Big Heads, Little Brains

The Times
March 13, 2010




Cro Magnon skull supports theory that human brains have begun to shrink



Humans like to portray themselves as a sophisticated life form driven by brain rather than brawn. So they may be surprised by a project to reconstitute a 28,000-year-old skull from remains found in France.

This has provided evidence to support a theory that our brains have begun to shrink.

[We are shrinking.  And that does not bode well for us, given that we are all intellectual giants I suppose it will not have any effect on us for a very long while!!]

The French team that claims to have produced one of the best replicas yet of an early modern human skull say that it is 15 to 20 per cent bigger than ours. No one suggests that we are 15 to 20 per cent more stupid than Cro Magnon 1, the best preserved of five skeletons discovered in 1868 in the Cro Magnon cave in the Dordogne, because there is only a minor link between brain size and intelligence.

It may be that, rather like computers, our brains are becoming more efficient even as they grow smaller. But the project could shed light on a human evolutionary question that has divided and bemused the specialists: if indeed our heads have started to shrivel, why is this happening?

Cro Magnon 1 has been kept in the French National Museum of Natural History in Paris. He is believed to have been a well-built, elderly man about 6ft tall. Already known to scientists worldwide, Cro Magnon 1 will become even more famous next week when a mold of his skull will be shown at the American National Museum of Natural History in Washington.

The endocast was made by scanning the interior of the skull at the Quinze-Vingts Hospital in Paris to obtain a picture of the impression left by the brain on the neurocranium.

Antoine Balzeau, of the French Museum of Natural History, transformed this into a 3D image that was in turn made into a mold by a specialist software prototyping firm.

“It’s one of the most beautiful endocasts ever,” Mr Balzeau told The Times. He said that an initial assessment of Cro Magnon 1’s skull confirmed the belief that brains had grown "slightly smaller over tens of thousands of years”, reversing an earlier trend towards bigger brains.

However, he said that the cerebellum — a brain structure linked to language and concentration — appears to take up a larger proportion of the head now than in the time of Cro Magnon 1. This suggests that some parts of the brain are more “compressible” than others, he said.

Several theories have been advanced to explain the mystery of the shrinking brain. One is that big heads were necessary to survive Upper Paleolithic life, which involved cold, outdoor activities.

A second theory is that skulls developed to cope with a chewy diet of rabbits, reindeer, foxes and horses. As our food has become easier to eat, so our heads have stopped growing, according to supporters of this theory.

[Small favors.  Imagine.  We could all be walking around with heads like the Queen from Alice!]

Other experts say that with high infant mortality, only the toughest survived — and the toughest tended to have big heads.