June 5, 2009

THIS BEING DARWINISM, THAT WHICH THE THEORY REQUIRES...:

New Questions About Purpose of Big Brains (Robin Lloyd, 6/04/09, LiveScience)

This "social brain hypothesis" may pertain in some groups, but overall it's false when it comes to the natural history of carnivorous mammals such as cats, dogs, weasels, bears and their relations, two evolutionary biologists now say.

It's true that bigger brains — in such animals as whales, dolphins, primates and birds — are associated with greater behavioral flexibility and adaptability to new environments. But big brains relative to overall body mass (this ratio is referred to as encephalization) also take a lot of energy to maintain. And some brains tend to get smaller when animals are domesticated or are hunted less by other animals. So the overall trend has been hard to discern.

John Finarelli of the University of Michigan and John Flynn of the American Museum of Natural History in New York sought to work out the relationship on a bigger data set that anyone had previously devised — including 289 terrestrial carnivores, about half of which were fossil (extinct) species. They laid data on sociality, body mass and brain size over the evolutionary tree for all carnivores to investigate the relationship between brain size and sociality.

They found the relationship might hold up among living members of the Canidae family (wolves, foxes, coyotes and jackals), but that's about it.


...naturally does not occur.

Posted by Orrin Judd at June 5, 2009 5:02 PM
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