[Press release] Did genetic links to modern maladies provide ancient benefits?

From the 28 January 2015 press release at University at Buffalo

study finds that humanity’s early ancestors had genetic variations associated with modern disease, and now the question is why

By Charlotte Hsu

The discovery highlights the importance of balancing selection, a poorly understood evolutionary dance in which dueling forces drive species to retain a diverse set of genetic features.

Credit: From Shaping Humanity, by John Gurche. Image may be republished ONLY in conjunction with stories about the research outlined in this press release.

Caption: A reconstruction ofHomo neanderthalensis, as created by artist John Gurche for the Smithsonian’s National Museum of Natural History. A study led by University at Buffalo biologist Omer Gokcumen compared the DNA of modern humans to Neanderthals and Denisovans (another ancient hominin). The research found that genetic deletions associated with various aspects of human health, including psoriasis and Crohn’s disease, likely originated in a common ancestor of the three species.

BUFFALO, N.Y. — Psoriasis, a chronic skin condition, can cause rashes that itch and sting.

So why would a genetic susceptibility to this and other ailments persist for hundreds of thousands of years, afflicting our ancient ancestors, and us?

That’s the question scientists are asking after discovering that genetic variations associated with some modern maladies are extremely old, predating the evolution of Neanderthals, Denisovans (another ancient hominin) and contemporary humans.

The study was published this month in Molecular Biology and Evolution.

“Our research shows that some genetic features associated with psoriasis, Crohn’s disease and other aspects of human health are ancient,” says senior scientist Omer Gokcumen, PhD, a University at Buffalo assistant professor of biological sciences.

Some of humanity’s early ancestors had the telltale features, called deletions, while others did not, mirroring the variation in modern humans, the scientists found. This genetic diversity may have arisen as far back as a million or more years ago in a common ancestor of humans, Denisovans and Neanderthals.

The discovery highlights the importance of balancing selection, a poorly understood evolutionary dance in which dueling forces drive species to retain a diverse set of genetic features.

The research raises the possibility that the diseases in question — or at least a genetic susceptibility to them — “may have been with us for a long time,” Gokcumen says.

Why this would happen is an open question, but one possibility is that certain traits that made humans susceptible to Crohn’s and psoriasis may also have afforded an evolutionary benefit to our ancient ancesto

– See more at: http://www.buffalo.edu/news/releases/2015/01/034.html#sthash.latn4ejg.dpuf