IF human beings had not invented cooking as a way of increasing the number of calories they consumed, they could only have supported the 86 billion neurons in their big brains by spending an impossible nine hours or more each day eating raw food, according to a scientific paper published on Monday.

The research, the authors suggest, explains why great apes such as gorillas, which can have bodies three times the size of humans, have considerably smaller brains. Though gorillas typically spend up to eight hours feeding, their diet influenced an evolutionary tradeoff between body and brain size; supporting both big bodies and big brains would be impossible on a raw food diet.

The brain is so energy-hungry that in humans it represents 20 per cent of the resting metabolic rate, even though it only represents two per cent of body mass, suggest Professor Suzana Herculano-Houzel and Karina Fonseca-Azevedo of the Institute of Biomedical Sciences at the Federal University of Rio de Janeiro.

“Why are the largest primates not those endowed with the largest brains as well? Rather than evidence that humans are an exception among primates, we consider this disparity to be a clue that, in primate evolution, developing a very large body and a very large brain have been mutually excluding strategies, probably because of metabolic reasons.”

Gorillas, they suggest, already live on the limit of viability, foraging and eating for 8.8 hours a day, and in extreme conditions increasing this to as much as 10 hours a day.

In contrast, humans’ move to a cooked diet, possibly first by Homo erectus, left spare energy which allowed further rapid growth in brain size and the chance to develop the big brain as an asset rather than a liability, through expanded cognitive capacity, flexibility and complexity.

“We propose that this change from liability to asset made possible the rapid increase in brain size that characterises the evolution of Homo species, leading to ourselves. We may thus owe our vast cognitive abilities to the invention of cooking — which, to my knowledge, is by far the easiest and most obvious answer to the question, what can humans do that no other species does?” Herculano-Houzel commented on the paper, published in the journal PNAS, the Proceedings of the Natural Academy of Sciences of the USA.

The paper builds on research by Richard Wrangham, a British primatologist, now professor at Harvard University, who suggested the invention of cooking was a crucial point in human evolution.

“Human guts are about 60 per cent of the expected size for a primate. The small size of human guts means that we have some spare energy, which contributes to explaining how we can afford a relatively large brain. And the reason we have been able to evolve small guts is that we have been able to rely on eating our food cooked.” — The Guardian, London

Opinion

Editorial

Desperate measures
Updated 27 Dec, 2024

Desperate measures

Sadly in Pakistan, street protests and sit-ins have become the only resort to catch the attention of a callous power elite.
Economic outlook
27 Dec, 2024

Economic outlook

THE post-pandemic years, marked by extreme volatility in the global oil and commodity markets as well as slowing...
Cricket and visas
27 Dec, 2024

Cricket and visas

PAKISTAN has asserted that delay in the announcement of the schedule of next year’s Champions Trophy will not...
Afghan strikes
Updated 26 Dec, 2024

Afghan strikes

The military option has been employed by the govt apparently to signal its unhappiness over the state of affairs with Afghanistan.
Revamping tax policy
26 Dec, 2024

Revamping tax policy

THE tax bureaucracy appears to have convinced the government that it can boost revenues simply by taking harsher...
Betraying women voters
26 Dec, 2024

Betraying women voters

THE ECP’s recent pledge to eliminate the gender gap among voters falls flat in the face of troubling revelations...