Natural selection continues to weed out unfavourable traits in humans, which means humankind itself is continuing to evolve, albeit at a very slow rate.
These were the conclusions drawn from a large-scale study of genetic data sampled from 210,000 people from the US and UK.
As published in the Sept. 5 issue of PLOS Biology, scientists from the University of Columbia and the University of Cambridge noted that genetic variants linked to Alzheimer’s disease and heavy smoking are rarer in longer-lived individuals.
Those whom longevity favoured also had fewer occurences of heart disease, high cholesterol, obesity, and asthma.
The conclusions drawn were thus that these individuals’ genes had greater chances of being passed down and thus spread through the general population.
“We find genetic evidence that natural selection is happening in modern human populations,” commented Dr. Joseph Pickrell, an evolutionary geneticist at Columbia and New York Genome Center who helmed the research effort.
New favourable traits evolve when genetic mutations arise that offer an advantage in survival. Members of each generation thereafter pass on those beneficial mutations, whereupon they and their adaptive traits become more common in the general population.
The scientists sampled the genomes of 60,000 individuals of European ancestry genotyped by Kaiser Permanente in California, and 150,000 people in Britain genotyped through the UK Biobank.