Saturday, April 13, 2013

Horizon: Neanderthal 

In 1848 a strange skull was discovered on the military outpost of Gibraltar. It was undoubtedly human, but also had some of the heavy features of an ape... distinct brow ridges, and a forward projecting face. Just what was this ancient creature? And when had it lived? As more remains were discovered one thing became clear, this creature had once lived right across Europe. The remains were named Homo neanderthalensis (Neanderthal man) an ancient and primitive form of human.

The archaeological evidence revealed that the earliest Neanderthals had lived in Europe about 200,000 years ago. But then, about 30,000 years ago, they disappeared... just at the time when the first modern humans appear in Europe. The story has it that our ancestors, modern humans, spread out of Africa about 100,000 years ago with better brains and more sophisticated tools. As they spread into Neanderthal territory, they simply out-competed their primitive cousins.

But was Neanderthal really the brutish ape-man of legend, or an effective rival to our own species? And how exactly had he been driven to extinction? What could be found out about this remarkable evolution from the bones themselves? To begin the investigation a skeleton was needed, and no complete Neanderthal had ever been found.

However a reconstruction expert at The American Museum of Natural History in New York realised that it would be possible to create an entire composite skeleton from casts of partial skeletons. Gary Sawyer combined and rebuilt broken parts to create the most complete Neanderthal ever seen. This Neanderthal stood no more than 1.65m (5' 4") tall, but he had a robust and powerful build - perfect for his Ice Age environment. But would he have stood up to the cold better than modern humans?

Cold adaptation
The popular image of the Ice Age is a period of unremitting freezing conditions. But over nearly a million years, Europe has seen huge climate swings including warm as well as cold periods. For much of the last 200,000 years, when Neanderthals were alive, the climate was mild, sometimes even warmer than today's. But they did also have to live through periods of intense cold.

Professor Trenton Holliday is a body plan expert from Tulane University, New Orleans. After seeing the skeleton, he believed it had comparatively short limbs and a deep, wide ribcage. This body plan minimises the body's surface area to retain heat, and keeps vital organs embedded deep within the body to insulate them from the cold.

To see if this would have helped him to survive, anthropology professor Leslie Aiello from UCL, teamed up with Dr George Havenith, who runs a laboratory studying the way modern humans retain heat at Loughborough University. They subjected two modern humans with very different body shapes to cooling in an ice bath. One had the long limbed, athletic shape of a runner, the other had a stockier, heavily-muscled body plan closer to that of a Neanderthal.

The heavily muscled person lasted longer in the ice bath, so it seems that Neanderthal would have had an advantage. His muscle would have acted as an insulator, and his deep chest did help to keep organs warm. Even so, the advantage doesn't mean that Neanderthal could have survived the icy extremes. This was a polar wasteland and his heavily muscled body plan needed a lot of feeding - about twice as much as we need today.


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