Analysis of the differences in head shape between chimpanzees and other primates showed that human skulls are no different from them in this respect, and that there is no unique relationship between the evolution of different groups of people and the type of their cranium. This is the conclusion reached by scientists who published an article in the journal PNAS.
“We have shown that variations in the shape of the skull of both humans and apes primarily depend on random mutations and variations in the genome, and not on 'directed' natural selection or the need to solve any specific problems. This should be taken into account when analyzing the remains of ancient representatives of the genus Homo,”write Michael Steiper of the City University of New York (USA) and his colleagues.
Back in the 19th century, scientists noticed that the shape and volume of the skull was noticeably different for different individuals and even groups of people, which some unscrupulous individuals tried to use to substantiate various theories of racial superiority. In fact, as hundreds of later studies show, there is no connection between skull shape, cranial volume, and intelligence.
Today, differences in the volume of the skull are of interest to neurophysiologists and geneticists for the reason that features in its structure and size can be associated with or affect the development of various neurodegenerative diseases and specific features of individual development.
Anthropologists, in turn, have long wondered why the skulls of people of different cultures, ethnic groups and races are so different from each other, and why this is not typical of primates and other mammals. These differences are often used to justify theories of racial superiority, linking the shape of the skull and brain volume to the characteristics of the evolution and history of certain groups of people.
Stiper and his colleagues tried to comprehensively examine this issue by comparing how much the skull shape in 12 hominid species, including humans, differs with how high genetic diversity is in their populations. In total, the scientists analyzed nearly four hundred skulls and several thousand DNA samples.
How are they related? If the "scatter" in the shape of skulls and its general outlines are not accidental and were set in the course of long evolution and adaptation to specific environmental conditions, then the number of variations in the genes that determine its anatomy will be noticeably lower than the average for the genome. This is due to the fact that the "correct" shape of the skull will contribute to the survival of its owners.
In reality, the picture was completely different - the number of variations in the genes that control the shape of the skull was approximately equal to the typical level of genetic diversity among all groups of people. A similar picture developed among monkeys - the more "variegated" their populations were, the more varied the shape of their skulls.
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For example, in large populations of chimpanzees living in western Africa, both of these rates were very high, and in a small and isolated group of dwarf gibbons living in the Mentawai Islands, both skulls and genomes of monkeys were very similar to each other.
This at the same time contradicts the incorrect ideas about the “unique” diversity of the shape of the skulls of different ethnic groups and races, and suggests that apes in this respect do not differ from humans. This allows us to use them as an "example" to study the history of the migrations of our direct ancestors from the genus Homo and the evolution of their closest relatives, scientists conclude.