The evil that chefs do lives after them. Until his death on 24 June, the Galapagos turtle known as Lonesome George was the rarest creature in the world, his forebears hunted to oblivion by hungry sailors.

 

Then there is the deadening legacy of the Rio+20 summit – an “epic failure”, as Greenpeace put it. We might not be eating rare species to the brink of extinction any longer but, as a result of our activities, climate change will drive many species to their doom. And it is clear that the chefs are to blame for this, too.

 

To see why, we have to take a closer look at the human brain. In order to harness resources that ensure our survival, human beings have learned a range of skills that makes us uniquely dangerous. We learned how to domesticate animals, tame wild land for agriculture, build cities and design and construct machines for rapid travel over vast distances.

 

It takes extraordinary cognitive abilities to pull all this off. Which makes it all the more remarkable that the human brain is not particularly unusual. An analysis published in the 25 June edition of the Proceedings of the National Academy of Sciences of the United States of America shows that a human being’s brain is just a scaled-up version of the generic primate brain.

 

The human brain has about 85 billion of the glial cells that provide a scaffold for the information-processing neuron cells – of which there are roughly 86 billion. This is the same ratio of processing cells to support cells as found in other primate brains. The common report of ten (sometimes 50) times as many neurons as support cells is false.

 

Then there is the claim that the human cerebral cortex, the outer covering of grey matter, is particularly rich in neurons. It is not: the ratio of normal, cerebellar neurons to cortical neurons is the same in human beings as in every other mammal, adjusting for how the density of neurons varies with brain size. 

 

Brain size does differ wildly across nature. But many creatures have large brains only because they have large neurons; a tenfold increase in the number of neurons in a rodent cortex results in a fiftyfold increase in brain size. Primates, on the other hand, pack small neurons: ten times as many neurons give a brain only ten times bigger.

 

Basically, our advanced cognitive abilities arose because we have packed the largest number of neurons into one network. Our brain size seems to have crossed a threshold, a tipping point that switches on the kind of innovative thinking that launches technological development on a scale that can change a planet.

 

 

The thing is that those extra neurons use up a lot of calories, calories to which the great apes can’t get access. Neither could the earliest human beings. But somewhere in early human evolution, we managed to find the extra few hundred kilocalories a day necessary for our brain expansion. How did we do it? By harnessing fire. Put simply, cooked food yields much more energy than raw.

 

So, it was the first chefs who created the modern human – and all the devastation its brain has unleashed. The cooking of Galapagos turtles was only the final act of the chefs; without the first of their kind, Lonesome George would not have been lonesome at all. If we hadn’t learned to cook, we would never have been able to come up with the means of global travel, prompting us to look for food in far-off places.

 

Without roasted meat, there would have been no Industrial Revolution, no devastation of swaths of Planet Earth’s animal and plant species, no catastrophic climate change. The politicians are off the hook – bring me the head of Jamie Oliver. 

 

Michael Brooks’s “Free Radicals: the Secret Anarchy of Science” is published by Profile Books (£12.99)