When contrasting the human brain with that of apes and other related animals, the differences are mainly physiognomic, highlighting size. However, to understand the uniqueness of human intelligence, science delves into new areas of research. It explores not only morphology, but also genetic aspects, neuronal “wiring” and functional complexity. This more holistic approach allows for a more complete understanding of what drives human intelligence beyond the theory that bigger brains are smarter.
Some theories of the past are wrong
Some scientists of the past made mistakes in the name of science. Perhaps they did it not intentionally, but because they were convinced of their theories. One of them was Arthur Keith, a famous anatomist and anthropologist who lived at the beginning of the 20th century.
He said that man was originally from Europe and not from Africa, as we know today. However, Keith was a staunch racist and mixed science with those ideas, leading him to formulate erroneous theories.
Keith argued that man differed from other primates when his brain became larger. Homo, according to the scientist, must have had a brain with a minimum volume of 600 to 750 cubic centimeters. Size that for Homo sapiens, that is, us, should have been 900 cm³. According to his argument, bigger brains are more intelligent, a smaller brain could not have the power to reason logically.
Is it the size that is most important?
While it is true that Homo sapiens has a larger brain, science is currently investigating this topic from another perspective. The evidence emerges from the fields of neuroscience and genetics. From these points of view, brain size is not the factor that determines intelligence.
The size of the human brain is large, even compared to the rest of our body. It is also true that it is the largest of all primates. In the last six million years, our brain has not stopped growing thanks to evolution.
However, changes in the “wiring” of our brain, the way certain genes are turned on and off or the functioning of our neurons, are as important, or more so, than the size of our brain.
In comparison, our brain, which weighs about 1.5 kg, is two to three times smaller than that of an elephant. And up to six times that of whales and dolphins.
Characteristics of our brain
Our brain is more complex, with 86 billion neurons and 85 billion non-neuronal cells. It represents 2% of our body mass, and consumes about 20% of our calories.
Humans and chimpanzees share 99% of DNA. However, the difference between them is not only that 1%.
Geneticists identified areas of the genome that radically differentiate them and that are exclusive to humans. Many of these areas can perform functions in our brain.
From what science currently says, larger brains do not determine greater or lesser intelligence.
