Why is a person so reasonable
Geneticists have learned how the metabolism of human and Neanderthal brain cells differs
Perhaps this difference explains some of the features of Homo sapiens – for example, a high level of intelligence
Unlike Neanderthals, humans have a mutation in the ADSL gene, which significantly affects the metabolism of purine compounds in brain cells. The results of the study were published by the scientific journal eLife (Stepanova et al., Reduced purine biosynthesis in humans after their divergence from Neanderthals).
"Despite the absence of living Neanderthals, we were able to determine the metabolic characteristics of modern humans and confirm our hypotheses on mouse and cell models," said Vita Stepanova, a graduate student at the Skolkovo Institute of Science and Technology and one of the authors of the study.
The decoding of the genome of Neanderthals, which was carried out by scientists led by Svante Paabo, showed that they left about 2-4% of their genes in human DNA. Scientists believe that some of them helped our ancestors adapt to life in the north. Anthropologists are even more interested in those genes whose structure differs in Neanderthals and Cro-Magnons.
If such differences are found, scientists will be able to determine the cause of the extinction of Neanderthals, as well as learn the characteristic distinctive features of the behavior and anatomy of our ancestors and their neighbors. In particular, a year ago, Paabo and his colleagues discovered that Neanderthals had unusually developed musculature and a reduced pain threshold.
In their new work, Paabo and his colleagues, including Vita Stepanova, discovered another trait that distinguishes Homo neanderthalensis from Homo sapiens. They studied how the metabolism of muscles, kidneys and brains of humans, chimpanzees, macaques and mice differs at the level of individual cells.
The attention of scientists was attracted by differences in the work of the ADSL gene. It has a mutation unique to humans, which geneticists have not found in other primates, rodents and Neanderthals. This part of the genome is responsible for the assembly of the enzyme of the same name, involved in the synthesis of various molecules that contain purine, a nitrogenous compound underlying adenine and guanine, two key "letters" of DNA.
Paabo, Stepanova and their colleagues discovered the A429V mutation in the human version of ADSL. Presumably, it reduced the stability of the enzyme and, accordingly, reduced the concentration of purine compounds in Homo sapiens brain cells. Geneticists have tested whether this is actually the case by inserting a human and Neanderthal version of ADSL into the genome of mice.
Further observations showed that when the human version of ADSL appeared in the genome, rodent neurons actually began to produce significantly fewer purine compounds, whereas the Neanderthal variation of this gene did not affect the metabolism of the mouse brain.
Paabo and his colleagues suggest that this mutation played an important role in the development of unique human abilities, including a high level of intelligence. In favor of this, in particular, says that failures in the metabolism of purines in brain cells often lead to severe intellectual development disorders.
Further experiments on animals and the study of the genomes of modern and ancient people, scientists hope, will give a definitive answer to this question and help to find out exactly how the intellectual abilities of Neanderthals and Cro-Magnons differed.
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