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Man the Athlete

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Homo nerdicus or Homo athleticus? Which name more aptly describes Man? Without many important adaptations incurred throughout our evolutionary history, modern Man as you see him wouldn’t be here today. The most important factor in this being our morphology and anatomy which evolved due to our endurance running, hunting, and scavenging. The topics I will cover today are 1) morphological differences between hominin species and chimpanzees; 2) how Man became athletic and bring up criticisms with the model; 3) the evolution of our aerobic physical ability and brain size; 4) an evolutionary basis for sports; and 5) the role of children’s playing in the evolution of human athleticism.

Morphological differences between Man and Chimp

Substantial evolution in the lineage of Man has occurred since we have split from the last common ancestor (LCA) with chimpanzees between 12.1 and 5.3 mya (Moorjani et al, 2016; Patterson et al, 2006). One of the most immediate differences that jump out at you when watching a human and chimpanzee is such stark differences in morphology, in particular, how we walk (pelvic differences) as well as our arm length relative to our torsos. Though we both evolved to be proficient at abilities that had us become evolutionarily successful in the environments we found ourselves in, one species of primate went on to become the apes the took over the world whereas the chimps continued life as the LCA did (as far as we can tell). The evolution of our athleticism is why we have a lean body with the right morphology for endurance running and associated movements. In fact, the evolution of our brain size hinged on a reduction in our fat depots (Navarette, Schaik, and Isler, 2011).

One of the largest differences you can see between the two species is how we walk. Chimps are “specially adapted for supporting weight on the dorsal aspects of middle phalanges of flexed hand digits II–V” (Tuttle, 1967). Meanwhile, humans are specifically adapted for bipedality due to the change in our pelvis over the course of our evolution (Gruss and Schmitt, 2015). Due to staying more arboreal than venturing on the ground, chimp morphology over the course of the divergence became more and more adapted to life in the trees.

Our modern gait is associated with physiologic and anatomic adaptations throughout our evolution, and are not ‘primitive retentions’ from the LCA (Schmitt, 2003). There are very crucial selective pressures that need to be looked at to see which selection pressures caused us to become athletes. Parts of Austripolithicenes still live on in us today, most notably in our lower leg/foot (Prang, 2015). Further, our ancestor, the famous Lucy had the beginnings of a modern pelvis, which was the beginning of the shift to the more energetically efficient bipedality, one thing that fully separates Man from the rest of the animal kingdom.

Of course, no conversation about human evolution would be complete without talking about Erectus. Analysis of 1.5 million-year-old footprints shows that Erectus was the first to have a humanlike weight transfer while walking, confirming “the presence of an energy-saving longitudinally arched foot in H. Erectus.” (Hatala et al, 2016). We have not yet discovered a full Homo erectus foot, but 1.5 million-year-old footprints found in Kenya show that whatever hominin made those prints had a long, striding gait with a full arch (Steudel-Numbers, 2006; Bennett et al, 2009). The same estimates from Steudel-Numbers (2006) show that Erectus nearly halved its travel costs compared to australopithecines. This is due to a longer stride which was much more Manlike than apelike due to a humanlike pelvis and gluteus maximus (Lieberman et al, 2006).

However, the most important adaptations that Erectus evolved was the ability to keep cool while walking long distances. Loss of hair loss specifically allowed individuals to be active in hot climates without overheating. Our ancestors’ hair loss facilitated sweating (Ruxton and Wilkinson, 2011b), which allowed us to become the proficient hunters—the athletes—that we would become. There is also thermoregulatory evidence that endurance running may have been possible for Homo erectus, but not any other earlier hominin (Ruxton and Wilkinson, 2011a) which was the beginnings of our selection to become athletes. The evidence reviewed in Ruxton and Wilkinson (2011a) shows that once hair loss and sweating ability reached human levels, thermoregulation was then possible under the midday sun.

Moreover, our modern gait and bipedalism is 75 percent less costly than quadrupedal/bipedal walking in chimpanzees (Sockel, Raichlen, and Pontzer, 2007), so this extra energy that was conserved with our physiologic and anatomic adaptations due to bipedalism could have gone towards other pertinent metabolic functions—like fueling a bigger brain (more energy could be used to feed more neurons).

Born to run

Before getting into how we are able to run so efficiently, I need to talk about what made it possible for us to be able to have the energy to sustain our distance running. That one thing is eating cooked food (meat). This one seemingly simple thing is the ‘prime mover’ so to speak, of our success as athletes. Eating cooked food significantly increases the amount of energy obtained during digestion. That we could extract more energy out of cooked food—no matter what type of food it was—can not be overstated. This is what gave us the energy to hunt and scavenge. We are, of course, able to hunt/scavenge while fasted, which is an extremely useful evolutionary adaptation which increases important hormones to have us search for food. The hormones released during a fasted state aid in human physiologic/metabolic functioning allowing one who is searching for food more heightened sensibilities.

We are evolutionarily adapted to be endurance runners. Endurance running is defined as the ability to run more than 5 km using aerobic metabolism (Lieberman and Bramble, 2007). Since we are poor sprinters, the idea is that our body has evolved for walking. However, numerous anatomical changes in our phenotypes in comparison to our chimp ancestors have left us some clues. In the previous section, I talked about physical changes that occurred after Man and Chimp diverged, well those evolutionary changes are why we evolved to be athletic.

Endurance running first evolved, most likely due to scavenging and hunting (Lieberman et al, 2009). Through natural selection—survival of the ‘good enough’, those who had better physiologic and anatomic adaptations could reach the animal carcass before other scavengers like vultures and hyenas could get to it. Over time, this substantially changed how we would look. Numerous physiologic changes in our lineage attest to the evolution of our endurance running. The nuchal ligament, as well as the radius of the semicircular canal is larger in Homo sapiens than in chimpanzees or australopithecines. This stabilizes our head while running—something that our ancestors could not do because they didn’t have a canal our size (Bramble and Lieberman, 2004).

Skeletal evidence that points to our evolution as athletes consists of (but not limited to):

  • The Nuchal ligament—stabilizes the head
  • Shoulder and head stabilization
  • Limb length and mass (we have legs longer than our torsos which decreases energy used)
  • Joint surface (we can absorb more shock when our feet hit the ground due to a larger surface area)
  • Plantar arch (generates spring for running but not walking)
  • Calcaneal tuber and Achilles tendon (shorter tuber length leads to a longer Achilles heel stretch, converting more kinetic energy into  elastic energy)

So people who had anatomy closer to this in our evolutionary past had more of a success of getting to that animal carcass, divvying it amongst his family/tribe, ensuring the passage of his genes to the next generation. Man had to be athletic in order to be able to run for long distances. Where this would have come in handy the most would have been the Savanna in our ancestral past. Man could now use persistence hunting—chasing animals in the heat of the day—and kill them when they tired out. The evolutionary adaptation sweating due to the loss of our fur is the only reason this is possible.

One of the most important adaptations for endurance running is thermoregulation. All humans are adapted for long range locomotion rather than speed and to dump rather than retain heat (Lieberman, 2015). This is one of the most important adaptations we evolved that had us become successful endurance runners. We could chase down prey and wait for our prey to become exhausted/overheat and then we would move in for the kill. Of course, intelligence and sociality come into play as we needed to create hunting bands, but without our superior endurance running capabilities—that no other animal in the animal kingdom has—we would have gone down a completely different evolutionary path than the one we went down. Our genome has evolved to support endurance running (Mattson, 2012). Since there is an association between too much sitting and all-cause mortality (Biddle et al, 2016), this is yet more evidence that we evolved to be mobile, not sedentary hominins.

Further evidence that we evolved to be athletic is in our hands. When you think about our hands and how we can manipulate our environments with them—what sets us apart from every other species—then, obviously, in our evolutionary past, those who were more successful would have had a higher chance of reproducing. Aggressive clubbing and throwing are thought to be one of the earliest hominin specializations.  If true, then those who could club and throw best would have the best chance of passing their genes to the next generation, thusly selecting for more efficient hands (Young, 2003). While we may have evolved more efficient hands over time warring with other hominins, some are more prone to disk herniation.

Plomp et al (2015) propose the ‘ancestral shape hypothesis’ which is derived from studying bipedalism. They propose that those who are more prone to disk herniation preferentially affects those who have vertebrae “towards the ancestral end of the range of shape variation within H. sapiens and therefore are less well adapted for bipedalism” (Plomp et al, 2015). One of the most amazing things they discovered was that humans with signs of intervertebral disc herniation are “indistinguishable from those of chimpanzees.” Of course, due to this, we should then look towards evolutionary biology in regards to a lot of human ailments (which I have also argued here on dietary evolutionary mismatches as well as on obesity).

Of course there are some naysayers arguing that endurance running didn’t drive our evolution. He wrongly states that it’s about what drove the evolution of our bipedalism; however, what the endurance running hypothesis argues is that there are certain physiologic and anatomic changes that only could have occurred from endurance running. Better endurance runners got selected for over time, leading to novel adaptations that stayed in the gene pool and got selected for. One thing is a larger gluteus maximus. A humanlike pelvis is found in the fossil record as far back as 1.9 mya in Erectus (Lieberman et al, 2006). Furthermore, longer toes had a larger mechanical cost, and were thusly selected against, which also helped in the evolution of our endurance running (Rolian et al, 2009). All in all, there are too many adaptations that our bodies have that can only be explained by adapting to endurance running. Just because we may have gotten to the weaker animals sometimes doesn’t falsify the hypothesis; Man still needed to sweat and persist in the hot mid-day temperatures chasing prey.

Brain size and aerobic physical capacity

When speaking about the increase in our brain size/neuronal count, fire/cooking, the social brain hypothesis, and other theories are brought up first. Erectus had a lot of humanlike qualities, including the ability to control/use fire (Berna et al, 2012), and the appearance of our modern gait/stride which first appeared in Erectus (Steudel-Numbers, 2006; Bennet et al, 2009). This huge change also occurred around the time our lineage began cooking meat/using fire. Without the increased energy from cooking, we wouldn’t be able to hunt for too long. However, we do have very important specific adaptations during a fasted state—the release of hormones such as catecholamines (adrenaline and noradrenaline) which have as react faster to predators/possible prey. Though, a plant-based diet wouldn’t cut it in regards to our daily energy requirements to feed our huge brain with a huge neuronal count (Fonseca-Azevedo and Herculano-Houzel, 2012). Cooked meat is the only way we’d be able to have enough energy required to hunt game.

What kind of an effect did it have on our cranial capacity/evolution?

Four groups of mice selectively bred for high amounts of “voluntary wheel-running”, ran 3 times further than the controls which increased Vo2 max in the mice. Those mice had higher levels of BDNF (Brain Derived Neurotrophic Factor) several days after the experiment concluded as well as also showing greater cell creation in the hippocampus when allowed to run compared to the controls. In two lines of selected mice, the hormone VEGF (Vascular Endothelial Growth Factor) which was correlated with higher muscle capillary density compared to controls. This shows that the evolution of endurance running in mice leads to important hormonal changes which then affected brain growth (Raichlen and Polk, 2012).

The amount of oxygen our brains use increased by 600 percent compared to 350 percent for our brain size over the course of our evolutionary history. This is important. What would cause an increase in oxygen consumption to the brain? Endurance running. There was further selection in our skeleton for endurance running in our morphology such as the semicircular canal radii. The first humanlike semicircular canal radii were found in Erectus (Spoor, Wood, and Zonneveid, 1994). This meant that we had the ability for running and other agile behaviors which were then selected for. There is also little to no activation of the gluteus medius while walking (Lee et al, 2014), implying that it evolved for more efficient endurance running.

Controlling for body mass in humans, extinct hominins and great apes, Raichlen and Polk (2012) found significant positive correlations with encephalization quotient and hindlimb length (0.93), anterior and posterior radii (0.77 and 0.66 respectively), which support the idea that human athletic ability is tied to neurobiological evolution. A man that was a better athlete compared to another would have a better chance to pass on his genes, as physical fitness is a good predictor of biological fitness. Putting this all together, selection improved our aerobic capacity over our evolutionary history by specifically altering signaling systems responsible for metabolism and oxygen intake (BDNF, VEGF, and IGF-1 (insulin-like growth factor 1), responsible for the regulation of growth hormone), which are important for blood flow, increased muscle capillary density, and a larger brain.

Putting this all together, selection improved our aerobic capacity over our evolutionary history by specifically altering signaling systems responsible for metabolism and oxygen intake (BDNF, VEGF, IGF-1). More evidence is needed to corroborate Raichlen and Polk’s (2012) hypothesis. However, with what we know about aerobic capacity and the hormones that drive it and brain size, we can make inferences based on the available data and say, with confidence, that part of our brain evolution was driven by our increased aerobic capacity/morphology, with the catalyst being endurance running. Though with our increased proclivity for athleticism and endurance running, when we became ‘us’, this just shifted the competition and athletic competition—which, hundreds of thousands/millions of years ago would mean life or death, mate or no mate, food or no food.

Clearly, without the evolution of our bipedalism/athleticism we wouldn’t have evolved the brains we have and thus we would be something completely different today.

Sport and evolutionary history

We crowd into arenas to watch people compete against each other in athletic competition. Why? What are the evolutionary reasons behind this? One view is that sport (and along with it playing) was a way for men to get practice hunting game, with playing also affecting children’s ability to assess the strength of others (Lombardo, 2012).

In an evolutionary context, sports developed as a way for men to further develop skills in order to better provide for his family, as well as assessing other men’s physical strength so he can adapt his fighting to how his opponent fights in a possible future situation. Men would then be selected for these advantageous traits. You see people crowd into arenas to watch their favorite sports teams. We are ‘wired’ to like these types of competitions, which then leads to more competition. Since we evolved to be athletes, then it would stand to reason that we would like to watch others be athletic (and hit each other as hard as they can), as a type of modern-day gladiator games.

Better hunters have better reproductive success (Smith, 2004). Further, hunter-gatherer men with lower-pitched voices have more children, while men with higher-pitched voices had higher child mortality rate (Apicella, Feinberg, and Marlowe, 2007). This signals that the H-G men with more children have higher testosterone than others, which then attracts more women to them. Champion athletes, hunters, and warriors all obtain high reproductive success. Women are sexually attracted to certain traits, which events of human athleticism show. However, men follow sports more closely than women (Lombardo, 2012), and for good reason.

Men may watch sports more than women since, in an evolutionary context, they may learn more about potential allies and who to steer clear from because they would get physically dominated. Further, men could watch the actions of others at play and mimic their actions in an attempt to gain higher status with women. Another reason is a man’s character: you can see a man’s character during sports competition and by watching one’s actions closely during, for instance, playing, you can better ascertain their motivations during life or death situations. Men may also derive thrills from watching “idealized men” perform athletic activities. These are consistent with Lombardo’s (2012) male lek hypothesis, “where male physical prowess and the behaviors important in conflict and cooperation are displayed by athletes and evaluated primarily by male, not female, spectators.”

Testosterone changes based on whether one’s favorite sports team wins or loses (Bernhardt et al, 1998). This is important. Testosterone does change under stressful/group situations. Testosterone is also argued to have a role in the search for, and maintenance of social status (Eisenegger, Haushofer, and Fehr, 2011). Testosterone responses to competition in men are also related to facial masculinity (Pound, Penton-Voak, and Surrin, 2009). Male’s physical strength is also signaled through facial characteristics of dominance and masculinity, considered attractive to women (Fink, Neave, and Seydel, 2007). Since testosterone fuels both competition, protectiveness and confidence (Eisenegger et al, 2016), a woman would be attracted to a man’s athleticism/strength, which would then be correlated with his facial structure further signaling biological fitness to possible mates. Testosterone doesn’t cause prostate cancer, as is commonly stated (Stattin et al, 2003; Michaud, Billups, and Partin, 2015). Testosterone is a beneficial hormone; you should be worried way more about low T than high T. Further, young men interacting with similar young men increases testosterone while interacting with dissimilar men decreases testosterone (DeSoto et al, 2009). This lends credence to the hypothesis that testosterone raises in response to male-male competition.

Since testosterone is correlated with the above traits, and since athletes have higher testosterone than non-athletes (Wood and Stanton, 2011) then certain types of males would be left in the dust. Athleticism can be looked at as a way to expend excess energy. Those with more excess energy would be more sexually attractive to women and mating opportunities would increase. This is why it’s ridiculous to believe that we evolved to be the ‘nerds’ of the animal kingdom when so much of our evolutionary success has hinged on our athleticism and superior endurance running and other athletic capabilities.

Playing

Child’s play is how children feel out the world in a ‘setting’ in which there are no real-world consequences so they can get a feel for how the world really is. Human babes are born helpless, yet with large heads. Natural selection has lead to large brains to care for children, causing earlier childbirths and making children more helpless, which selected for higher intelligence causing a feedback loop (Piantadosi and Kidd, 2016). They show that across the primate genera, the helplessness of an infant is an extremely strong predictor of adult intelligence.

Indeed, a lot of the crucial shaping of our intelligence and motor capabilities are developed in our infancy and early childhood, which we have over chimpanzees. Blaisdell (2015) defines play as: “an activity that is purposeless in that it tends to be detached from the outcome, is imperfect from the goal-directed form of the activity, and that tends to occur when the individual is in a non-stressed state.” Playing is just a carefree activity that children do to get a feel for the world around them. During this time, skills are honed that, in our ancestral past, allowed us to survive and prosper during times of need (persistence hunting, scavenging, etc).

Anthropological evidence also suggests that the existence of extended childhood in humans adapted to establish the skills and knowledge needed to be a proficient hunter-gatherer. Since there are no real-world outcomes to playing (other than increased/decreased pride), a child can get some physical experience without suffering the real life repercussions of failing. Studies of hunter-gatherers show that play fosters the skills needed to be proficient in tool-making and tool-use, food provisioning, shelter, and predator defense. Play time also hones athletic ability and the brain-body connection so one can be prepared for a stressful situation. In fact, children’s fascination with ‘why’ questions make them ‘little philosophers’, which is an evolutionary adaptation to prepare for possible future outcomes.

Think of play fighting. While play fighting, the outcome has no important real life applications (well, the loser’s pride is hit) and what is occurring is the honing of skills that are useful to survival. During our ancestral evolution, play fighting between brothers could have honed the skills needed during a life our death situation when another band of humans was encountered. As you begin to associate certain movements with certain events, you then become better prepared subconsciously for when novel situations occur. The advantage of an extended childhood with large amounts of play time allow the brain and body to make certain connections between things and when these situations arise during a life or death situation, the brain-body will already have the muscle memory to handle the situation.

Conclusion

Studying our evolution since the divergence between Man and chimp, we can see the types of adaptations that we have incurred over our evolutionary history that have lead to us being specifically adapted for long-term endurance running. The ability to sweat, which, as far as we know began with Erectus, was paramount in our history for thermoregulation. Looking at the evolution of our pelvis, toes, gluteal muscles, heads, shoulders, brains, etc all will point to how they are adapted to a bipedal ape that is born to run—born to be an athlete. Without our athleticism, our intelligence wouldn’t be possible. We have a brain-body connection, our brain isn’t the only thing that drives our body, the two work in concert giving each other information, reacting to familiar and novel stimuli. That’s for another time though.

We didn’t evolve to be Homo nerdicus, we evolved to be Homo athleticus. This can be seen with how exercise has such a huge impact on cognition. We can further see the relationship between our athletic ability and our cognition/brain size. Without the way our evolution happened, Man—along with everything else you see around you—would not be here today. In a survival situation—one in which society completely breaks down—one who has better control over his body and motor functions/capabilities will outlast those who do not. Ultimate and conscious control over our bodies, reacting to stimuli in the environment is fostered in our infancy during our play time with others. Playing allows an individual to get experience in a simulated event, getting important muscle memory to react to future situations. The brain itself, of course, is being molded during playing as well. This just attests to the large part that playing has on cognition, survival skills and athletic ability over our evolutionary history.

Aerobic capacity throughout our evolutionary history beginning with Erectus was paramount for what we have become today. Without the evolution of certain muscles like our gluteus maximus along with certain appendages that gave us the ability to trek/run long distances, we would have lost a very important variable in our brain evolution. Aerobic activity increases blood flow to the brain and so the more successful endurance runners/hunters would increase their biological fitness (as seen in Smith, 2004) and thusly those who were more athletically successful would have more children, increasing selection for important traits for endurance running/athleticism throughout our evolutionary history.

We still play sports today since we love competition. Testosterone fuels the need for competition and sports is the best way to engage in competition in the modern day. Women are much more attracted to men with higher levels of testosterone which in turn means a more masculinized face which signals dominance and testosterone levels during competition. Women are attracted to men with higher levels of testosterone and a more masculinized face. This just so happens to mirror athletes, who have both of these traits. However, being in top physical condition is not enough; an athlete must also have a strong mental background if, for instance, they wish to break world records (Lippi, Favaloro, and Guidi, 2008).

The evolution of human playing ties this together. These sports competitions that we have made hearken back to our evolutionary past and show who would have fared best in the past. When we play, we are feeling our competition and who we can possibly make allies with/watch out for due to their actions during playing. One would also see who he would likely need to avoid and form an alliance with as to not get on his bad side and prevent a loss of status in his band. This is what it really comes down to—loss of status. Higher-status men do have higher levels of testosterone, and by one losing to a more capable person, they show that they aren’t fit to lead and they fall in the social hierarchy.

To fully understand human evolution and how we became ‘us’ we need to understand the evolution of our morphology and how it pertains to things such as our cognition and overall brain size and what advantages/disadvantages it afforded us. Whatever the case may be, it’s clear that we have evolved to be athletic and any change in that makeup will lead to a decrease in quality of life.

Homo athleticus, not Homo nerdicus, best describes Man.

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Prang, T. C. (2015). Rearfoot posture of Australopithecus sediba and the evolution of the hominin longitudinal arch. Scientific Reports,5, 17677. doi:10.1038/srep17677

Raichlen, D. A., & Polk, J. D. (2012). Linking brains and brawn: exercise and the evolution of human neurobiology. Proceedings of the Royal Society B: Biological Sciences,280(1750), 20122250-20122250. doi:10.1098/rspb.2012.2250

Rolian, C., Lieberman, D. E., Hamill, J., Scott, J. W., & Werbel, W. (2009). Walking, running and the evolution of short toes in humans. Journal of Experimental Biology,212(5), 713-721. doi:10.1242/jeb.019885

Ruxton, G. D., & Wilkinson, D. M. (2011). Avoidance of overheating and selection for both hair loss and bipedality in hominins. Proceedings of the National Academy of Sciences,108(52), 20965-20969. doi:10.1073/pnas.1113915108

Ruxton, G. D., & Wilkinson, D. M. (2011). Thermoregulation and endurance running in extinct hominins: Wheeler’s models revisited. Journal of Human Evolution,61(2), 169-175. doi:10.1016/j.jhevol.2011.02.012

Schmitt, D. (2003). Insights into the evolution of human bipedalism from experimental studies of humans and other primates. Journal of Experimental Biology,206(9), 1437-1448. doi:10.1242/jeb.00279

Schulkin, J. (2016). Evolutionary Basis of Human Running and Its Impact on Neural Function. Frontiers in Systems Neuroscience,10. doi:10.3389/fnsys.2016.00059

Smith, E. A. (2004). Why do good hunters have higher reproductive success? Human Nature,15(4), 343-364. doi:10.1007/s12110-004-1013-9

Sockol, M. D., Raichlen, D. A., & Pontzer, H. (2007). Chimpanzee locomotor energetics and the origin of human bipedalismProceedings of the National Academy of Sciences,104(30), 12265-12269. doi:10.1073/pnas.0703267104

Spoor, F., Wood, B., & Zonneveld, F. (1994). Implications of early hominid labyrinthine morphology for evolution of human bipedal locomotion. Nature,369(6482), 645-648. doi:10.1038/369645a0

Stattin, P., Lumme, S., Tenkanen, L., Alfthan, H., Jellum, E., Hallmans, G., . . . Hakama, M. (2003). High levels of circulating testosterone are not associated with increased prostate cancer risk: A pooled prospective study. International Journal of Cancer,108(3), 418-424. doi:10.1002/ijc.11572

Steudel-Numbers, K. L. (2006). Energetics in Homo erectus and other early hominins: The consequences of increased lower-limb length. Journal of Human Evolution,51(5), 445-453. doi:10.1016/j.jhevol.2006.05.001

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Testosterone and Society

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In my last post on testosterone, I showed how the alarmism against having high testosterone is blown out of proportion. The hormone testosterone was extremely important in our evolutionary history, with skull changes that are affected by testosterone changing, indicating that it’s a cause of the rise of civilization. By looking at the skulls and skeletons of our hominin ancestors, we can infer how high the testosterone was due to changes in their skeletons over time. It seems that a decrease in testosterone was partly responsible for the advent of civilization, but too low of a dip is causing problems in the West.

Testosterone on its own is very important for male fertility, and confidence with there being no evidence showing causation in regards to prostate cancer. There are, however, large increases and dips and testosterone throughout evolutionary history. This can be inferred from looking at the skeletal remains of our ancestors.

One such study was completed by Cieri et al (2014). Cieri et al found that there was substantial feminization of Homo sapiens facial anatomy. Most notably there were reductions in average brow projection and the shortening of the upper facial skeleton. If you have knowledge of testosterone and its effects on the body, this is not surprising. Relaxing either testosterone or androgen sensitivity will cause softer, more feminized facial features over time. They argue that changes in craniofacial morphology reflects reduction in circulating levels of testosterone, “or reduced androgen receptor densities”, which, they argue “reflect the evolution of enhanced social tolerance since the Middle Pleistocene.”

The reduction in human craniomorphology coincides with larger populations from the Agricultural Revolution, which meant greater social tolerance and reduced aggression towards the group. Due to this, people were more altruistic to each other. Men that were more altruistic and had more pro-social behaviors, for instance, would be able to trade with other men in the band, which became sort of a fallback when they couldn’t forage any food. Over time, those men who could cooperate better (and had more feminized craniomorphology due to less circulating testosterone/androgen receptors).

Due to the selection of more pro-social behaviors, humans started becoming less aggressive and facial features became more feminized (due to less circulating testosterone/androgen receptors). Testosterone itself is correlated with aggressive behavior (Olweus et al, 1988) so with the selection against testosterone due to people who were more altruistic makes sense in this evolutionary context.

Cieri et al argue a good case—that the beginnings of behavioral modernity was due to selection against aggressive behavior, shifted towards pro-sociality. The fact that this began to occur around the Agricultural Revolution is no coincidence, in my opinion.

However, there seems to be a level of testosterone that a civilization needs to remain standing. Testosterone levels have reduced in the past two decades. Men are becoming more feminized, partly due to the environments we have constructed for ourselves. It’s in part due to the foods we eat/what we eat out of that is causing the drop. For instance, imagine being in an environment that destroys human testosterone levels. For instance, let’s say that a lot of the food we eat is made with/stored in a lot of BPA-containing storage. Over time, this would cause differing gene expression. People who are eating these testosterone-lowering foods will have children and, theoretically, pass on the genetically expressed genes to their children, in an epigenetic transference. Since those genes would then be advantageous in the environments we have constructed for ourselves, they would then get selected for. Once enough people get the gene in the population then it will reach fixation. That gene will then get selected in that population. If that gene is one that lowers testosterone, you will then begin to have a more feminized population (like we are seeing now, with men having lower levels of testosterone now than we did twenty years ago).

As I argued in my previous article on testosterone, what Rushton described in his 1988 paper was the Graeco-Roman elite did not breed due to having less circulating testosterone. As I have covered, low testosterone is correlated with having fewer children. As Rushton hypothesized, the elite did not breed while the lower classes did. We can look at it today and look at the ‘elite’ as upper-middle/upper class and look at the lower class, as, well the lower class. We do see the testosterone/class relationship today, with higher classes having lower levels of testosterone, vice versa for lower classes (Dabbs and Morris, 1990).

When looking at testosterone changes over time, fertility rates need to be looked at. Testosterone is down across the board all over the Western hemisphere, and it just so happens that the West is in a fertility crisis (with Europe having the lowest fertility in the world). Not surprisingly, testosterone is taking a dip in the West which is then having a negative effect on testosterone levels. This is due, partly, to the anti-testosterone environments that we have unknowingly (?) constructed for ourselves. To mediate these problems, we need to construct environments that keep testosterone levels raised as to side-step all of the horrible health problems associated with low testosterone, especially later in life.

So, since testosterone is the dominance/confidence/stress hormone, it’s clear that most men don’t put themselves into situations where the hormone would be heightened by the body. Testosterone levels do change throughout the day and depending on events that occur. If you’re around a lot of rowdy people, your testosterone will raise in response to the action around you. Testosterone rises significantly when in large groups and others around are committing violence and being destructive. This is natural, though. When this occurs, you’ll be at the ready for anything that happens, there will be no surprises. It’s a stress hormone, in that it rises mostly in stressful situations.

For society to form, there needed to be somewhat of a testosterone reduction throughout our evolutionary history. This allowed us to trade with each other and so, altruistic behaviors then were selected for. However, too much of a testosterone reduction within single populations leads to lower fertility, and, eventually, the fall of societies due to lower fertility rates. The key here is that we need to construct environments that encourage higher levels of testosterone. If something is not done, then Western society will fall sooner, rather then later (all things eventually come to an end; nothing lasts forever).

The Testosterone and Fertility Conundrum: A Western Perspective

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Some people are scared of testosterone. This is no surprise, since a super-majority of people have no background in the human sciences. I’m sure plenty men know what it’s like to have low testosterone, just like some men know what it’s like to have higher T levels than average. What is the optimum level of testosterone? Why are some people scared of this hormone?

Rushton (1997) posited that r/K Selection Theory could be used to classify the races of Man on a spectrum, going from r-selection (having many children but showing little to no parental care) to K-selection (having fewer children but showing a lot of parental care). He stated that the traits of the races were also on the r/K spectrum, with the races having stark differences in morphology. Rushton’s application of r/K theory to humans isn’t completely wrong, though I do have some problems with some of his claims, such as his claims that the races differ in average penis size. He contends that testosterone is the cause for higher crime rates for black Americans and higher rates of prostate cancer in black Americans compared to white Americans.

However, in 2014, Richard et al showed that when controlling for age, blacks had 2.5 to 4.9 percent more testosterone than whites, on average. This cannot explain racial differences in prostate cancer. However, some people may emphatically claim that the races differ in average testosterone, with blacks having 13 percent higher free testosterone than whites on average. The citation that gets used the most to prove that blacks supposedly have higher testosterone than whites is Ross et al (1986), which is based on a sample of 100 people (50 black, 50 white). He claims that it’s when T levels are higher, so it’s a ‘better study’ even though the sample leaves a lot to be desired. A much more robust study showed that the difference was negligible, and not enough to account for the differential prostate cancer rates between the races.

Rohrmann et al (2007) show that there are no differences in circulating testosterone between blacks and whites in a nationally representative sample of American men. Mexicans had the highest levels. There were, however, B-W differences in estradiol production. They couldn’t confirm the other studies that stated that blacks had higher testosterone, possibly due to variations in age or using non-representative samples (that’s the culprit). Their nationally representative sample showed there was no difference in testosterone between blacks is whites, while the meta-analysis showed by Richard et al (2014) showed the difference was negligible at 2.5 to 4.9 percent higher rate of testosterone which doesn’t explain why blacks have a higher rate of acquiring prostate cancer.

The much more likely culprit for blacks having higher rates of prostate cancer, as I have written about before, are environmental factors. The two main factors are receiving less sunlight and diet. There is no evidence that higher levels of testosterone lead to prostate cancer (Michaud, Billups, and Partin, 2015). Contrary to those who say that higher levels of T cause prostate cancer, there is growing evidence that lower levels of T lead to prostate cancer (Park et al, 2015). Put simply, there is no evidence for testosterone’s supposed impact on the prostate (Stattin et al, 2013).

Differences in androgen/androgen receptors have been explained as a cause for racial differences in prostate cancer (Pettaway, 1999), however, these results haven’t been consistent (Stattin et al, 2003) and these differences in circulating androgen may possibly be explained by differences in obesity between the two populations (Gapstur et al, 2002; also see my posts on obesity and race).

Due to the ‘testosterone scare’, some people may believe that having low T is a ‘good thing’, something that’s preferred over being a high T savage. However, testosterone and the androgen receptor gene polymorphism are both associated with competitiveness and confidence in men (Eisenegger et al, 2016) and a reduced risk of cardiovascular disease in elderly men (Ohlsson et al, 2011). Obviously, lower testosterone is related to less overall confidence. People who have the thought in their head that testosterone is a ‘bad hormone’ will believe the negativity about it in the media and popular headlines.

Testosterone alone does not cause violence, but it does cause men to be socially dominant. Testosterone has been shown to increase in the aggressive phases of sports games and when shown artificial humans made to invoke physiologic responses, leading some researchers to argue that testosterone should be classified as a stress hormone. Testosterone does change based on watching one’s favorite soccer team winning or losing in a sample of 21 men (Bernhardt et al, 1998), lending some credence to the claim that testosterone is and should be classified as a stress hormone. Also of interest is that men who administered high levels of testosterone did not report higher levels of aggression (Batrinos, 2012).

I’ve heard some people literally say that having low testosterone is ‘a good thing’. People say this out of ignorance. There are a whole slew of problems associated with low testosterone, including but not limited to: insulin resistance in diabetic men (Grossmann et al, 2008); metabolic syndrome (Tsuijimura et al, 2013); muscle loss (Yuki et al, 2013); stroke and transient ischemic attack (a mini-stroke; Yeap et al, 2009); associated with elevated risk for dementia in older men (Carcaillon et al, 2014); myocardial infarction (heart attack) in diabetic men (Daka et al, 2015) etc. So it seems that the fear of testosterone from those in the anti-testosterone camp are largely blown out of proportion.

Testosterone is also a ‘food’ for the brain, with low levels being related to mental illness, sexual dysfunction, lower quality of life and cognitive impairment (Moffat et al, 2011) in both sexes (Ciocca et al, 2016). Noticed in both men in women with testosterone deficits were: cognitive impairment (reduction of working memory, episodic memory, processing speed, visual-spatial functioning and executive performance); a decrease in sexual activity; anxiety, schizophrenia, depression and stress; and alterations in cortical thickness in the brain. The fact that testosterone is so heavily important to the body’s central functioning is extremely clear. This is why it’s laughable that some people would be happy and brag about having low testosterone.

I recently came across a book called The Testosterone Hypothesis: How Hormones Regulate the Life Cycles of Civilization. Barzilai’s main premise is that the rise and fall of the West is mediated by the hormone testosterone, and due to lower testosterone levels this is one large reason for what is currently occurring in the West. The book has an extremely interesting premise. Barzilai’s hypothesis does line up with the declining levels of testosterone in America (Travison et al, 2007) though other research shows no decline in American testosterone levels from the years 88-91 to 99-04 (Nyante et al, 2007). Moreover, men who had higher level of n-6 in their blood then n-3 were far more likely to be infertile (Safarinejad et al, 2010) a marker of low testosterone (Sharpe, 2012). The ratio of n-6 to n-3 from the years 1935 to 1939 were 8.4 to 1, whereas from the years 1935 to 1985, the ratio increased to about 10 percent (Raper et al, 1992). The ratio of n-6 to n-3, on top of lowering sperm count (which is correlated with testosterone) also has negative effects on male and female cognitive ability (Lassek and Gaulin, 2011).

Barzilai’s research also corroborates Rushton’s (1986) theory of why there are lower birthrates for Europeans around the world. Rushton stated that this cycle has been noticed throughout history, with empires rising and falling due to differential birthrates between the ruling class and the ruled. Rushton also hypothesized that the cultures and gene pools associated with the Graeco-Roman empire were “evolutionary dead ends” (Rushton, 1986: 148). Knowing what we now know about the relationship between cognitive ability, testosterone, and fertility, we now have a plausible hypothesis for Rushton’s hypothesis and one of the (many) reasons why the Graeco-Roman empire collapsed. Rushton further hypothesized that the cause for lower fertility in European populations “may be partly mediated by a psychological process in which the desire to be in control of both oneself and one’s environment is taken to an extreme.” Of course there’s a good chance that this psychological process is mediated/influenced by testosterone.

Europe is the continent with the lowest fertility (ESHRE Capri Workshop Group, 2010). Testosterone has declined in Europe as a whole (Rivas et al, 2014), and this is a strong cause for the lower birthrates in Europe (along with genetic reasons) and in Finland (Perheentupa et al, 2013). The introduction of Westernized diets lowers testosterone, so this is no surprise that a reduction is seen in countries that begin to consume a Western diet. Another probable cause for lower testosterone/fertility in Europe at the moment is the large number of European men that died in WWI and WWII. Those that were more willing to fight died, meaning there was less of a chance he spread his genes. So, over time, this lead to the current cucking of Europe that we are now witnessing.

Testosterone is also hypothesized to have driven evolution (Howard, 2001). Testosterone is such an important part of human evolution and development, so much so that if we had a lower level of the hormone all throughout our evolution that we would be a different species today. Testosterone is needed for sexual functioning, good mental and brain health, fertility, cognitive ability, muscle mass retention in both young and old men, etc. Testosterone is one of the most important hormones for both men and women, and low levels for both sexes are detrimental to a high quality of life. The current data on testosterone and prostate cancer shows that higher levels of testosterone don’t contribute to prostate cancer. Testosterone, then, also isn’t a cause for the racial gap in prostate cancer because other environmental factors better explain it. If people really are happy about having lower testosterone, then I hope they have fun living a life with a low sex drive, lower cognition in old age, lower muscle mass and a higher chance of stroke and metabolic syndrome.

One of the most interesting things about testosterone is the possibility that it explains why civilizations rise and fall. There is anecdotal evidence from Rushton, as well as his theorizing that the higher classes in Rome didn’t breed which led to their downfall. We now know that lower fertility rates for men are associated with lower testosterone, so along with Barzilai’s thesis of testosterone causing the rise and fall of civilizations, Rushton’s theorizing of the cause of lower European fertility and the cause of the fall of the Graeco-Roman empire.

Testosterone is an extremely important hormone, one that drives human evolution and society formation since it’s associated with dominance and confidence. Low testosterone is looked at as ‘good’ because those with higher intelligence have lower levels of the hormone (indicated by lower confidence and having sex at a later age). I showed that the higher IQ East Asian men have a problem finding dates and being looked at as sexually attractive (even though they rated themselves as average). Along with lower East Asian fertility, specifically in Japan, does it seem to you like the high IQ people are more desired if they are having problems keeping their birthrates up? The fact of the matter is, lower levels of testosterone are correlated with lower levels of fertility. If men don’t have as much testosterone pumping through their veins, they will be less likely to have sex and thusly reproduce.

References

Batrinos, M. L. (2012). Testosterone and aggressive behavior in man. International Journal of Endocrinology & Metabolism,10(3), 563-568. doi:10.5812/ijem.3661

Bernhardt, P. C., Jr, J. M., Fielden, J. A., & Lutter, C. D. (1998). Testosterone changes during vicarious experiences of winning and losing among fans at sporting events. Physiology & Behavior,65(1), 59-62. doi:10.1016/s0031-9384(98)00147-4

Carcaillon, L., Brailly-Tabard, S., Ancelin, M., Tzourio, C., Foubert-Samier, A., Dartigues, J., . . . Scarabin, P. (2014). Low testosterone and the risk of dementia in elderly men: Impact of age and education. Alzheimer’s & Dementia,10(5). doi:10.1016/j.jalz.2013.06.006

Ciocca G, Limoncin E, Gravina GL, et al. Is testosterone a food for brain? Sex Med Rev 2016;4:15-25.

Daka, B., Langer, R. D., Larsson, C. A., Rosén, T., Jansson, P. A., Råstam, L., & Lindblad, U. (2015). Low concentrations of serum testosterone predict acute myocardial infarction in men with type 2 diabetes mellitus. BMC Endocrine Disorders,15(1). doi:10.1186/s12902-015-0034-1

ESHRE Capri Workshop Group. Europe the continent with the lowest fertilityHum Reprod Update 2010; 16: 590–602.

Eisenegger, C., Kumsta, R., Naef, M., Gromoll, J., & Heinrichs, M. (2016). Testosterone and androgen receptor gene polymorphism are associated with confidence and competitiveness in men. Hormones and Behavior. doi:10.1016/j.yhbeh.2016.09.011

Gapstur SM, Gann PH, Kopp P, Colangelo L, Longcope C, Liu K. Serum androgen concentrations in young men: a longitudinal analysis of associations with age, obesity, and race—the CARDIA male hormone study. Cancer Epidemiol Biomarkers Prev 2002; 11: 10417

Grossmann, M., Thomas, M. C., Panagiotopoulos, S., Sharpe, K., Macisaac, R. J., Clarke, S., . . . Jerums, G. (2008). Low Testosterone Levels Are Common and Associated with Insulin Resistance in Men with Diabetes. The Journal of Clinical Endocrinology & Metabolism,93(5), 1834-1840. doi:10.1210/jc.2007-2177

Howard JM (2001): Androgens in human evolution. A new explanation of human evolution.

Lassek, W. D., & Gaulin, S. J. (2011). Sex Differences in the Relationship of Dietary Fatty Acids to Cognitive Measures in American Children. Frontiers in Evolutionary Neuroscience,3. doi:10.3389/fnevo.2011.00005

Michaud, J. E., Billups, K. L., & Partin, A. W. (2015). Testosterone and prostate cancer: an evidence-based review of pathogenesis and oncologic risk. Therapeutic Advances in Urology,7(6), 378-387. doi:10.1177/1756287215597633

Moffat, S. D., Zonderman, A. B., Metter, E. J., Blackman, M. R., Harman, S. M., & Resnick, S. M. (2002). Longitudinal Assessment of Serum Free Testosterone Concentration Predicts Memory Performance and Cognitive Status in Elderly Men. The Journal of Clinical Endocrinology & Metabolism,87(11), 5001-5007. doi:10.1210/jc.2002-020419

Nyante, S. J., Graubard, B. I., Li, Y., Mcquillan, G. M., Platz, E. A., Rohrmann, S., . . . Mcglynn, K. A. (2011). Trends in sex hormone concentrations in US males: 1988-1991 to 1999-2004. International Journal of Andrology,35(3), 456-466. doi:10.1111/j.1365-2605.2011.01230.x

Ohlsson C, Barrett-Connor E, Bhasin S, et al. High serum testosterone is associated with reduced risk of cardiovascular events in elderly men: the MrOS (Osteoporotic Fractures in Men) study in Sweden. J Am Coll Cardiol. 2011; 58(16):1674-1681.

Park, J., Cho, S. Y., Jeong, S., Lee, S. B., Son, H., & Jeong, H. (2015). Low testosterone level is an independent risk factor for high-grade prostate cancer detection at biopsy. BJU International,118(2), 230-235. doi:10.1111/bju.13206

Perheentupa, A., Makinen, J., Laatikainen, T., Vierula, M., Skakkebaek, N. E., Andersson, A., & Toppari, J. (2012). A cohort effect on serum testosterone levels in Finnish men. European Journal of Endocrinology,168(2), 227-233. doi:10.1530/eje-12-0288

Pettaway CA. Racial differences in the androgen/androgen receptor pathway in prostate cancer. J Natl Med Assoc 1999, 91: 653:650

Raper, N. R., Cronin, F. J., & Exler, J. (1992). Omega-3 fatty acid content of the US food supply. Journal of the American College of Nutrition,11(3), 304-308. doi:10.1080/07315724.1992.10718231

Richard, A., Rohrmann, S., Zhang, L., Eichholzer, M., Basaria, S., Selvin, E., . . . Platz, E. A. (2014). Racial variation in sex steroid hormone concentration in black and white men: a meta-analysis. Andrology,2(3), 428-435. doi:10.1111/j.2047-2927.2014.00206.x

Rivas AM, Mulkey Z, Lado-Abeal J, Yarbrough S. Diagnosing and managing low serum testosteroneProc (Bayl Univ Med Cent) 2014;27:321-324

Rohrmann, S., Nelson, W. G., Rifai, N., Brown, T. R., Dobs, A., Kanarek, N., . . . Platz, E. A. (2007). Serum Estrogen, But Not Testosterone, Levels Differ between Black and White Men in a Nationally Representative Sample of Americans. The Journal of Clinical Endocrinology & Metabolism,92(7), 2519-2525. doi:10.1210/jc.2007-0028

Ross R, Bernstein L, Judd H, Hanisch R, Pike M, Henderson B. Serum testosterone levels in healthy young black and white men. J Natl Cancer Inst. 1986 Jan;76(1):45–48

Rushton, J. P. (1986). Gene-Culture Coevolution and Genetic Similarity Theory: Implications for Ideology, Ethnic Nepotism, and Geopolitics. Politics and the Life Sciences,4(02), 144-148. doi:10.1017/s0730938400004706

Rushton J P (1997). Race, Evolution, and Behavior. A Life History Perspective (Transaction, New Brunswick, London).

Safarinejad, M. R., Hosseini, S. Y., Dadkhah, F., & Asgari, M. A. (2010). Relationship of omega-3 and omega-6 fatty acids with semen characteristics, and anti-oxidant status of seminal plasma: A comparison between fertile and infertile men. Clinical Nutrition,29(1), 100-105. doi:10.1016/j.clnu.2009.07.008

Sharpe, R. M. (2012). Sperm counts and fertility in men: a rocky road ahead. EMBO reports,13(5), 398-403. doi:10.1038/embor.2012.50

Stattin, P., Lumme, S., Tenkanen, L., Alfthan, H., Jellum, E., Hallmans, G., . . . Hakama, M. (2003). High levels of circulating testosterone are not associated with increased prostate cancer risk: A pooled prospective study. International Journal of Cancer,108(3), 418-424. doi:10.1002/ijc.11572

Travison, T. G., Araujo, A. B., O’Donnell, A. B., Kupelian, V., & Mckinlay, J. B. (2007). A Population-Level Decline in Serum Testosterone Levels in American Men. The Journal of Clinical Endocrinology & Metabolism,92(1), 196-202. doi:10.1210/jc.2006-1375

Tsujimura, A., Miyagawa, Y., Takezawa, K., Okuda, H., Fukuhara, S., Kiuchi, H., . . . Nonomura, N. (2013). Is Low Testosterone Concentration a Risk Factor for Metabolic Syndrome in Healthy Middle-aged Men? Urology,82(4), 814-819. doi:10.1016/j.urology.2013.06.023

Yeap, B. B., Hyde, Z., Almeida, O. P., Norman, P. E., Chubb, S. A., Jamrozik, K., . . . Hankey, G. J. (2009). Lower Testosterone Levels Predict Incident Stroke and Transient Ischemic Attack in Older Men. Endocrine Reviews,30(4), 411-411. doi:10.1210/edrv.30.4.9994

Yuki, A., Otsuka, R., Kozakai, R., Kitamura, I., Okura, T., Ando, F., & Shimokata, H. (2013). Relationship between Low Free Testosterone Levels and Loss of Muscle Mass. Scientific Reports,3. doi:10.1038/srep01818

Are There Race Differences in Penis Size? Part II

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I haven’t completely discredited the notion that Rushton and Lynn may be correct on this variable, but I’m highly skeptical. Hormonal data doesn’t show it. Hormones like IGF-1 and androgen don’t show the differences between races that would lead you to believe that Rushton’s Rule applies here.

PP is at it again, citing the same studies, not providing primary sources, and not addressing what I say to him about hormones in regards to penis size. Hormones affect the body in different ways, and different races have different levels of hormones. This is what I will discuss today.

Insulin-like growth factor 1 (IGF-1) is a hormone that, as it’s name implies, is structurally similar to the hormone insulin. IGF-1 is “partly responsible for systemic GH activities although it possesses a wide number of own properties (anabolic, antioxidant, anti-inflammatory and cytoprotective actions).” Laron and Klinger (1998) showed that children with Laron syndrome who stopped receiving IGF-1 injections showed reductions in penile and testicular size and they returned to pretreatment serum levels. This shows the effects of IGF-1 on sexual organ size.

Knowing this about IGF-1, for Rushton’s theory to be plausible, Blacks would have higher levels, Asians the lowest, and whites in the middle, skewing towards Asians. Platz et al (1999) investigated whether there were racial differences in circulating IGF-1 and insulin-like growth factor-binding protein 3 (IGFBP-3). IGFBP-3 binds IGF-1 and 2, with a dysregulation of IGFBP-3 correlating with cancer. IGFBP-3 is the main transporter of IGF-1 and 2 in the blood stream. The researchers tested men whose self-described ancestry (we know that self-describer ancestry is a great proxy for race, having a 99.86 percent success rate) African American (63) a random sample of Asians and Caucasians (75 respectively) aged 45 to 78 years old. Caucasians had the highest levels of IGF-1 (224 ng/ml), Asians (208 ng/ml), and African Americans (205 ng/ml). The IGF-1:IGFBP-3 ratio was greatest in Caucasians and lowest in Asians. This study was carried out to see if IGF-1 had an effect on prostate cancer. The 13 percent difference in IGFBP-3 between blacks and whites may account for the higher levels of prostate cancer, as IGFBP-3 can control IGF-1 bioavailabilty.

PP also cites Ross et al (1986) showing that blacks have “19 percent higher testosterone”, attempting to use this as evidence for the theory in favor of an inverse relationship between brain size and penis size. He seems to think that total testosterone matters, when what matters is free testosterone.It’s also 15 percent circulating testosterone, 13 percent free testosterone in that one study.  Free testosterone is biologically active, and is able to exert its effect by passing through a cell and activating its receptor. Speaking of free testosterone, in this meta-analysis of 23 studies on black-white differences in testosterone, Richard et al (2014) showed a 2.5 to 4.9 percent difference in free testosterone and concluded that that difference was not enough to account for the racial disparity in prostate cancer. So it’s either black Americans have lower levels of IGFBP-3 or diet/environmental factors that cause this racial disparity in prostate cancer, not testosterone.

Rohrmann et al (2007) showed that testosterone differences between blacks (n=363) and whites (n=674) did not noticeably differ (5.29 ng/ml and 5.11 ng/ml respectively). Mexican Americans (n=376) , on the other hand, showed a higher average rate (5.48 ng/ml) over both cohorts. Blacks had higher levels of estradiol than whites (40.80 pg/nl and 35.46 pg/nl respectively). Blacks also had a higher level of sex hormone-binding globulin (SHGB) (36.49 nmol/liter) than whites (34.91 nmol/liter) and Mexican Americans (34.91 nmol/liter). That may account for some of the racial disparity in prostate cancer, but it’s not testosterone (which shows that ‘higher levels of testosterone’ as PP says, isn’t proof of any racial differences in penis size).

The Kinsey data is nonrepresentative and nonrandom. We have comparative sizes for certain ethnies, and the only statistical difference is between Nigerians and Koreans and Czechs. Rushton and Boegart didn’t mention that blacks danced less than white college students, blacks are more prudish regarding nudity, more likely to have a prostitute as a sexual partner and less likely to want large families (Weizmann et al, 1990). A study on certain CAG repeats shows that Africans cluster with East Asians on two measures, contradicting Lynn’s hypothesis. French Army Surgeon, lol (see Weizman et al 1990 from above):

This work is filled with internal contradictions. For example, an average African Negro penis is said to be 7 3/4 to 8 inches long on p. 56, while on p. 242 it is stated that it “generally exceeds” 9 inches. Similarly, while the French Army surgeon announces on p. 56 that he once discovered a 12-inch penis, an organ of that size becomes “far from rare” on p. 243. As one might presume from such a work, there is no indication of the statistical procedures used to compute averages, what terms such as “often” mean, how subjects were selected, how measurements were made, what the sample sizes were, etc.

I think I’ve shown that there are no “””racial””” differences in size with the Veale et al 2014 study and the Orakwe and Ebuh (2007) study. As far as I see, two statistical differences exist between Nigerians and Koreans and Czechs. But there’s not enough “””quality data””” to say “this race bigger than that race”. To believe there are racial differences in penis size or that there is even an inverse relationship between penis size and brain size takes a huge leap of faith to believe.

There are, without a doubt, average differences in a lot of things between races; hormones being one of them. Any differences  between races in IGF-1 have no effect on penis size (IGF-1 is, however, one reason why black girls reach menarche at a younger age than white girls. Will write more on that in the future.). Africans were more similar to Asians that Caucasians on two of the five androgen indicators that Dutton (2015) tested. The Kinsey data is nonrepresentative and nonrandom and that is what PP continuously references. I’m highly skeptical leading towards no based on my knowledge of hormones and how they work in the human body. Testosterone does not explain any racial differences in penis size, and does not explain any differences in prostate cancer acquisition (though, other hormones do).