Scientists from the United States analyzed the genomes of men and women from the UK and came to the conclusion that sexual dimorphism began to smooth out in our ancestors even before the transition to agriculture.
The work was published in the journal PLOS Genetics. Sexual dimorphism refers to the anatomical differences between males and females of the same species. It can manifest itself in a variety of physical parameters: size, hairline, color, skin structure, and tooth shape.
According to one of the hypotheses, sexual dimorphism is more pronounced, the more different the contribution of both sexes to offspring care is. It can also be an indicator of the level of polygamy. So, men are slightly larger and stronger than women, their hair is partly differently distributed.
In ancient times, sexual dimorphism in ancestors was more pronounced. Some scientists believe that smoothing began to occur due to the transition to agriculture about 10 thousand years ago. However, other experts believe that this happened as a result of random mutations. Researchers from Pennsylvania State University came to a similar conclusion.
They found out whether genetic variation associated with certain physical traits in men and women has become more or less common over the past three thousand years. In particular, the scientists analyzed height, body weight, waist and hip circumference, and body fat percentage. To do this, they used the genomic data of about 194 thousand women and 167 thousand men, taken from the UK Biobank.
The authors of the study found more than 3,000 variations in genes responsible for sexual dimorphism in men and women, but only those associated with higher percentages of fat in women are significantly more prevalent than before. Otherwise, everything remained the same. Thus, scientists suggest that sexual dimorphism became less pronounced before people finally switched to agriculture.