Human evolution

[da]

Conventional wisdom is that human natural selection has dropped off and evolution is slow in modern humans, because there's fewer selective pressures. By analysis of Haplotype Mapping project data, UW-Madison anthropologist John Hawks says that's backwards- we've been evolving 100 times faster over the last 5,000 years than any previous period in human history.


The researchers found evidence of recent selection on approximately 1,800 genes, or 7 percent of all human genes.

[...]

Genetic changes are now being driven by major changes in human culture. One good example is lactase, the gene that helps people digest milk. This gene normally declines and stops activity about the time one becomes a teenager, Hawks says. But northern Europeans developed a variation of the gene that allowed them to drink milk their whole lives — a relatively new adaptation that is directly tied to the advance of domestic farming and use of milk as an agricultural product.

The biggest new pathway for selection relates to disease resistance, Hawks says. As people starting living in much larger groups and settling in one place roughly 10,000 years ago, epidemic diseases such as malaria, smallpox and cholera began to dramatically shift mortality patterns in people. Malaria is one of the clearest examples, Hawks says, given that there are now more than two dozen identified genetic adaptations that relate to malaria resistance, including an entirely new blood type known as the Duffy blood type.

Another recently discovered gene, CCR5, originated about 4,000 years ago and now exists in about 10 percent of the European population. It was discovered recently because it makes people resistant to HIV/AIDS. But its original value might have come from obstructing the pathway for smallpox.



Seen via gmsv_feed.

(And hey! I can follow this article; some of melted_snowball's explanations of what he does for a living may have rubbed off on me after all.)

Comments

[da-lj.livejournal.com]

Heh. The author has a blog with an Infrequently Asked Questions list. They're probably ALL still infrequently asked questions- his paper was just published yesterday. :)

[arcticturtle.livejournal.com]

That's cool. It makes perfect sense to me; the environments we live in have changed much more rapidly in recent millenia than ever before; it stands to reason that the same 'ol same 'ol genome isn't as adaptive as it used to be.

It's a somewhat different set of governing pressures if we manage to remove, say, malnutrition dangers - which is only true for a segment of the populace for a recent period - but it's not like every genome produces precisely the same number of offspring who survive to produce their own offspring. That's what it would take for evolution to "stop", after all.

[http://users.livejournal.com/merle_/]

"Conventional wisdom is that human natural selection has dropped off and evolution is slow in modern humans, because there's fewer selective pressures"

Uhm. It is? I could agree that the dominant emphases are different: I would have little skill in fending off a tiger, but can type faster than just about anyone from a century ago probably could. But "pressures" from within our species would ramp up after we dominated most of the other species.

It is also an odd way (to me) to think of evolution. Evolution is not a pressure, but something that just happens, much like entropy or dust settling on surfaces.