Brain size and the relation to behavior

Compared to other animals, the primates (mammals) have larger brains than expected with their body size. However, there is also a difference between the various mammals. These differences are linked, for example, to the size of the brain, but also to the structure. It was assumed that the size of the brain is related to the size of the body. The brain of man is therefore larger than that of, for example, a chimpanzee. However, this rule does not fully apply, relatively speaking. The human brain is more than three times the size of the brain of another primate that has the same body size. The human brain is about five times larger than that of a monkey of the same body size. The difference in size of the brain differs a lot between the mammals, for example, the difference between humans and chimpanzees is many times greater than the difference between a chimpanzee and a mole. While the difference in body size between chimpanzee and a mole is many times greater than that between a chimpanzee and a human being.

Relative size of the brain in relation to complex behavior
Increase in the relative size of the brain is related to an increase in complex behavior. In order to understand what this increase in complex behavior is all about, it is important to consider which parts of the brain have become larger or better developed. This mainly concerns one specific part in the frontal lobe: the prefrontal cortex. This part of the brain is five times larger in humans than in chimpanzees. This remains the case if you take into account that the human cortex is generally larger, even then the prefrontal cortex in humans takes up more than twice as much space than in a chimpanzee. There is also a big difference in the temporal lobe. This lobe is involved in language processes and is four times as big in humans than in chimpanzees.

Differences in intelligence and relative size of the brain
Mental capacity and differences in intelligence are related to the relative size of the brain. For example, the above-mentioned mammals: the mole, the chimpanzee, and the human. The mole leads a simple life in search of food under the ground. The chimpanzee, on the other hand, already leads a more complex life, he makes simple tools, learns simple gestures and has a social life. However, the gap between the chimpanzee and man remains great. The human brain must therefore contain more complicated and additional capacities than that of a chimpanzee. Here the prefrontal cortex plays a role again, it is much larger in humans. The prefrontal cortex has to do with the functioning of reason and planning. Due to the size of the temporal lobe, the linguistic ability of humans is also great.

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