Why are our brains so big?

Published 19 May 2017

Table of content


It is true that humans have a darn big brain in relation to the body weight. The human brain is larger than any other primate which walked this planet. In comparison to the earliest human relatives, we have twice the brain size. Most of the neuroscientists such as Stephen Cunnane have implied that the diet of humans is primarily responsible for the size of brain. Since the evolutionary days of human beings, they have consumed food that was rich in iron, iodine and other minerals that help develop brain. This caused the process of brain expansion of human beings to be initiated. There are more pros of a larger brain size than the cons.

Advantages of Large Human Brain

Being the most complex organ of the body, the large human brain does not only provide us with a balance while walking, swimming, driving and running, but also plays other roles. The primary role of the human brain is to house the neurons their communication in the neural network. As many as 15 million neurons interact with each other and exchange information in the form of electrical signals (The Franklin Institute Online).

Other scientists have also argued that larger brain size allows better control of the body, limbs and makes the senses work better. Larger brain size has also allows the humans to make the decision between right and wrong.

Other animals with smaller brain sizes depend upon instincts to make their decisions, whereas, the human brain conducts a cost-benefit analysis of the situation and then decides how to react. The other big advantage of large brain size is the gift of consciousness. Although the word consciousness has many different meanings and there are many controversies about consciousness, but science has proved that only living beings possess the attribute of consciousness. And the bigger the brain size is, the larger the neural network is and hence the consciousness is also highly developed.

Another proposed advantage of a brain larger in size is that the species with larger brain sizes can live longer lives and can reproduce more number of times. The human brain size is large and hence the brain allows humans to live longer lives and produce more number of times (E Science News).

Disadvantages of a Bigger Brain

A large brain size involves the cost of higher energy consumption which in turn increases the level of metabolism in the human body. Higher energy requirements also involve greater requirement of food intakes because of which the humans have to eat frequently throughout the day to keep energetic.

When a human child is born, the body consists of 14% fat. A human child is the healthiest amongst all the primates’ newborns. According to a theory, the fat of the body is used in the development of the brain. The disadvantage here is that the development and training of the brain in human child takes a lot of time.

Another obvious disadvantage of a large sized brain is that it is not easy to protect it from damage as egg-headedness makes our brain delicate and susceptible to injuries. It is difficult to avoid injuries as the size is bigger and the probability of hitting it to another object is also higher.


Brain is the most important part of the human body and is the only organ that makes us unique and distinct from other animals and primates. The large brain size is responsible for our long lives and our consciousness but it is more difficult to protect the brain from damage as the chances of hitting external objects is higher.

Works Cited

  • E Science News. The protective brain hypothesis is confirmed.
  • The Franklin Institute Online. The Human Brain.
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