Are humans still evolving? – The Hindu


Evolution is too slow to detect within a single human lifetime

Evolution is too slow to detect within a single human lifetime
| Photo Credit: Getty Images/iStockphoto

— Anand Songara, Indore

Humans are still evolving — through new mutations, natural selection, migration, and random chance. Modern medicine and technologies have also changed the pressures acting on us.

Put one way, evolution can be discerned from changes in the frequencies of the genetic variants passed down through the generations. But this process is too slow to detect within a single human lifetime.

But one good example of something we know has changed is the ability of human adults to digest milk. Most mammals lose their ability to digest lactose after weaning, but in the last several millennia, genetic variants have allowed this ability to last longer in some human populations.

Another example is our adaptations to high altitudes. Many Tibetans carry variants of the EPAS1 gene that help them cope with low oxygen levels without producing high concentrations of haemoglobin.

In a third example, humans have also evolved through the way they resisted infectious diseases. In regions where malaria is endemic, people with one copy of the sickle-cell variant have some protection against severe malaria.

Overall, evolution has no predetermined direction, so it is hard to predict how humans will change in the coming millennia.

science@thehindu.co.in

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