Evolution works on all animals, and since humans are animals, we too are subject to the laws of natural selection. These changes are being recorded in our DNA, and scientists have just found a whole host of new adaptations written in our genes.
Natural selection has been working on genes associated with fertility – specifically the age at which women start the menopause – as well as traits that are associated with cardiovascular function. These are the findings reported by researchers in a new study published this week in Nature Genetics.
Humans farming cattle in Europe (and in isolated pockets of India and Africa) evolving to be able to drink milk into adulthood, or how the Sherpa living on the Tibetan Plateau have adapted to the thin air they breathe, are well-known examples, but there are other more subtle changes that are occurring in our genes.
Because evolution happens slowly over thousands of years, we don’t tend to notice it. This is where Professor Jian Yang and his team from the University of Queensland come in. They have developed a statistical method to study the impact that natural selection has had on human DNA.
The researchers looked at the genomic data of 126,545 people, who are part of the UK Biobank project. Form this they homed in on just 28 individual traits, including male pattern baldness, Type 2 diabetes, age at menopause, body fat percentage, heel bone mineral density, and even educational attainment. They then looked at how the genes associated with these traits were changing from generation to generation.
“In natural selection, or ‘survival of the fittest’, characteristics that improve survival are more likely to be passed on to the next generation,” Professor Yang said in a statement. “The opposite also occurs, when DNA mutations with a detrimental effect on fitness are less likely to be passed on, by a process called negative selection.”
Evolution, it would seem, is still working its magic on people even today. The team found good evidence that certain traits even today are being selected against. “Among the strongest associations was with traits related to cardiovascular function, such as waist-to-hip ratio, with excess fat around the waist thought to increase the risk of heart disease and type 2 diabetes,” explained Professor Yang.
But that wasn’t all they found. It also turns out that there is a strong selection among genes related to fertility and the menopause, most likely because there is a strong association between these traits and genetic fitness.
So it seems that even though as a species we are more mobile than ever, have advanced medical care, and like to think of ourselves as above nature, we’re still subject to her rules.