Topic ID #14176 - posted 10/3/2011 6:35 PM

Recent Human Evolution Detected in Quebec Town History



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Recent Human Evolution Detected in Quebec Town History

    By Brandon Keim Email Author
    October 3, 2011  |
    4:37 pm  |
    Categories: Anthropology, Biology, Genetics

Though ongoing human evolution is difficult to see, researchers believe they’ve found signs of rapid genetic changes among the recent residents of a small Canadian town.

Between 1800 and 1940, mothers in Ile aux Coudres, Quebec gave birth at steadily younger ages, with the average age of first maternity dropping from 26 to 22. Increased fertility, and thus larger families, could have been especially useful in the rural settlement’s early history.

According to University of Quebec geneticist Emmanuel Milot and colleagues, other possible explanations, such as changing cultural or environmental influences, don’t fit. The changes appear to reflect biological evolution.

“It is often claimed that modern humans have stopped evolving because cultural and technological advancements have annihilated natural selection,” wrote Milot’s team in their Oct. 3 Proceedings of the National Academy of Sciences paper. “Our study supports the idea that humans are still evolving. It also demonstrates that microevolution is detectable over just a few generations.”

'Our study supports the idea that humans are still evolving.'
How humans evolve in modern societies is an enduringly fascinating question. It’s easy to assume that, in an age of developed-world plenty, biological evolutionary pressures have ceased, and biological evolution is supposedly too slow to detect in time scales of a few generations.

In fact, genetic signals of recent human evolution have been found, and there’s even reason to think it’s speeding up. But such genetic signatures, unconnected for now to identifiable traits, are far less glamorous and tangible than fertility.

Milot’s team based their study on detailed birth, marriage and death records kept by the Catholic church in Ile aux Coudres, a small and historically isolated French-Canadian island town in the Gulf of St. Lawrence. It wasn’t just the fact that average first birth age — a proxy for fertility — dropped from 26 to 22 in 140 years that suggested genetic changes. After all, culture or environment might have been wholly responsible, as nutrition and healthcare are for recent, rapid changes in human height. Rather, it was how ages dropped that caught their eye.

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