Blakemore 'falou e disse': o cérebro humano cresceu por acidente e não através da evolução

segunda-feira, março 29, 2010

Colin Blakemore: how the human brain got bigger by accident and not through evolution

Oxford neurobiologist Colin Blakemore tells Robin McKie why he thinks a mutation in the human brain 200,000 years ago suddenly made us a super-intelligent species

Robin McKie
The Observer, Sunday 28 March 2010

Colin Blakemore believes the human brain became bigger through genetic accident and not evolution. Photograph: David Hartley / Rex Features

According to Woody Allen, it is his second favourite organ and it absorbs more than 25% of the energy that our bodies generate. But why? For what purposes did the human brain evolve and why does it take so much of our physiological resources? Such questions have absorbed scientists for decades and have now been given an expected answer by Colin Blakemore. In a recent lecture, the Oxford neurobiologist argued that a mutation in the brain of a single human being 200,000 years ago turned intellectually able apemen into a super-intelligent species that would conquer the world. In short, Homo sapiens is a genetic accident.

Most scientists believe we achieved our intellectual status through gradual evolution. Blakemore's intervention will therefore come as a surprise and an upset, although this will not faze the provocative 66-year-old.

So why have you decided to put forward your idea now?

I was asked to give the Ferrier prize lecture at the Royal Society and as this is the society's 350th anniversary I decided to do something special and face up to the issue of the human brain. The question is: why is it so big compared to the brains of our predecessors, such as Homo erectus? Until 200,000 years ago, there had been a gradual increase in brain size among hominins, starting three million years ago. Then, abruptly, there was a remarkable increase of about 30% or so.

How have scientists explained this jump in brain size?

Many have argued that if there was a dramatic increase in brain size, there must have been a fantastic advantage that came with it: improvements in tool construction, more complex language and other cultural changes. In other words, they say simple natural selection explains what happened.

So what is your take on this view?

I think they're fooling themselves. There was very little change in human behaviour at this time, as far as we can see from the fossil record – certainly not one that is explained by a sudden jump in the size of the human brain. These hand-waving arguments about tiny changes in culture explaining the emergence of such a huge change in brain structure just doesn't hold water. It's like arguing that a reptile suddenly developed fully formed wings and then sat around for 200,000 years before suddenly saying: Oh my God, I've discovered I can fly. It's ridiculous.

Read more here/Leia mais aqui: The Observer