Why Neanderthals were short-legged

Washington, Oct 23 (ANI): Neanderthals' short legs are thought to be as a result of the cold climate they lived in.

But now researchers at Johns Hopkins have found that lower leg lengths shorter than the typical modern human's let them move more efficiently across the sloped terrain of their mountainous homes.

The findings reveal a broader trend relating shorter lower leg length to mountainous environments that may help explain the limb proportions of many different animals.

"Studies looking at limb length have always concluded that a shorter limb, including in Neandertals, leads to less efficiency of movement, because they had to take more steps to go a given distance," said lead author Ryan Higgins, graduate student in the Johns Hopkins Center of Functional Anatomy and Evolution.

"But the other studies only looked at flat land. Our study suggests that the Neandertals' steps were not less efficient than modern humans in the sloped, mountainous environment where they lived."

Neandertals, who lived from 40,000 to 200,000 years ago in Europe and Western Asia, mostly during very cold periods, had a smaller stature and shorter lower leg lengths than modern humans. Because mammals in cold areas tend to be more compact, with a smaller surface area, scientists have normally concluded that it was the region's temperature that led to their truncated limbs compared to those of modern humans, who lived in a warmer environment overall.

However, Higgins' group adds a twist to this story. Using a mathematical model relating leg proportions to angle of ascent on hills, he has calculated that Neandertals on a sloped terrain would have held an advantage while moving compared to their long-legged cousins, the modern humans.

Because the area Neandertals inhabited was more mountainous than where modern humans tended to live, the researchers say that this assessment paints a more accurate picture of the Neandertals' efficiency of movement as compared to humans.

"Their short lower leg lengths actually made the Neandertals more adept at walking on hills," explains Higgins.

The study has been published online in the American Journal of Physical Anthropology. (ANI)