Evolution made 'weedy' humans choose brains over brawn
Humans evolved to be weedy in the energy battle between brains and brawn, research suggests.
A study has found that over the course of evolution, essential molecules had changed even more rapidly in human muscle than in the brain. The rate of change in muscle was 10 times that seen in our closest animal cousin, the chimpanzee.
In contrast, the molecules in the human brain had evolved four times faster.
The scientists believe human muscle needed to alter drastically to free up energy for the brain becoming puny.
Lead researcher Dr Kasia Bozek, from the CAS-MPG Partner Institute for Computational Biology in Shanghai, said: "Our results suggest a special energy management in humans that allows us to spare energy for our extraordinary cognitive powers at a cost of weak muscle."
The scientists focused on the evolution of metabolites – molecules such as sugars, vitamins, amino acids and neurotransmitter nerve signalling chemicals with key roles in the way the body functions.
"Metabolites are more dynamic than the genome (genetic code) and they can give us more information about what makes us human," said co-author Dr Philipp Kaitovich, also from the Shanghai team.
The researchers carried out tests on macaque monkeys to show the muscle changes were not the result of human lifestyle.