Some scientists believe that the human brain has reached the limit of evolution, we can not physically be any smarter.

The human brain

Modern human brain weighs approximately  2% of the total body weight, but consumes 20% of total body energy. So any further evolution of the brain can overwhelm the  energies stored in our body. Experts believe that over millions of years of evolution, the human brain is getting larger and more clever, but in the future this trend is unlikely to continue.

Picture of two Neanderthal ancestors.

In order to save excessive energy consumption, some scholars even believe there may be a chance that in the future  human brain will experience atrophy, bring our brains back to the size of Neanderthal ancestors‘ level.

Comparison of the Human brain (top) and the Neanderthal ancestor’s brain (bottom). Notice the size difference of the two brains.

Simon Laughlin, the  neurobiology professor at Cambridge University told The Sunday Times: ‘We have demonstrated that brains must consume energy to function and that these requirements are sufficiently demanding to limit our performance and determine design.”

He mentioned that the high level of abstract reasoning and thinking will consume a lot of energy. When the brain is performing work, it needs to quickly retrieve a variety of information sources, however, the restrictions on energy consumption limits the capability of the brain to process a lot of information at a given time.

Laughlin in his published book “Work Meets Life“ describes in detail the mechanism of brain cells consumption of energy. In his book, he points out the part of the brain that is responsible for abstract thinking is the most powerful site of energy consumption. He even pointed out that the human brain may also shrink in the future, if humans believe that we should provide portions of energy consumed by the brain to other parts of the body.

Ed Bullmore, professor of psychiatry at Cambridge says that the cleverest people have the best wiring, with messages carried very fast between different parts of the brain. He found that impulses travelled fastest in more intelligent individuals and slower in those who were less intelligent. However it would require a lot of energy and oxygen, and as mentioned before, we can’t possibly provide that much energy to the brain, something that energy drinks nor coffee can provide. Ed Bullmore says “You pay a price for intelligence. Becoming smarter means improving connections between different brain areas but this runs into tight limits on energy, along with space for the wiring.” therefore we cannot get any cleverer.