A large-scale genetic analysis of the DNA of the inhabitants of the UK and the United States shows that the biological evolution of mankind has not stopped and that the number of carriers of "harmful" versions of genes associated with diseases continues to gradually decline under the influence of natural selection, according to an article published in the journal PLOS Biology.
"Traces of this were extremely difficult to find, but we found hints that natural selection continues to work in modern human populations," said Joseph Pickrell, a geneticist at Columbia University in New York, USA.
Today, biologists and evolutionists are actively debating whether human evolution stopped after our ancestors invented tools and moved on to life in large societies of their kind. Some scientists believe that biological evolution has slowed down or even stopped, since the survival of individuals and their likelihood to continue their race began to depend not on the quality of genes, but on intelligence, wealth and social status.
Other evolutionists have questioned this, and over the past two decades, several experiments and studies have been carried out in which biologists have tested how the genome of humanity as a whole has changed over several hundred or thousands of years. These observations often led to conflicting results, which did not add confidence that evolution was continuing.
Pickrell and his colleagues found new evidence that "Darwinian" selection still continues to work among humanity, analyzing the genomes of more than 160 thousand people in the UK and the United States, who recently took part in various genetic studies.
Analyzing their DNA, scientists relied on a simple evolutionary pattern - the longer an individual lives and the better its health, the more it can leave offspring. Accordingly, the more offspring she has, the higher the likelihood that they will pass on their genes to their children and her lineage will continue to exist, and carriers of "bad" versions of genes will die out.
Guided by this idea, scientists compared sets of mutations in the DNA of people from families of centenarians and British and Americans with relatively short or normal life spans, and tried to understand how common "harmful" mutations in their genes. If there are fewer of these mutations in the DNA of centenarians, then this will mean that natural selection continues to work, and the absence of differences in their number will indicate the opposite.
Geneticists managed to find several dozen genes for which such differences were characteristic. This was most noticeable for two regions of DNA - the APOE gene, in which mutations significantly increase the likelihood of developing Alzheimer's disease, and in the CHRNA3 gene, which is associated with a predisposition to active smoking in men.
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"Bad" versions of these genes, as scientists note, were much less common among Americans and Britons who were able to live to 70 years old or whose parents or ancestors were considered centenarians. Many other genes associated with obesity, asthma, atherosclerosis and a number of other health problems, as well as early onset of sexual activity, behaved in a similar way.
In the future, geneticists plan to analyze even larger DNA banks, which will help them find other genes that evolution continues to influence, and understand in which direction humanity is moving today and what is “orchestrating” its development.
