Man has reached the evolutionary limit
Homo sapiens has squeezed the maximum possible out of its nature, but there is still room to grow
Andrey Vaganov, Nezavisimaya Gazeta
One of the most weighty "pebbles" in the garden of Charles Darwin's theory of natural selection is the question of whether human evolution continues? And if it continues – where (to what) will she bring the species of Homo sapiens, Homo sapiens? Jean-Francois Toussaint, a professor of medicine at Paris Descartes University, declares that he has managed – no more, no less – to bring final and irrevocable clarity in the literal sense of the word in this matter.
The bar is at a height of 180 centimeters
A medical and sociological study by a French scientist, covering data over the past 120 years, showed that humanity has squeezed the maximum possible out of its nature. The results of this work were published at the end of last year in the journal Frontiers in Physiology.
Life expectancy, average height and physical abilities were taken into account. Genetic factors and the external environment were also taken into account. "These indicators are no longer growing, despite continued progress in nutrition, medicine and science. So, modern society has already allowed the species (Homo sapiens. – "NG-science") to reach their own borders. We are the first generation to realize this," Professor Toussaint's article emphasizes. And as an empirical proof, for example, such data are given.
Despite the tremendous progress of medical science and public health, the maximum recorded human life expectancy has not exceeded about 120 years. The average height since the 1980s has remained at about 170 centimeters for women and 180 centimeters for men. An indirect, but such a clear indicator as the speed of updating sports records has fallen sharply. Every new fraction of a second, centimeters and grams are given with incredible difficulty, the maximum indicators almost do not grow.
The human species has reached the plateau stage, Toussaint concludes. Only the number of people reaching the maximum indicators for the Homo sapiens species is growing. Although not everyone will be lucky enough to do this. Environmental changes, including climatic ones, can provoke a rollback in terms of human size and life expectancy. Thus, in a number of African countries over the past 10 years, the average growth of residents has decreased. This means that some communities can no longer provide adequate nutrition to all children, maintain healthy living conditions for them.
And you really can't argue with that. Five years ago, research by English and Australian scientists, the results of which were published in the Oxford Economic Papers journal, showed that modern European men are on average more than 10 cm taller than their ancestors who inhabited the continent only a little more than a hundred years ago. Today, the average height of a 21-year-old European is 1.79 m. In addition, it was possible to find out the dynamics of anthropometric indicators for individual nations. Thus, the average height of British men aged 21 increased from 167 to 177 cm.
Secular changes
(From lat. saeculum – "genus, generation; century, century" – VM).
It should be noted that the study of British scientists and their Australian colleagues was based on data on the anthropometric parameters of men from 15 European countries. The scientists were helped by medical and military archives. By the way, the absence of such databases regarding women did not allow researchers to determine the dynamics of changes in the growth of European women.
Like the current conclusions of the French, the authors of the article in the Oxford Economic Papers stated that the increase in the body length of the male European population was facilitated by an overall increase in well-being, improved housing conditions and an increase in the average level of education of the inhabitants of the continent. But something else is important here…
Socio-economic factors are the main thing in secular changes (that is, in the processes of epochal, intergenerational, and not individual development). In countries where there is a high level of social inequality, population growth decreases. "Growth is a mirror of the processes taking place in society," emphasizes Marina Butovskaya, a well–known Russian anthropologist, Doctor of Historical Sciences.
Surprisingly different: this epochal increase or decrease in body size in the history of mankind goes in waves. What is the cause and what is the consequence – it can be difficult to track. So, in the XVII–XIX centuries, there was a drop in body size in Europe. And just during this period, for example, the Great French Revolution, the Napoleonic Wars are taking place! However, everything is fixable: during the XIX–XX centuries, the growth of conscripts in European armies is increasing: the inhabitants of the Pyrenees have grown by an average of 3-5 cm, and the Netherlands gives as much as 15 cm!
There are attempts to track the dynamics of secular changes in the growth of our compatriots. "Compared with the 1920s and 30s, one-year-old children of the 1970s had a body length of 4-5 cm, and a weight of 1.2–1.5 kg more than their peers in previous generations," the authors of the Demographic Encyclopedia note (editor-in-chief A.A. Tkachenko, M., 2013). – During the 1940s and 80s, in the most developed countries, the body length of adolescents aged 13-15 years increased by an average of 2.7 cm, and body weight - by 2.3 kg for each decade. This process was particularly intense from the late 1950s to the 1970s." But... "in the 1980s, data were obtained indicating the cessation of acceleration in urban, in particular, Moscow children."
So, the evolutionary development of man as a species is complete. Point. But…
Goodbye, Y chromosome
"This material requires a lot of time to study and think through," one of the authoritative Russian anthropologists stressed in response to a request from NG–nauka to comment. – But the material is certainly interesting. And polemical. It makes sense to gather round tables, arrange TV debates on this issue, attract attention." A completely understandable and reasonable position of a responsible professional, a specialist. Moreover, the empirical material on this topic is huge, continues to accumulate rapidly and is often contradictory.
In 2004, at the 15th International Conference on Chromosome Problems, held in London at Brunel University, Professor Jenny Graves from the Australian National University argued that in the next 10 million years, men as a biological subspecies ... may be on the verge of extinction. Graves bases his evolutionary pessimism on the hypothesis he put forward: the mammalian Y chromosome will eventually lose its several dozen genes, including the SRY gene (the so-called masculinity gene – Sex-determining Region of Y), which is responsible for the production of male hormones and for spermatogenesis.
The Y chromosome originated 300 million years ago, at that time there were 1,438 genes in its composition. Since then, she has already lost 1,393 of them. It should be noted that the numerical characteristics of the Y chromosome operated by Graves are constantly being refined in the process of studying the human genome. Thus, Professor Vyacheslav Tarantul, Head of the Department of Viral and Cellular Molecular Genetics at the Institute of Molecular Genetics of the Russian Academy of Sciences, in the monograph "The human Genome: an encyclopedia written in four letters" (M., 2003), gives the minimum estimated number of genes in the Y chromosome - 82.
The new thing that Australian Jenny Graves added to the picture of the evolution of the male Y chromosome is, in essence, the following important point: during a study on rodents lacking the SRY male gene, it was found that another chromosome took on the task of providing "shelter" to the gene that determines the sex of an individual. Graves argues that if the same thing happens to people, it can lead to the emergence of two or more systems that determine gender, resulting in two (or even more!) different kinds of people.
Of course, all these are just hypotheses, model calculations. But they don't have to be discounted.
Doctor of Medical Sciences, Professor Lev Etingen in the book "Mythological Anatomy" (Moscow, 2006), giving a drawing and description of the skeleton of a man of the future (according to V. Bystrov), warns: "... do not be particularly surprised by anatomical miracles in the form of the absence of not only collarbones, but also ribs in general, a decrease in the number of vertebrae, and in the limbs are missing something of the usual." Meanwhile, "by 1949, 50 cases of missing collarbones in humans had been described. And in such people, it was possible to bring the shoulder joints closer together until they were completely in contact."
It is clear that 50 cases are not evolution yet: a random and rare mutation. And mutations should fit into the context. Usually macromutants die quickly. "Mutations are constantly occurring in humans; there are no special mutational explosions. At the molecular level, mutations accumulate constantly. This is set by the environment. But the genetic apparatus provides for the acceleration of mutations when a person is ill. This is the case with all species," explains Svetlana Borinskaya, Doctor of Biological Sciences, a leading researcher at the Genome Analysis Laboratory of the N.I. Vavilov Institute of General Genetics.
Evolution of the electric species
Nevertheless, evolution seems to be very difficult to stop. If at all possible. In 2011, Alexander Markov, Doctor of Biological Sciences, a leading researcher at the Paleontological Institute of the Russian Academy of Sciences, at one of the public lectures, answered the question of whether evolutionary selection continues: "Now there is some very weak selection for individuals with low cholesterol and an early age of birth of offspring."
Moreover, probably in order to highlight the limiting cases in this problem, some experts deliberately escalate the question: "Is man the pinnacle of evolution?"
A remarkable Russian scientist, Doctor of Biological Sciences Boris Mednikov: "A person looks more like the fetus of an ape than an adult gorilla or chimpanzee. The well–known anthropologist Bolk expressed this somewhat paradoxically: a man is a sexually mature embryo of a monkey. However, not all anthropologists share his view" (B.M. Mednikov. "Axioms of Biology". M., 1982).
Russian anthropologist Stanislav Drobyshevsky, Candidate of Biological Sciences, Associate Professor of the Department of Anthropology of the Faculty of Biology of Lomonosov Moscow State University, gives such arguments.
The volume of the human brain is large, but not extraordinary. Dolphins, whales, elephants have brains 2-3 times larger (in absolute size). In other animals – shrews, hummingbirds, monkeys – the brain is also several times larger than the human brain in terms of relative size. 20-30 thousand years ago, the brain of Homo sapiens was larger: Neanderthals had 1550 cubic meters. cm; for modern men – 1400 cc.
Early Cro-Magnons had a more massive skull. That is, in modern man there is a return to the gracile skull – this is a return to the primitive state. The only progressive finding of evolution is the late fusion of the skull bones, which makes it possible for brain growth.
A big brain is very energy–intensive, and it's still a question of how big a brain is a progressive achievement of evolution. This is connected with the disappearance of vibrissae in humans – even a gene is known, a mutation in which led to the disappearance of vibrissae.
Walking upright led to hair loss. Also another question – is this progress?
The human foot is a highly specialized organ. In this sense, walruses, ostriches have surpassed man. Another couple of tens of millions of years – and you'll see, you'll get something like artiodactyl. The human hand is much more primitive than that of a chimpanzee, for example. In tarsier monkeys, the terminal phalanges of the fingers are much larger than in humans.
And the conclusion that Stanislav Drobyshevsky makes: "There is no peak of evolution as such. Every particular being has the right to consider himself a peak. A person cannot be considered a peak by any of his attributes, except for behavior. But this is not morphology… But evolution is not over now. And a person can already improve himself through external mechanisms and through genetic manipulation."
To add a little oil to the ongoing bonfire of evolutionary disputes, I will give one more quote. "Since we stepped into the hitherto forbidden fields of electricity, gramophones, telephones, aeronautics, astronomy, we have entered a new life that requires extraordinary stability of temperament from a person. We stayed with our ordinary forces, like midgets between Gullivers." ("St. Petersburg Vedomosti", November 6, 1911)
By the way, according to the well–known concept of the Canadian sociologist Marshall McLuhan, all these "hitherto forbidden areas of electricity, gramophones, telephones, aeronautics, astronomy" are nothing but external extensions of man. "Throughout the mechanical epochs, we have been expanding our bodies in space," McLuhan warned in 1964. – Today, when more than a century has passed since the advent of electrical technology, we have expanded our central nervous system to universal proportions and abolished space and time, at least within our planet. We are rapidly approaching the final stage of human expansion outside – the stage of technological simulation of consciousness, when the creative process of cognition will be collectively and corporately expanded to the scale of the entire human society in much the same way as previously, thanks to various means of communication, our feelings and our nerves were expanded outward."
So, maybe now not just a species of Homo sapiens is evolving, but this "expanded" person? The unambiguous answer to this question seems to be limited to one paradox, which was very well formulated by Vladimir Nabokov: "It is a pity that it is impossible to imagine something that has nothing to compare with."
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