We Evolved Low Oxygen Adaptation in Under 3,000 Years

July 4th, 2010 by Susan Kraemer

In encouraging news for species like ours faced with having to figure out how to survive the next centuries of unprecedentedly fast climate change, it appears that at least one evolutionary adaptation developed at breakneck speed.

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Tibetans seem to have evolved their unique ability to breathe at high altitudes in thin air in under three thousand years, UC Berkeley researchers have found.Their comparison of the genomes of 50 Tibetans and 40 Han Chinese in the July 2 issue of the journal Science shows that ethnic Tibetans split off from the Han less than 3,000 years ago and since then rapidly evolved a unique ability to thrive and produce children successfully at high altitudes and low oxygen levels. Without the adaptation, more infants are born dangerously underweight or die at birth at high altitudes.

“This is the fastest genetic change ever observed in humans,” said Rasmus Nielsen, UC Berkeley professor of integrative biology, who led the statistical analysis. “For such a very strong change, a lot of people would have had to die simply due to the fact that they had the wrong version of a gene.”

Usually when people move above 13,000 feet, with 40% lower oxygen levels, they are subject to headaches, exhaustion and altitude sickness. Despite lower oxygen saturation in the blood and lower hemoglobin levels, Tibetans have none of these problems.

After getting informed consent, researchers obtained DNA and took blood samples from 50 Tibetans and 40 Han Chinese from Beijing, who had at least three generations of ancestors at the same site. The Tibetans lived in two villages located at elevations of 14,100 feet and 15,100 feet.

The researchers measured oxygen saturation, red blood cell concentration and hemoglobin content in their blood and compared the genes of the two groups. The variation occurred near a gene called EPAS1, which earlier studies had suggested is involved in regulating hemoglobin in the blood as a response to oxygen levels.

They found that the common ancestors of Tibetans and Han Chinese split into two populations about 2,750 years ago and the larger group moved to the Tibetan plateau. Although the small group that stayed home thrived and expanded, the larger group of migrants to the higher altitudes died back dramatically.

But those few who survived evolved a survival mechanism, that showed up in 87% of the Tibetan migrants, but in only 9% of the Han who had stayed home: lower red blood cell count and lower hemoglobin levels.

Tibetans have been suggested for space missions to Mars because of this ability they have developed to tolerate very thin air. But such fast and resilient adaptation is good news for us even here on Eaarth, which will change beyond recognition due to our fossil-fueled climate change over the next few thousand years.

Image: Flikr user Reurinkjan

Source: eScienceNews

Susan Kraemer @Twitter

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Tags: 3000 years, Adaptation, climate, evolved, Han, hemoglobin levels, high-altitude, oxygen, red blood cell count, Tibetans

About the Author

Susan Kraemer writes at CleanTechnica, CSP-Today, PV-Insider , SmartGridUpdate, and GreenProphet. She has also been published at Ecoseed, NRDC OnEarth, MatterNetwork, Celsius, EnergyNow, and Scientific American. As a former serial entrepreneur in product design, Susan brings an innovator's perspective on inventing a carbon-constrained civilization: If necessity is the mother of invention, solving climate change is the mother of all necessities! As a lover of history and sci-fi, she enjoys chronicling the strange future we are creating in these interesting times. Follow Susan on Twitter @dotcommodity.

Roland Rambau

the research leaves 2 questions open IMHO:

1. how do we know that the common anchestors 3000 years ago were not height adapted – could it have been the Han quickly loosing that adaptation ?

2. it seems that the data only show that many people in Tibet did not procreate – but how do we deduct from this that they died (prematurely I assume, otherwise the comment about lots of people dying would be vain). Couldn’t they have e.g. just moved elsewhere, or just stayed childless ( I seem to remember that Tibet had polyandric family structures which would allow that even when many appear married still only a small percentage of the males sire children etc. ) Could the high speed of adaptation be specifically enabled by polyandrie ?
Dave M.

To say “For such a very strong change, a lot of people would have had to die…” seems a little short sighted. Perhaps the people who tolerated the high altitude simply stayed up there, while the rest went back down. I.E.; instant natural selection.
- http://cleantechnica.com/author/susan Susan Kraemer
  
  Actually, the researchers did also mention neonatal death as one of the ill effects of high altitudes. I left it out as I thought it was confusing. (Who plans a birth on a hike up Everest?) But your comment makes me see why I should have left it in. One of the adaptations mentioned was the ability to bear children at high altitudes. I will include it, thanks for helping put the puzzle together.
LSJ

To adapt to low oxygen, shouldn’t the Tibetans have evolved higher rb cell count and higher hemoglobin levels?
Paul

Susan,

This looks like the kind of story you’re interested in.

http://www.nytimes.com/2010/07/04/business/energy-environment/04solar.html?src=me&ref=business