The brain has helped humans evolve into a successful species, and it has done this through several internal trade-offs. Scientists at the University of Cambridge managed to throw light on one such trade-off when they studied how resources, particularly glucose, were shared between the brain and body organs involved in physical performance.
Their study, reported in the journal Scientific Reports , showed that when mental and physical performances are in direct competition, the brain takes less of a hit, suggesting that more energy is diverted to the brain than to body muscles. The findings, the scientists said, supported the “selfish brain” theory of human evolution.
Their investigation into the trade-off showed that mental ability is less affected than physical capacity. It takes lot of energy to run the sophisticated grey matter of the brain, and that comes at an evolutionary cost. According to them, this preferential allocation of glucose to the brain might have helped homo sapiens survive and thrive.
Researchers at the university’s Phenotypic Adaptability, Variation and Evolution (PAVE) research group carried out a study of 62 male student volunteers, all excellent rowers. The participants performed two separate tasks: a three-minute word recall test and a three-minute power test on a rowing machine.
They then performed both tasks together. A comparison of the individual scores showed that the challenge of rowing and remembering reduced both physical and mental performance. However, the change in recall was significantly less than the change in power output. The drop in physical power was on average 30 per cent greater than the drop in cognitive function. The findings showed that the brain could prioritise its own energy needs over those of peripheral organs, such as skeletal muscle.
"A well-fuelled brain may have offered us better survival odds than well-fuelled muscles when facing an environmental challenge,” said Danny Longman, the study’s lead author from the PAVE team.
T.V. Jayan
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