Humans are still evolving—and we can watch it happen

[Judi Lynn]

Humans are still evolving—and we can watch it happen

By Elizabeth Pennisi
May. 17, 2016 , 5:15 PM

Many people think evolution requires thousands or millions of years, but biologists know it can happen fast. Now, thanks to the genomic revolution, researchers can actually track the population-level genetic shifts that mark evolution in action—and they’re doing this in humans. Two studies presented at the Biology of Genomes meeting here last week show how our genomes have changed over centuries or decades, charting how since Roman times the British have evolved to be taller and fairer, and how just in the last generation the effect of a gene that favors cigarette smoking has dwindled in some groups.

“Being able to look at selection in action is exciting,” says Molly Przeworski, an evolutionary biologist at Columbia University. The studies show how the human genome quickly responds to new conditions in subtle but meaningful ways, she says. “It’s a game-changer in terms of understanding evolution.”

Evolutionary biologists have long concentrated on the role of new mutations in generating new traits. But once a new mutation has arisen, it must spread through a population. Every person carries two copies of each gene, but the copies can vary slightly within and between individuals. Mutations in one copy might increase height; those in another copy, or allele, might decrease it. If changing conditions favor, say, tallness, then tall people will have more offspring, and more copies of variants that code for tallness will circulate in the population.

With the help of giant genomic data sets, scientists can now track these evolutionary shifts in allele frequencies over short timescales. Jonathan Pritchard of Stanford University in Palo Alto, California, and his postdoc Yair Field did so by counting unique single-base changes, which are found in every genome. Such rare individual changes, or singletons, are likely recent, because they haven’t had time to spread through the population. Because alleles carry neighboring DNA with them as they circulate, the number of singletons on nearby DNA can be used as a rough molecular clock, indicating how quickly that allele has changed in frequency.

More:
http://www.sciencemag.org/news/2016/05/humans-are-still-evolving-and-we-can-watch-it-happen

[rusty quoin]

1. That is fascinating.

I recall a woman presenting before a group of scientists her theory that the upper palate has evolved in a way that we need braces today. They thought she was shit, but her arguments sounded good to me.

It was about the transformation of the face and how hominids have changed. One thing, I think we are evolving whether or not we feel it.

[Scootaloo]

2. Well of course we are. Every living thing is "still evolving."

Even species that propagate by cloning still occasionally sexually reproduce - except for some rotifers, and they just steal new genetic material from other organisms somehow. So... they're still evolving too, in their weird little zooplanktonic jam-band fashion.

So long as the generations keep rolling on, evolution follows.

[nxylas]

3. Anyone who doubts human evolution should try sitting in a Victorian theatre

We have one in my home town, the Bristol Hippodrome, and the seats there were obviously designed at a time when people were much smaller than they are now.

[eppur_se_muova]

4. That likely reflects nutrtion and general health. nt

[SouthernDemLinda]

6. Growth cannot be chalked up to evolution selecting for taller genes.

Edited From:

www.bbc.com/future/.../20150513-will-humans-keep-getting-taller
BBC

From the 18th Century Revolutionary War through to World War Two in the mid-20th Century, Americans towered above other industrialised folks.

But today, American men typically notch about 176cm and women 163cm – approximately the same height as that of the average 45 years ago, and well behind the modern Dutch.

The average height today in the US is not appreciably different than it was in the mid to late 70s, even the late 60s. About 40 to 50 years of relative plateau.

How have Northern Europeans pulled ahead? Scientists believe that unequal access to nutrition and healthcare in the US compared to more socialised systems in advanced European nations is the difference-maker.

Millions of Americans lack medical insurance and do not see doctors regularly. Pregnant women are afforded little aid in the States, whereas in Holland, "they get home visits from nurses absolutely free.

In addition, a third of Americans are obese, thanks in part to eating too much junk food. Calorie-dense, processed foods can shave centimeters off consumers' growth, owing to developmental and metabolic issues. A Coke, hamburger, diet won't bring us up to the Dutch level.

[eridani]

7. Or try on old Civil War uniforms

Only the freshman boys whose voices haven't changed yet can fit into them.

[Cly]

5. Epically Cool

Thank you for posting this!