Human Evolution In Action

A fascinating discovery of what may be the fastest recorded instance of human evolution ever recorded:

Tibetans live at altitudes of 13,000 feet, breathing air that has 40 percent less oxygen than is available at sea level, yet suffer very little mountain sickness. The reason, according to a team of biologists in China, is human evolution, in what may be the most recent and fastest instance detected so far.

Comparing the genomes of Tibetans and Han Chinese, the majority ethnic group in China, the biologists found that at least 30 genes had undergone evolutionary change in the Tibetans as they adapted to life on the high plateau. Tibetans and Han Chinese split apart as recently as 3,000 years ago, say the biologists, a group at the Beijing Genomics Institute led by Xin Yi and Jian Wang. The report appears in Friday’s issue of Science.

If confirmed, this would be the most recent known example of human evolutionary change. Until now, the most recent such change was the spread of lactose tolerance — the ability to digest milk in adulthood — among northern Europeans about 7,500 years ago. But archaeologists say that the Tibetan plateau was inhabited much earlier than 3,000 years ago and that the geneticists’ date is incorrect.

When lowlanders try to live at high altitudes, their blood thickens as the body tries to counteract the low oxygen levels by churning out more red blood cells. This overproduction of red blood cells leads to chronic mountain sickness and to lesser fertility — Han Chinese living in Tibet have three times the infant mortality of Tibetans.

The Beijing team analyzed the 3 percent of the human genome in which known genes lie in 50 Tibetans from two villages at an altitude of 14,000 feet and in 40 Han Chinese from Beijing, which is 160 feet above sea level. Many genes exist in a population in alternative versions. The biologists found about 30 genes in which a version rare among the Han had become common among the Tibetans. The most striking instance was a version of a gene possessed by 9 percent of Han but 87 percent of Tibetans.

Such an enormous difference indicates that the version typical among Tibetans is being strongly favored by natural selection. In other words, its owners are evidently leaving more children than those with different versions of the gene.

The gene in question is known as hypoxia-inducible factor 2-alpha, or HIF2a, and the Tibetans with the favored version have fewer red blood cells and hence less hemoglobin in their blood.

The finding explains why Tibetans do not get mountain sickness but raises the question of how they compensate for the lack of oxygen if not by making extra red blood cells.

FILED UNDER: Quick Takes, Science & Technology
Doug Mataconis
About Doug Mataconis
Doug holds a B.A. in Political Science from Rutgers University and J.D. from George Mason University School of Law. He joined the staff of OTB in May 2010. Before joining OTB, he wrote at Below The BeltwayThe Liberty Papers, and United Liberty Follow Doug on Twitter | Facebook

Comments

  1. TangoMan says:

    Racism, I’m sure.

  2. Zelsdorf Ragshaft III says:

    You know, Doug, I was just sitting around the other day with some of my peers. We were in deep discussion about why Tibetan do not suffer mountain sickness and Han Chinese do when they try to live in Tibet. One group thought it might be because the Hans do not chew Coca leaves. Then someone spoiled that arguement by saying Tibetans do not either. Then someone suggested maybe they snort powdered cocaine. That idea didn.t go very far. Rumors of coca growing on Everest are exaggerated. That is not why they climb that mountain. Looks to me like you need a real day job if you have time for this nonsense when we have the all time greatest ecological disaster on going and it has taken over 70 days for the Whale to arrive. Why the New Black Panthers can intimidate and a polling place during an election and the DOJ writes it off. I know this evolutionary question boggles the mind of many but don’t you think (?) there might be more important issues to explore? Just askin.

  3. sam says:

    Zelsdorf at the Job Interview

    Interviewer: Well, Mr. Zelsdorf, we’re impressed by your resume. Advanced degree in Silly, years of online buffoonery. But how do you think you would fit in with our Loony Toons cast? We already have our stupid human, Elmer Fudd.

    Zelsdorf: Not knocking Elmer, but I think I can bring it to a whole new level.

    Interviewer: Oh, how so?

    Zelsdorf: For starters, I could play up the Bugs Bunny is gay angle. Elmer’s never done that.

    Interviewer: Bugs Bunny is gay!?

    Zelsdorf: Sure. Look, he’s always eatin’ a carrot, right. Well, there you go.

    Interviewer: Ah, um…

    Zesldorf: And then there’s that Marvin the Martian guy…hell, he’s not martian, he’s black; and that funny headdress–he’s Kenyan. I could run with that.

    Interviewer: I don’t think…

    Zelsdorf: And Daffy Duck…come on, guy’s obviously an Arab Islamical terrorist, Daf’i Duck. Could do a lot with that.

    Interviewer: Mr. Zelsdorf, these ideas are, um, intriguing, but I’m not sure our audience is, ah, ready for them.

    Zelsdorf: Really? Did you see the video of that Michelle Bachman rally? Believe me, those folks are ready.

    Interviewer: Well, I don’t know…

    Zelsdorf: And then there’s Sylvester the Cat.

    Interviewer (warily): What about Sylvester?

    Zelsdorf: He’s homeless, eats out of trashcans. Always looking for a handout. And he’s, whatchamacallit, mulatto. Think of the possiblities there.

    Interviewer: Mulatto?

    Zelsdorf: Yeah, he’s black and white.

    Interviewer: Mr. Zelsdorf…

    Zesdorf: And there’s the whole nazi-communist thing.

    Interviewer: The what?

    Zelsdorf: The nazi-communist thing. You know, all these animals…

    Interviewer (Rising): Gosh, gee, what does the time go? I’m afraid I’ve got another interview scheduled. Thanks for coming in. We’ll be in touch.

    Zelsdorf: I’ve got a lot more ideas.

    Interview. I’m sure you do.

  4. Doug: It was really mean of you to make Zelsdorf read your post. Whaddya do: sit on him and threaten not to get off until he finished it?

  5. Yep, ZR3 is just down right whiny. He isn’t very intellectually curious either.

  6. Neil Hudelson says:

    Any evidence that evolution exists scares the bejeezus out of Zelsman. Evolution means that man as a species betters itself. A human race that betters itself just reminds Zels of his own shortcomings. And it reminds him that his breed–neanderthals–died out quite awhile ago. Who wants to be reminded of a tragic past?

  7. TangoMan says:

    Evolution means that man as a species betters itself.

    I don’t think you know much about evolution at all. Just sayin’.

  8. Neil Hudelson says:

    Know quite a bit, thank you very much. Maybe not the best choice of words, but I was on a train using my blackberry–not exactly in a mood to create the most eloquent rebuttal of Zels’s idiocy.