The Times they are a-Changin

by Anne Holden

The evolution of our species’ most famous traits – big brains, walking on two legs, language – took hundreds of thousands of years. But in some cases, evolution doesn’t always take its sweet time.

In a new study published in BMC Evolutionary Biology, an international team of scientists believe they’ve found an example of evolution only a few thousand years in the making.

The research team, led by Andres Moreno of Stanford University, studied FOXI1, a gene involved in water retention in the kidneys. Moreno and his colleagues collected DNA samples from Europeans, East Asians, and the Yoruba, an African tribe living on the southern edge of the Sahara Desert. An analysis of the FOXI1 gene in each group found a considerably different genetic change in the Yoruba, compared to the other groups. This mutation in the Yoruba’s FOXI1 gene may improve tribe members’ ability to retain water, a big advantage if you live near a desert.

The team calculated that the FOXI1 gene mutation evolved between 10,000 and 20,000 years ago, just as the Sahara Desert was drying out from a brief wet spell. As a consequence of an increasingly harsh climate, the ancestors of the modern Yoruba evolved a way to retain water more efficiently than humans in other parts of the world.

This is not the first time scientists have demonstrated unique adaptations in our species’ more recent history. The July 2 issue of the journal Science reported the discovery of a 3,000-year-old genetic mutation that has allowed native Tibetans living at high altitudes to breathe easier than their low-altitude neighbors.

But this FOXI1 gene mutation has wider implications, especially in the light of our changing planet. The last several decades have seen temperatures rise, forests dwindle, and deserts expand, so mutations like the Yoruba’s may eventually help us adapt to the harsh effects of global warming.

As anthropological geneticist Anne Stone of Arizona State University told New Scientist, “Over the long term, if the Earth keeps warming, I would not be surprised to see genetic shifts.” Whether those will take the shape of improved water retention, resistance to disease or changes in body shape, however, remains to be seen.

How do you think humans will evolve over the next 10,000 years? Let us know!

Anne Holden, a docent here at the California Academy of Sciences, is a PhD trained genetic anthropologist and science writer living in San Francisco.

Image by Melvin "Buddy" Baker