Researchers at Columbia University have analyzed the genomes of 210,000 people in the United States and Britain and come up with the conclusion that people with longer lifespans have less genetic variants linked to Alzheimer’s disease and heavy smoking In other words, the natural selection is weeding out these unfavorable variants in both populations. These researchers also found that the sets of genetic mutations which cause heart diseases among people as well as high cholesterol, asthma, and obesity are less in people who have lived longer and these genes are more likely to be passed down and spread through the population.
The genetic evidence that natural selection is happening in modern human population is great news. New and favorable traits evolve when genetic mutations arise, offering a survival edge. The mutations and their adaptive traits become more common among the people as the survivors of each generation pass on the beneficial mutations. The genomic revolution has enabled biologists to see the natural selection process by making the genetic blueprint of thousands of people and then make a comparison. Tracking the relative fall and rise of mutations across generations have helped researchers to conclude which traits are dwindling and which are spreading.
The researchers found only two common mutation across the whole human genome that are influencing survival, suggesting that selection has purged similar variants from the population. Researchers also found that those people who are genetically predisposed to delayed puberty and child bearing lived longer! A year’s delay in puberty lowered the death rate by 3 to 4% in both the sexes!