Discovery: Arthritis Could Be The Reason We Survived Ice Age

A New York based study has shown that a genetic mutation in humans which resulted in shortening of bones and perhaps elevated the risk of arthritis, helped them survive ice age. Researchers found that mutation in the gene called GDF5 resulted in short height and reduced the risk of bone fracture from crippling down due to cold weather. This possibly favored the early humans in fighting back the frostbite during ice age. The compact body structure also helped them in migrating from Africa to colder northern climate 10, 000 years ago.

However, in the later period of human evolution, this advantage increased the risk of osteoarthritis which usually occurs after a prime reproductive age, the researchers said. "The variant that decreases height is lowering the activity of GDF5 in the growth plates of the bone."

Another noteworthy finding of this study is that the area that forges this mutant variation is linked to other mutations that affects GDF5 activity in the joints. "This activity increased the risk of osteoarthritis in both knee as well as hip" said Terence Capellini, Associate Professor at the Harvard University. The study, published in the journal Nature, analysed gene GDF5- first linked to skeletal growth in the early 1990s- to understand more about how the DNA sequences surrounding GDF5 might affect the gene's expression.

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The scientists identified a single nucleotide change (while doing the experiment on mice)that is mostly found in Europeans and Asians but rarely occurs in Africans. The laboratory mice revealed that the change decreased the activity of GDF5 in the growth plates of the long bones of the mice used in the experiment. " The potential medical impact of the findings is very interesting because so many people are affected," said David Kingsley, Professor at the Stanford University.

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To shrug off the disadvantages associated with osteoarthritis, the professor added- "This is an incredibly prevalent, and ancient variant. Many people think of osteoarthritis as a kind of wear-and-tear disease, but there's clearly genetic component at work here as well. Now we've shown that positive evolutionary selections has given rise to one of the most common height variants and arthritis risk factors known in human populations."

(With inputs from IANS)