaptationist hypothesis? No possible observation can confirm or disconfirm either hypothesis, therefore they are just-so stories. Since a byproduct explanation would explain the same phenomena since byproducts are also inherited, then just saying that ‘intelligence’ is a byproduct of, say, needing larger heads to dissipate heat (Lieberman, 2015). One can make any story they want to fit the data, but if there is no prediction of novel facts then how useful is the hypothesis if it explains the data it purports to explain and only the data it purports to explain?
It is indeed possible to argue that hotter climates need higher levels of intelligence than colder climates, which has been argued in the past (see Anderson, 1991; Graves, 2002; Sternberg, Grigorenko, and Kidd, 2005). Indeed, Sternberg, Grigorenko, and Kidd (2005: 50) write: “post hoc evolutionary arguments … can have the character of ad hoc “just so” stories designed to support, in retrospect, whatever point the author wishes to make about present-day people.” One can think up any “just-so” story to explain any data. But if the “just-so” story doesn’t make any risky predictions of novel facts, then it’s not science, but pseudoscience.
Vitamin D hypothesis
The VDH is simple: those populations that evolved in areas with seasonal, absent, or more variable levels of UVB have lighter skin than populations that evolved in areas with strong UVB levels year-round (Chaplan and Jablonksi, 2009: 458). Robins (2009) is a huge critic of the VDH, though her objections to the VDH have been answered (and will be discussed below).
The VDH is similar to the CWT in that it postulates that the adaptations in question only arose due to migrations out of our ancestral lands. We can see a very strong relationship between high UVB rays and dark skin and conversely with low UVB rays and light skin. Like with the CWT, the VDH has an anomaly and, coincidentally, the anomaly has to do with the same population involved in the CWT anomaly.
Arctic people have dark-ish skin for living in the climate that they do. But since they live in very cold climates then we have a strange anomaly here that needs explaining. We only need to look at the environment around them. They are surrounded by ice. Ice reflects UVB rays. UVB rays hit the skin. Arctic people consume a diet high in vitamin D (from fish). Therefore what explains Arctic skin color is UVB rays bouncing off the ice along with their high vitamin D diet. The sun’s rays are, actually, more dangerous in the snow than on the beach, with UVB rays being 2.5 more times dangerous in the snow than beach.
Evolution in different geographic locations over tens of thousands of years caused skin color differences. Thus, we can expect that, if peoples are out of the conditions where their ancestors evolved their skin color, that there would then be expected complications. For example, if human skin pigmentation is an adaptation to UV rays (Jablonski and Chaplan, 2010), we should expect that, when populations are removed from their ancestral lands and are in new locations with differing levels of UV rays, that there would be a subsequent uptick in diseases caused by vitamin D deficiencies.
This is what we find. We find significant differences in circulating serum vitamin D levels, and these circulating serum vitamin D levels then predict health outcomes in certain populations. This would only be true if sunlight influenced vitamin D production and that skin progressively gets lighter as one moves away from Africa and other tropical locations.
Skin pigmentation regulates vitamin D production (Neer, 1975). This is due to the fact that when UVB rays strike the skin, we synthesize vitamin D, and the lighter one’s skin is, the more vitamin D can be synthesized in areas with fewer UVB rays. (Also see Daraghmeh et al, 2016 for more evidence for the vitamin D hypothesis.)
P1) UV rays generate vitamin D in human skin
P2) Human populations that migrate to climates with less sunlight get fewer UV rays
P3) To produce more vitamin D, the skin needs to get progressively lighter
C) Therefore, what explains human skin variation is climate and UV rays linked to vitamin D production in the skin.
Novel predictions
Science is the generation of novel facts from risky predictions (Musgrave, 1988; Winther, 2009). And so, hypotheses that predict novel facts from risky predictions are scientific hypotheses, whereas those hypotheses that need to continuously backtrack and think up ad-hoc hypotheses are then pseudoscientific. Pseudoscience is simple enough to define. The Stanford Encyclopedia of Philosophy defines it as:
“A pretended or spurious science; a collection of related beliefs about the world mistakenly regarded as being based on scientific method or as having the status that scientific truths now have.”
All theories have a protective belt of ad hoc hypotheses. Theories become pseudoscientific when they fail to make new predictions and must take on more and more ad-hoc hypotheses that have no predictive value. If the ad-hoc hypotheses that are added to the main hypothesis have no predictive value then the new explanations for whichever hypothesis that is in danger of being falsified are just used to save the hypothesis from being refuted and it thus becomes pseudoscience.
In the case of CWT, it makes no prediction of novel facts; it only explains the data that it purports to explain. What is so great about the CWT if it makes no predictions of novel facts and only explains what it purports to explain? One may attempt to argue that it has made some ‘novel’ predictions but the ‘predictions’ that are proposed are not risky at all.
For example, Hart (2007: 417) makes a few “predictions”, but whether or not they’re “risky” or “novel” I’ll let you decide (I think they’re neither, of course). He writes that very few accomplishments will be made by Africans, or Australian or New Guinean Aborigines; members of those groups will not be highly represented in chess; and that major advances in scientific fields will come from those of European ancestry or the “Monglids”, Koreans, Chinese or Japanese.
On the other hand, Hart (2007: 417) makes two more “predictions”: he says that IQ data for Congoid Pygmies, Andaman Islanders, and Bantu-speaking people are few and far between and he believes that when enough IQ testing is undertaken there he expects IQ values between 60 and 85. Conversely, for the Lapps, Siberians, Eskimoes, Mongols and Tibetans, he predicts that IQ values should be between 85-105. He then states that if these “predictions” turn out to be wrong then he would have to admit that his hypothesis is wrong. But the thing is, he chose “predictions” that he knew would come to pass and therefore these are not novel, risky predictions but are predictions that Hart (2007) knows would come to pass.
What novel predictions has the VDH made? This is very simple. The convergent evolution of light skin was predicted in all hominids that trekked out of Africa and into colder lands. This occurred “because of the importance of maintaining the potential for producing pre-vitamin D3 in the skin under conditions of low annual UVB (Jablonski and Chaplin, 2000; Jablonski, 2004)” while these predictions “have been borne out by recent genetic studies, which have demonstrated that depigmented skin evolved independently by different molecular mechanisms multiple times in the history of the human lineage” (Chaplan and Jablonksi, 2009: 452). This was successfully predicted by Chaplan and Jablonski (2000).
The VDH still holds explanatory scope and predictive success; no other agent other than vitamin D can explain the observation that light skin is selected for in areas where there is low, absent or seasonal UVB. Conversely, in areas where there is a strong, year-round presence of UVB rays, dark skin is selected for.
Conclusion
Scientific hypotheses predict novel facts not known before the formulation of the hypothesis. The VDT has successfully predicted novel facts, whereas I am at a loss thinking of a novel fact that the CWT predicted.
In order to push an adaptationist hypothesis for CWT and ‘intelligence’, one must propose an observation that would confirm the adaptationist hypothesis while at the same time disconfirming the byproduct hypothesis. Since byproducts are inherited to, the byproduct hypothesis would predict the same things that an adaptationist hypothesis would. Thus, the CWT is a just-so story since no observation would confirm or disconfirm either hypothesis. On the other hand, the CWT doesn’t make predictions of novel facts, it makes “predictions” that are already known and would not undermine the hypothesis if disproved (but there would always be a proponent of the CWT waiting in the wings to propose an ad-hoc hypothesis in order to save the CWT, but I have already established that it isn’t science).
On the other hand, the VDT has successfully predicted that hominins that trekked out of Africa would have light skin which was then subsequently confirmed by genomic evidence. The fact that strong UVB rays year-round predict dark skin whereas seasonal, absent, or low levels of UVB predict light skin has been proved to be true. With the advent of genomic testing, it has been shown that hominids that migrated out of Africa did indeed have lighter skin. This is independent verification for the VDH; the VDH has predicted a novel fact whereas the CWT has not.
Human Physiological Adaptations to Climate
1750 words
Humans are adapted to numerous ecosystems on earth. This is only possible due to how our physiological systems interact with the environment in a homeodynamic way. This allowed us to spread across the globe, far away from our ancestral home of Africa, and thusly certain adaptations evolved in those populations—which was driven by our intelligent physiology. I will touch on human cold and hot adaptations, how physiology adapts to the two climates and what this means for the populations that make up Mankind.
Physiological adaptations to Arctic climates
The human body is one of the most amazing and complex biological systems on earth. The human body lives and dies on its physiology and how it can adapt to novel environments. When Man first trekked out of Africa into novel environments, our physiology adapted so we could survive in novel conditions. Over time, our phenotypes adapted to our new climates and humans began looking different from one another due to the climatic differences in their environments.
There is a large body of work on human cold adaptation. Thermal balance in humans is maintained by “vasodilation/vasoconstriction of the skin and peripheral tissues within the so-called thermo-neutral zone” (Daanen and Lichtenbelt, 2016). Two other adaptations occur in the cold: shivering thermogenesis (ST) and non-shivering thermogenesis (NST) and one in the heat (the evaporation of sweat). Humans are not Arctic animals by nature, so, therefore, venturing into novel environments would incur new physiological adaptations to better deal with the cold.
Heat is induced by the body in cold climates by shivering (Tikuisis, Bell, and Jacobs, 1991; Daanen and Lichtenbelt, 2016). So, therefore, people in colder climates will have higher metabolisms than people in tropical environments, to generate more body heat for vital functioning. People living in Arctic environments have fewer sweat glands than people who live in the tropics. Sweating removes heat from the body, so having more sweat glands in colder climates would not be conducive for survival.
People who evolved in Arctic climates would also be shorter and have wider pelves than people who evolved in the tropics. This is seen in Neanderthals and is an example of Cold adaptations also show up in the Greenlandic Inuit due to extinct hominins like the Denisova (Fumagalli et al, 2015).
We can see natural selection at work in the Inuits, due to adaptation to Arctic climates (Galloway, Young, and Bjerregaard, 2012; Cardona et al, 2014; Ford, McDowell, and Pierce, 2015; NIH, 2015; Harper, 2015; Tishkoff, 2015). Climate change is troubling to some researchers, with many researchers suggesting that global warming will have negative effects on the health and food security of the Inuit (WHO, 2003; Furgal and Seguin, 2006; Wesche, 2010; Ford, 2009, 2012; Ford et al, 2014, 2016; McClymont and Myers, 2012; Petrasek, 2014; Petrasek et al, 2015; Rosol, Powell-Hellyer, and Chan, 2016). This Inuit are the perfect people to look to to see how humans adapt to novel climates—especially colder ones. They have higher BMIs which is better for heat retention, and larger brains with wider pelves and a shorter stature.
Metabolic adaptations also occur due to BMI, which would occur due to diet and body composition. Daanen and Lichtenbelt, (2016) write:
Bakker et al.,48 however, showed that Asians living in Europe had lower BAT prevalence and exhibited a poorer shivering and non-shivering response to cold than Caucasians of similar age and BMI. On the other hand, subjects living in polar regions have higher BMI, and likely more white fat for body energy reserves and insulation.49 This cannot be explained by less exercise,50 but by body composition51 and food intake.49
Basal metabolic rate (BMR) also varies by race. Resting metabolic rate is 5% higher in white women when compared to black women (Sharp et al, 2002). Though low cardiovascular fitness explains 25 percent of the variance in RMR differences between black and white women (Shook et al, 2014). People in Arctic regions have a 3-19 higher BMR than predicted on the basis of the polar climates they lived in (Daanen and Lichtenbelt, 2016). Further, whites had a higher BMR than Asians living in Europe. Nigerian men were seen to have a lower BMR than African-American men (Sharp et al, 2002). So, whites in circumpolar locales have a higher BMR than peoples who live closer to the equator. This has to do with physiologic and metabolic adaptations.
Blacks also show slower and lower cold induced vasodilation (CIVD) than whites. A quicker CIVD in polar climates would be a lifesaver.
However, just our physiologic mechanisms alone aren’t enough to weather the cold. Our ingenuity when it comes to making clothes, fire, and finding and hunting for food are arguably more important than our bodies physiologic ability to adapt to its present environment. Our behavioral plasticity (ability to change our behavior to better survive in the environment) was also another major factor in our adaptation to the cold. Then, cultural changes would lead to genetic changes, and those cultural changes—which were due to the cold climates—would then lead to more genetic change and be an indirect effect of the climate. The same, obviously, holds for everywhere in the world that Man finds himself in.
Physiologic changes to tropical climates
Physiologic changes in tropical climates are very important to us as humans. We needed to be endurance runners millions of years ago, and so our bodies became adapted for that way of life through numerous musculoskeletal and physiologic changes (Lieberman, 2015). One of the most important is sweating.
Sweating is how our body cools itself and maintains its body temperature. When the skin becomes too hot, your brain, through the hypothalamus, reacts by releasing sweat through tens of millions of eccrine glands. As I have covered in my article on the evolution of human skin variation, our loss of fur (Harris, 2009) in our evolutionary history made it possible for sweat to eventually cool our body. Improved sweating ability then led to higher melanin content and selection against fur. Another hypothesis is that when we became bipedal, our bodies were exposed to less solar radiation, selecting against the need for fur. Yet another hypothesis is that trekking/endurance running led to selection for furlessness, selecting for sweating and more eccrine glands (Lieberman, 2015).
Anatomic changes include long and thin bodies with longer limbs as heat dissipation is more efficient. People who live in tropical environments have longer limbs than people who live in polar environments. These tall and slender bodies are what is useful in that environment. People with long, slender bodies are disadvantaged in the cold. Further, longer, slender bodies are better for endurance running and sprinting. They also have narrower hips which helps with heat dissipation and running—which means they would have smaller heads than people in more northerly climes. Most adaptations and traits were once useful in whichever environment that organism evolved in tens of thousands of years ago. And certain adaptations from our evolutionary past are still evident today.
Since tropical people have lower BMRs than people at more northerly climes, this could also explain why, for instance, black American women, have higher rates of obesity than women of other races. They have a lower BMR and are sedentary and eat lower-quality food so food insecurity would have more of an effect on that certain phenotype. Africans wouldn’t have fast metabolisms since a faster metabolism would generate more heat.
Physiologic changes due to altitude
The last adaptation I will talk about is how our bodies can adapt to high altitudes and how it’s beneficial. Many human populations have adapted to the chronic hypoxia of high latitudes (Bigham and Les, 2014) which, of course, has a genetic basis. Adaptation to high altitudes also occurred due to the introgression of extinct hominin genes into modern humans.
Furthermore, people in the Andean mountains, people living in the highlands of Kenya and people living on the Tibetan plateau have shown that the three populations adapted to the same stress through different manners. Andeans, for instance, breathe the same way as people in lower latitudes but their red blood cells carry more oxygen per cell, which protects them from the effects of hypoxia. They also have higher amounts of hemoglobin in their blood in comparison to people who live at sea level, which also aids in counterbalancing hypoxia.
Tibetans, on the other hand, instead of having hematological adaptations, they have respiratory adaptations. Tibetans also have another adaptation which expands their blood vessels, allowing the whole body to deliver oxygen more efficiently to different parts. Further, Ethiopians don’t have higher hemoglobin counts than people who live at sea level, so “Right now we have no clue how they do it [live in high altitudes without hematologic differences in comparison to people who live at sea level]”.
Though Kenyans do have genetic adaptations to live in the highlands (Scheinfeldt et al, 2012). These genetic adaptations have arisen independently in Kenyan highlanders. The selective force, of course, is hypoxia—the same selective force that caused these physiologic changes in Andeans and Tibetans.
Conclusion
The human body is amazing. It can adapt both physiologically and physically to the environment and in turn heighten prospects for survival in most any environment on earth. These physiologic changes, of course, have followed us into the modern day and have health implications for the populations that possess these changes. Inuits, for instance, are cold-adapted while the climate is changing (which it constantly does). So, over time, when the ice caps do melt the Arctic peoples will be facing a crisis since they are adapted to a certain climate and diet.
People in colder climates need shorter bodies, higher body fat, lower limb ratio, larger brains etc to better survive in the cold. A whole slew of physiologic processes aids in peoples’ survival in the Arctic, but our ability to make clothes, houses, and fire, in conjunction with our physiological dynamicness, is why we have survived in colder climates. Tropical people need long, slender bodies to better dissipate heat, sweat and run. People who evolved in higher altitudes also have hematologic and respiratory adaptations to better deal with hypoxia and less oxygen due to living at higher elevations.
These adaptations have affected us physiologically, and genetically, which leads to changes to our phenotype and are, therefore, the cause of how and why we look different today. Human biological diversity is grand, and there are a wide variety of adaptations to differing climates. The study of these differences is what makes the study of Man and the genotypic/phenotypic diversity we have is one of the most interesting sciences we have today, in my opinion. We are learning what shaped each population through their evolutionary history and how and why certain physical and physiologic adaptations occurred.
Exercise, Longetivity, and Cognitive Ability
1650 words
The relationship between exercise and cognitive ability is important, but often not spoken about. Exercise releases many endorphins (Harber and Sutton, 1984) that help to further positive mood, have one better handle stress since sensitivity to stress is reduced after exercise; and after exercise, depression, and anxiety also decrease (Salmon, 2001). Clearly, if you’re attempting to maximize your cognition, you want to exercise. However, a majority of Americans don’t exercise (49 percent of Americans over the age of 18 do aerobic exercise whereas only 20 percent of Americans do both aerobic and muscle-strengthening exercise). The fact that we do not exercise as a country is proof enough that our life expectancy is declining (Olshansky et al, 2005), and we need to exercise—as a country—to reverse the trend.
Regular readers may know of my coverage of obesity on this blog. Understandably, a super majority of people will disregard my views on obesity and its causes as ‘pseudoscience’ or ‘SJW-ness’, that however says nothing to the data (and if anyone would like to discuss this, they can comment on the relevant articles). Since the average American hardly gets any exercise, this can lead to a decrease in cognitive functioning as less blood flows to the brain. Thus, everyone—especially the obese—needs to exercise to reach maximum genetic brain performance, lest they degenerate in cognitive function due a low-quality diet, such as a diet high in n-6 (the SAD diet), which is correlated with decreased cognition. Further, contrary to popular belief, the obese have lower IQs since around age three; obesity does not itself lower genotypic IQ, their IQ is ALREADY LOW which leads to obesity later in life due to a non-ability to delay gratification. Clearly, exercise education needs to be targeted at those with lower IQs since they have a higher chance of becoming obese in comparison to those with lower IQs (Kanazawa, 2013; 2014).
Clearly not eating well and not exercising can have negative effects on cognition. But what are the positives?
As mentioned previously, exercise releases endorphins that cause good mood and block pain. However, the importance of exercise does not stop there. Exercise also leads to faster reaction times on memory tasks and “increased levels of high-arousal positive affect (HAP) and decreased levels of low-arousal positive affect (LAP).” Exercise has important effects on people of all age groups (Hogan, Mata and Carstensen, 2013; Chodzko-Zajko et al, 2009). Further, physical exercise protects against age-related diseases and cognitive decline in the elderly by modifying “metabolic, structural, and functional dimensions of the brain that preserve cognitive performance in older adults.” (Kirk-Sanchez and McGough, 2014). Exercise is, clearly, a brain protectant during both adolsence and old age, so no matter your age if you want a high QoL living the best life possible, you need to supplement an already healthy lifestyle with strength training/cardio (of course, under doctor’s supervision).
Another important benefit to exercise is that it increases blood flow to the brain (Querido and Steele, 2007; Willie and Ainslie, 2011); however, changes in cerebral blood flow (CBF) during exercise are not associated with higher cognition (Ogoh et al, 2014). During prolonged exercise, cognition was improved when blood flow to the middle cerebral artery (MCA) was decreased. Thusly, exercise-induced changes in CBF do not preserve cognitive performance. Exercise to get blood to the brain is imperative for proper brain functioning. Our brains are vampiric, so we need to ‘feed it’ with blood and what’s the best way to ‘feed’ the brain in this context? Exercise!
Exercise also protects against cognitive degeneration in the elderly (Bherer, Erikson and Lie-Ambrose, 2013; Carvalho et al, 2014; Paillard, 2015). Further, longitudinal studies show an association between exercise and a decrease in dementia (Blondell, Hammersley-Mather and Veerman, 2014). The evidence is currently piling up showing that exercise at all ages is good cognitively, reduces mortality as well as a whole slew of other age-related cognitive diseases. The positive benefits of exercise need to be shown to elderly populations since exercise—mainly strength training—reduces the chance of osteoporosis (Layne and Nelson, 1999; Gray, Brezzo, and Fort, 2013). Moreover, elderly people who exercise live longer (Gremeaux et al, 2012). Now, if you don’t exercise, now’s looking like a pretty good time to start, right?
Finally, lack of exercise causes a myriad of deleterious diseases (Booth, Roberts, and Laye, 2014). This is due, in large part to our evolutionary novel environment (Kanazawa, 2004) which leads to evolutionary mismatches. An evolutionary mismatch, in this instance, is our obesogenic environment (Lake and Townshend, 2006). In terms of our current environment, it is evolutionary novel in comparison to our ancestral land (the Savanna; re: Kanazawa, 2004). Modern-day society is ‘evolutionarily novel’. In this case, we haven’t fully adapted (genetically) to our new lifestyles as, Gould said in Full House, our rate of cultural change has vastly exceeded Darwinian selection. Thusly, our environments that we have made for ourselves (and that we assume that heighten our QoL) actually cause the reverse, all the while top researchers are scratching their heads to figure out the answer, the problem while it’s staring them right in the face.
Our obesogenic environments have literally created a mismatch with our current eating habits and our ancestral one (Krebs, 2009). Moreover, dietary mismatches occur when cultural and technological change vastly outstrip biological evolution (Logan and Jacka, 2009). Clearly, we need to lessen the impact of our obesogenic environment we have made for ourselves so that we can live as long as possible, as well as be as cognitively sharp as possible. Thusly, if our environment causes a mismatch with our genome which in turn causes obesity, then by changing our environment to one that matches our genome, so to speak, levels of obesity should decline as our environment becomes less obesogenic while becoming like our ancestral environment (Genne-Bacon, 2014).
In sum, the evidence for the positive benefits for exercise is ever-mounting (not like you need Pubmed studies to know that exercise is beneficial). However, due to our obesogenic environments, this makes it hard for people with higher time preference to resist their urges and the result is what you see around you today. The evidence is clear: exercise leads to increased blood flow to our vampiric brains; thus it will have positive effects on memory and other cognitive faculties. So, in order to live to a ripe, old age as a healthy man/woman, hit the gym and treadmill and try staying away from evolutionarily novel things as much as possible (i.e., like processed food). When we, as a country recognize this, we can then be smarter, healthier and, above all else, have a high QoL while living a longer life. Is that not what we all want? Well hit the gym, start exercising and change your diet to one that matches our ancestors. Don’t be that guy/gal (we all know who that guy is) that jumps on the exercise train late and misses out on these cognitive and lifestyle benefits!
Note: Only with Doctor supervision, of course
References
Bherer, L., Erickson, K. I., & Liu-Ambrose, T. (2013). A Review of the Effects of Physical Activity and Exercise on Cognitive and Brain Functions in Older Adults. Journal of Aging Research,2013, 1-8. doi:10.1155/2013/657508
Blondell, S. J., Hammersley-Mather, R., & Veerman, J. L. (2014). Does physical activity prevent cognitive decline and dementia?: A systematic review and meta-analysis of longitudinal studies. BMC Public Health,14(1). doi:10.1186/1471-2458-14-510
Booth, F. W., Roberts, C. K., & Laye, M. J. (2013). Lack of Exercise Is a Major Cause of Chronic Diseases. Comprehensive Physiology. doi:10.1002/cphy.c110025
Carvalho, A., Cusack, B., Rea, I. M., & Parimon, T.,. (2014). Physical activity and cognitive function in individuals over 60 years of age: a systematic review. Clinical Interventions in Aging, 661. doi:10.2147/cia.s55520
Chodzko-Zajko WJ, Proctor DN, Fiatarone Singh MA, Minson CT, Nigg CR, Salem GJ, Skinner JS: American College of Sports Medicine position stand. Exercise and physical activity for older adults. Med Sci Sports Exerc. 2009, 41: 1510-1530. 10.1249/MSS.0b013e3181a0c95c.
Gray M., Di Brezzo R., I.L. Fort (2013) The effects of power and strength training on bone mineral density in premenopausal women. J Sports Med Phys Fitness, 53, pp. 428–436
Genné-Bacon EA, Thinking evolutionarily about obesity. Yale J Biol Med 87: 99–112, 2014
Gremeaux V, Gayda M, Lepers R, Sosner P, Juneau M, Nigam A. Exercise and longevity. Maturitas. 2012;73(4):312–7.
Harber VJ, Sutton JR. (1984) Endorphins and exercise. Sports Medicine 1: 154–174, 1984
Hogan, C. L., Mata, J., & Carstensen, L. L. (2013). Exercise holds immediate benefits for affect and cognition in younger and older adults. Psychology and Aging,28(2), 587-594. doi:10.1037/a0032634
Kanazawa, S. (2004). The Savanna Principle. Managerial and Decision Economics,25(1), 41-54. doi:10.1002/mde.1130
Kanazawa, S. (2013). Childhood intelligence and adult obesity. Obesity,21(3), 434-440. doi:10.1002/oby.20018
Kanazawa, S. (2014). Intelligence and obesity. Current Opinion in Endocrinology & Diabetes and Obesity,21(5), 339-344. doi:10.1097/med.0000000000000091
Krebs, J. R. (2009). The gourmet ape: evolution and human food preferences. American Journal of Clinical Nutrition,90(3). doi:10.3945/ajcn.2009.27462b
Lake, A., & Townshend, T. (2006). Obesogenic environments: exploring the built and food environments. The Journal of the Royal Society for the Promotion of Health,126(6), 262-267. doi:10.1177/1466424006070487
Layne, J. E., & Nelson, M. E. (1999). The effects of progressive resistance training on bone density: a review. Medicine & Science in Sports & Exercise,31(1), 25-30. doi:10.1097/00005768-199901000-00006
Kirk-Sanchez, N., & Mcgough, E. (2014). Physical exercise and cognitive performance in the elderly: current perspectives. Clinical Interventions in Aging, 51. doi:10.2147/cia.s39506
Ogoh, S., Tsukamoto, H., Hirasawa, A., Hasegawa, H., Hirose, N., & Hashimoto, T. (2014). The effect of changes in cerebral blood flow on cognitive function during exercise. Physiological Reports,2(9). doi:10.14814/phy2.12163
Olshansky, S. J., Passaro, D. J., Hershow, R. C., Layden, J., Carnes, B. A., Brody, J., . . . Ludwig, D. S. (2005). A Potential Decline in Life Expectancy in the United States in the 21st Century. New England Journal of Medicine,352(11), 1138-1145. doi:10.1056/nejmsr043743
Paillard, T. (2015). Preventive effects of regular physical exercise against cognitive decline and the risk of dementia with age advancement. Sports Medicine – Open,1(1). doi:10.1186/s40798-015-0016-x
Querido, J. S., & Sheel, A. W. (2007). Regulation of Cerebral Blood Flow During Exercise. Sports Medicine,37(9), 765-782. doi:10.2165/00007256-200737090-00002
Salmon, P. (2001). Effects of physical exercise on anxiety, depression, and sensitivity to stress. Clinical Psychology Review,21(1), 33-61. doi:10.1016/s0272-7358(99)00032-x
Willie, C. K., & Ainslie, P. N. (2011). Cool head, hot brain: cerebral blood flow distribution during exercise. The Journal of Physiology,589(11), 2657-2658. doi:10.1113/jphysiol.2011.209668
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