The causes of our (imper)fection. Column in ComputerreOnline #38
The hunting method of our ancestors has left an imprint on our bodies. Its traces – both hairlessness, the nature of thermoregulation, and much more. And equally deep traces of this way of life can be found in our psyche.
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Dmytro Shabanov
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Problems of Interpretation Causes of Our (In)Perfection The Trail of the Antelope
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It turns out that I keep reinventing the wheel. Just as I managed to share with readers the enthusiasm caused by the analysis of selective statistics, it turned out that similar, but much deeper analyses were performed and published online. I just wrote a column about our brain as an inadaptation, and by chance, I came across sources that develop the theme of the evolutionary causes of our imperfection. What to do? And I will have to return to the topic of elections, and the limitations of our thinking need to be discussed in more detail, especially since these problems are somehow related. And I will have to start from the beginning: by discussing the lifestyle that shaped our characteristics. How to explain this? I don't know a better example to clarify the peculiarities of our nature than a fragment from Sir David Attenborough's series dedicated to mammals. I always show a "cut" from this film to my students, and I will show it to you too. Some video fragments that I use in my classes, I upload to YouTube; the service regularly sends me notifications that they match materials belonging to other copyright holders. Fortunately, repressive measures do not follow. It seems they really allow the use of video snippets for teaching (and illustrating columns) – thank you for that. Watch.
This is not a complete fragment, but a montage from Attenborough's film. It shows (with some changes) the same lifestyle that shaped our ancestors. Note: where the translator speaks of "buffalo," it should be "bull" – a male kudu antelope. For most of us, urban dwellers, it is difficult to imagine that the runner shown in the film is not a rare exception. Our sedentary lifestyle has led to us being in poor physical shape. Wild mammals seem to us examples of strength, agility, and endurance that exceed human capabilities. However, biomechanically, we are made very successfully. There is no other animal species that can run well, swim well, and climb trees well. In each of these types of physical activity, humans are inferior to "professionals" but outperform them in overall performance. But this is not our main trump card. Humans (in their natural state) are extremely enduring. A trained runner can run a greater distance than a trained mare (such competitions were actually held!), and generally a greater distance than anyone else. The specific hunting method that became available to our species thanks to this feature is shown in Attenborough's film. Yes, our ancestors pursued ungulates not in old sneakers, but barefoot. They carried water not in plastic canisters, but in ostrich eggs or leather bags. Their knives and spears were less technological. However, the hunting techniques remained the same. This hunting method explains two of our amazing features: the weak development of hair cover and a sharp increase in the number of sweat glands. When running across the savanna under a scorching sun, survival depends on the ability to maintain normal thermal balance. A vertical (upright on two limbs) body heats up less from the sun and is better ventilated by the wind than a horizontal (four-limbed) one. Hair on the head protects it from overheating by solar radiation. And from most of the body surface, heat is dissipated through sweat evaporation. Chimpanzees have relatively few sweat glands compared to us. But imagine what would happen if a chimpanzee, like the runner in the shown fragment, ran across the savanna or bushes, sweating profusely? Sweat and dust would form an almost impenetrable armor on its fur, a carapace. What heat dissipation, even if it didn't hinder movement much! That's why the improvement of cooling mechanisms was linked to the reduction of body hair. Human "nakedness," which commentators in one of the recent columns attributed to the aquatic stage of its development, thus finds a perfectly logical explanation. And why does hair remain on the face of men, as well as in the groin and armpits? To demonstrate maturity (beard and mustache) and accumulate scents that characterize individuality. Yes, there is another feature that is mentioned when discussing our supposed aquatic past. The presence of subcutaneous adipose tissue. Other modern hominids (chimpanzees, gorillas, and orangutans) have almost none, while it is well-developed in seals and whales. In both cases, its function is heat conservation, but the logic of this adaptation's development was different. No matter how you look at it, fur warmed our hairy African ancestors. Not in the daytime heat, but during cool nights. Africa is often dry, the local greenhouse effect of the atmosphere is reduced, and nights (even after hot days) can be very refreshing. This is related to the successful solution to thermoregulation found by our species. The thermal insulation layer is moved deeper, under the skin, adapted for shedding excess heat. At night, skin blood supply decreases, and the heat of internal organs is preserved thanks to the subcutaneous fat layer. Does this mean that an aquatic (perhaps more accurately, semi-aquatic) phase in our history did not exist? Not at all. The ease with which people feel in water indirectly suggests that we have evolutionary experience interacting with this environment. But although aquatic and semi-aquatic organisms are well-preserved in the geological record, remains of semi-aquatic hominids have not yet been found. So we still evolved on land. Did all representatives of the ancestral populations of our species run like the hero of the film? Probably not. But the best runners were undoubtedly highly valued, left more offspring, and moreover, their offspring (thanks to their parents' provision) more often survived to adulthood. Now that good runners have no significant reproductive advantage over bad ones, selection for other traits is blurring once-selected adaptations. The transition to a significant proportion of meat in the diet was closely linked to the formation of characteristic features of the genus Homo. It is difficult to draw a line between the last Australopithecines and the first humans (Homo sapiens), and some extinct species are attributed to our genus or to the ancestral genus. But it is clear that a characteristic feature of our genus is a sharp increase in brain size, which requires significant expenditure for its development and functioning. Such an evolutionary acquisition required a serious change in diet, increasing its caloric content and efficiency of assimilation. The size of our brain is a consequence of meat consumption and the transition to consuming thermally processed food. Dietitians and vegetarians have spread the idea that plant-based food is "better" than meat. Yes, it is often healthier for sedentary city dwellers. But plant-based food is digested longer and more complexly and yields much less energy than meat. Meat contains a complete set of essential amino acids and a range of other valuable substances that, in the case of a plant-based diet, must be gathered from many different sources. One practically important consequence follows from the link between meat-eating and brain development. Dear readers! If you experiment with diets or save on food, do it on yourselves or on other adult and healthy people – but not on children. The consequence of a lack of animal protein during key stages of child development can be a reduced intellectual potential. Let's return to the film. It shows us refined adaptations that could not have arisen immediately. Probably, the first method of obtaining meat was scavenging carrion or the remains left by large predators. The savannas where our genus evolved were inhabited by various ungulates (both living and extinct), which were hunted by saber-toothed cats. The huge fangs of saber-toothed cats allowed them to effectively kill thick-skinned large prey and consume large pieces of soft tissue, but did not allow them to clean the skeleton (especially vertebrae, ribs, and skull) of meat residues. Who cleaned the remains? At night – hyenas. During the day – vultures or terrestrial scavengers who could spot vulture activity from afar, quickly run up, and drive away competitors from the carcass remains. Those who did this particularly successfully became our ancestors. They were greatly aided by the technology of using sharp stone fragments to scrape meat off bones and extract bone marrow. The path of their further evolution led from scavenging carcass remains to driving away almost whole bodies from predators that had obtained them, and then to independent hunting, which we saw in the film. This lifestyle of our ancestors is reflected in our bodies. Traces of it are found in our lack of hair, our thermoregulation characteristics, and many features of our biomechanics and physiology. Are you ready to agree with this? And is it harder for you to admit the presence of similar or even more significant traces of this lifestyle in our psyche? Don't rush to deny it. The brain is part of our body. The peculiarities of its structure, determined by the hereditary program of our development, determine which tasks our psyche will solve effectively, and which will prove difficult or inaccessible for it. Both the brain and other parts of the body are the result of selection that occurred under specific conditions. Let's analyze the film fragment from this perspective. What tasks does the runner solve during his hunt? He uses detailed knowledge of the characteristics of animals and plants. Studies of people from traditional cultures show how developed their ability to distinguish and classify species and remember their characteristics is. Do you think the ability to distinguish and classify different species of living organisms is a secondary mental activity, a sphere only for biologists? You are very mistaken. This is one of the basic functions of our thinking, the roots of which go back to the distant pre-root past. Remember what Adam's first task was according to the Book of Genesis? The first thing he did was give names to animals. The idea of classification, an ordered system, is central to modern science. Do you know where it came from in scientific thought? From biology, under the influence of Linnaeus. And Linnaeus relied on the tradition inherited from Aristotle, the creator of the first hierarchical system of animals (and a few other trifles). Well, I won't get sidetracked in this direction... Also, the runner demonstrates the ability to determine who left the animal tracks and where it was going. Do you know that many animals can analyze the smell of tracks, but only humans can read them as hunters and nature experts from traditional cultures do. This is a complex task that requires serious brain development and an innate ability to construct cause-and-effect chains. We do not see the runner's relationships with his fellow tribesmen in the film. By the way, even after the antelope is killed, the runner will still have to work. He (probably with his partners) will have to divide the prey into parts and bring the meat to his tribe's camp. For the runner to be successful, he needs not only to run well but also to be able to negotiate, seek mutually beneficial compromises based on a common understanding of justice. And, characteristically, he even tries to negotiate with the killed antelope! This is also a significant detail in the film. Finally, if we, looking at the runner filmed by Attenborough, imagine that we are looking at one of our distant ancestors, we should not forget that this is one of our male ancestors. There are as many of them in the lineage of each of us as there are female ancestors. What did the runner's wife do while he was hunting? What task solutions influenced the number of her offspring? What abilities did our brain acquire as a result of this selection? Did our male ancestors and female ancestors need the same psyche? How do the consequences of selection that occurred in hunter-gatherer tribes manifest in the psyche of people in the post-industrial era? I cannot present my versions of answers to these questions here – the column is not that large. But do these questions make sense in themselves, without answers?
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Dmytro Shabanov
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Problems of Interpretation Causes of Our (In)Perfection The Trail of the Antelope
Column in KompyuterraOnline #37 Column in KompyuterraOnline #38 Column in KompyuterraOnline #39