06 February 2008

Human evolution continues: new evidence

A group of French and Spanish scientists led by population geneticist Luis Quintana-Murci (Lluis Quintana-Murci) has discovered new evidence in favor of continuing human evolution.

Scientists analyzed the DNA of 120 people from the HapMap database, which contains common genetic variations of people, many of which are associated with various diseases, and identified genes that have changed differently in different groups of people over the past 60 thousand years, which is a very short time for evolution. The work of scientists (Natural selection has driven population differentiation in modern humans) was published in the journal Nature Genetics 03.02.2008.

Scientists analyzed the distribution of mutations in various human populations, called single nucleotide polymorphisms – snips, SNP (from the English single nucleotide polymorphism). In different populations of people, substitutions of different nucleotides can occur in the same part of the genome. Often, various replacement options are associated with certain characteristics of a person, for example, with certain hereditary diseases.

In total, scientists analyzed 2.8 million SNPs. Then they selected 15259 non-synonymous mutations that change the amino acid encoded by the nucleotide triplet, and, accordingly, the properties of the protein.

Scientists have found that certain mutations occur in human populations more often than others. They suggested that these mutations enhance human adaptability to environmental conditions. People carrying such mutations are more likely to leave offspring. Accordingly, positive mutations persist in the population.

Interestingly, in different populations of people, different SNPs have become predominant, that is, in a certain place of the genome, most members of this population have the same nucleotide replacement. This observation contradicts the generally accepted opinion that many differences between populations appeared by chance.

In total, scientists found 582 genes that carried different mutations in representatives of different populations. The functions of most of them are still unknown, and about 50 of these genes are associated with certain diseases or regulate metabolism. So, part of the genes is responsible for the production of insulin, the breakdown of sugars and starch, the transport of fats, the breakdown of alcohol, immune reactions, and so on. Mutations in the genes responsible for metabolism, scientists associate with different types of traditional nutrition in different populations.

Source: Team Uncovers New Evidence of Recent Human Evolution (Science News, 02/04/2008).

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