A recent study, leveraging on Charles Darwin’s theory of evolution by natural selection, says the human race is still evolving.
The study analysed the genomes of 210,000 people in the US and Britain, showing that the genetic variants linked to Alzheimer’s disease and heavy smoking are less frequent in people with longer life spans, suggesting that natural selection is weeding out these unfavourable variants in both populations.
The researchers at Columbia University also discovered that sets of genetic mutations that predispose people to heart disease, high cholesterol, obesity, and asthma, also appear less often in people who lived longer.
They explained that these genes are therefore more likely to be passed down and spread through the population
According to them, new favourable traits evolve when genetic mutations arise that offer a survival edge.
As the survivors of each generation pass on those beneficial mutations, the mutations and their adaptive traits become more common in the general population.
They also found that those genetically predisposed to delayed puberty and child-bearing lived longer.
They said a one-year puberty delay lowered the death rate by 3 to 4 percent in both men and women; a one-year childbearing delay lowered the death rate by 6 percent in women.
But they caution that environment plays a role, and as such, traits that are desirable now may not be in other populations or in the future.
“The environment is constantly changing,” said Hakhamenesh Mostafavi, the study’s lead author.
“A trait associated with a longer lifespan in one population today may no longer be helpful several generations from now or even in other modern day populations.”
On his part, Joseph Pickrell the study co-author said: “It’s a subtle signal, but we find genetic evidence that natural selection is happening in modern human populations.”
The study was published on September 5 in PLOS Biology.
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