Study: Humans’ Faster Metabolism Enables Larger Brains

Human brain's large enough energy is the result of the ancient ancestors' metabolic gear shift, enabling the humans to burn calories at a much faster rate than any other primates. The shift, according to research, came after the human ancestry broke away from the other primates, which led to enough energy to run bigger brains and live longer.

The human brain is what separates the humans from other apes, and this event emerged when the ancient human ancestors largely increased their metabolism.  A team of researchers from the US gauged the metabolic rates of over 100 people, then made a comparison against the same measurements gathered from the gorillas, orangutans, bonobos and chimpanzees. The team discovered that in terms of weight, humans burned calories at a much faster rate compared to other primates, and the energy was potentially spent on running the brains.

A human brain is over twice the measure of an ape brain at 1200ml, and although rising metabolic rate is a high-risk strategy of evolution, the advantages of a larger brain could have prevailed over the disadvantages. As explained by the author of the study at the Hunter College, Herman Pontzer, each gram of the brain uses a massive weight of calories, HNGN reported.

According to Christopher Kuzawa of Northwestern University, the study offered a clear proof that humans spend more energy compared to other apes, providing an explanation on how humans in general manage give birth to several children while offsetting the costs of the expensive brains. However, Kuzawa added that these findings were not final yet in the aspect of the energy's role in human lives, including how such costly brains managed to evolve.

The human brain is responsible for the 66% of the base metabolic rate of humans during childhood, which is more than three times than those in the adults. Since the study centers around the adults, it misses the significant differences in childhood, when learning is even more demanding of the human brain, Science Daily reported.