Researchers can now watch human evolution unfold

[eridani]

http://www.economist.com/news/science-and-technology/21698645-researchers-can-now-watch-human-evolution-unfold-not-what-they-were?cid1=cust/ednew/t/bl/n/20160512n/owned/n/n/nwl/n/n/NA/n

To test their method, the researchers turned to 3,195 genomes taken from the UK10K project, which has collected the genetic data of 10,000 Britons. The largest signal they found did indeed come from the allele for lactose tolerance, suggesting that evolution has continued to press the case for milk digestion well into recorded human history. They also found evidence of strong selection for blond hair and blue eyes. This, they speculate, may be a consequence of the sexual preferences of ancient Britons rather than any environmental influence.

Lactose tolerance and hair- and eye-colour are traits strongly influenced by small numbers of genes. But Dr Pritchard’s method can also detect “polygenic” selection, in which the accumulated effects of thousands of small variants conspire to produce a big change in a particular trait. One example is height, which is influenced by the combined actions of thousands of different genes.

Dr Pritchard and his colleagues found that in Britain evolution has, of late, been extremely keen on taller people. Selection for increased height appears to have taken place across nearly the entire human genome. They also found evidence that other ancient evolutionary pressures still operate in comparatively modern populations. Human babies have big heads to contain their outsized brains. Women, in turn, need wide hips to give safe birth to their big-headed offspring. Genetic variations associated with head circumference in infants, and wider hips in women, seem to have become noticeably more common even over the past couple of millennia.

Dr Pritchard’s technique thus adds evolutionary biology to the armoury of archaeological anthropology. His results confirm that modern Britons are subtly but definitely different from those who tried (unsuccessfully) to fight off the Romans. The effects of two thousand years of evolution, covering a hundred or so generations, are such that if ancient Britons were given all the benefits of a modern diet and modern medicine, they would still end up shorter than their modern counterparts, have narrower hips, and give birth to babies with slightly smaller heads.

[Warpy]

1. Lactose tolerance was also a matter of survival for older children in far northern climates

especially in the spring "hunger gap" when dried legumes and hard cheese were just about it until the first cow dropped a calf and her milk came in. If children were becoming lactose intolerant, they'd develop severe diarrhea from dairy products and diarrhea was one of the biggest killers of children of all ages. People who could tolerate lactose had a survival edge over people who couldn't.

As for the blondes, it's probably as much from the influx of Vikings as settlers as it is a preference for blonde hair and blue eyes.

[Xipe Totec]

2. Evolution has, of late, been extremely keen on taller people...