Paul Manger of Johannesburg's University of the Witwatersrand says the super-sized brains of dolphins, whales and porpoises are a function of being warm-blooded in a cold water environment and not a sign of intelligence. "We equate our big brain with intelligence. Over the years we have looked at these kinds of things and said the dolphins must be intelligent," he said
"The real flaw in this logic is that it suggests all brains are built the same ... When you look at the structure of the dolphin brain you see it is not built for complex information processing," he said in an interview.
A neuroethologist who looks at brain evolution, Manger's views are sure to cause a stir among a public which has long associated dolphins with intelligence, emotion and other human-like qualities.
They are widely regarded as one of the smartest mammals. But Manger, whose peer-reviewed research on the subject has been published in "Biological Reviews of the Cambridge Philosophical Society", says the reality is different. Brains, he says, are made of neurons and glia. The latter create the environment for the neurons to work properly and producing heat is one of glia's functions. "Dolphins have a superabundance of glia and very few neurons ... The dolphin's brain is not made for information processing it is designed to counter the thermal challenges of being a mammal in water," Manger said.
Erica Goode is probably right to suggest, as she did in The New York Times, that trying to compare non-human intelligences to each other isn't an intellectually worthwhile endeavour, that different species have different specializations in different areas. It's just disappointing, and a bit saddening, to realize that cetaceans don't share the specializations most characteristic of human beings.