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12 Interesting Facts About Brains

Last Reviewed and Updated on June 7, 2022

Brains are the control center of your body and also the most complex organ in your body. There is still a lot to learn about how they work, but these facts about brains will give you some insight into what we already know.

Human brain image

Ready to learn more? Read these cool facts about brains.

1. Adult human brain weights about 3 pounds (1.3kg)

The human brain grows the fastest in the first year of your life (tripling the size since birth) and will gain most of its weight (and size) by the age of 3. Most of the weight is gained by the age of five to six, however, the brain still grows slowly until the 30s or 40s.

2. After the brain is done growing it starts shrinking

Your brain will continue growing until the 30s or 40s and after it is fully grown, the process takes a turn. The brain starts shrinking, even more so as you age. This shrinkage isn’t dramatic and new studies show, that there is less shrinkage in a healthy brain.

3. Bigger brain doesn’t mean higher intelligence

Bigger doesn’t automatically mean better. Einstein’s brain for example was weighted at 2,712 pounds / 1230 grams, which is lower than average brain size and we can without a doubt claim he exhibited higher than average intellectual skills.

There have been studies made on this subject and while the size of the brain can have some correlation with intelligence, the size alone isn’t enough or even relevant. The size of the brain can have a modest effect on intelligence. The correlation between size and intelligence was shown as weak.

Human brain size

4. On average men’s brains are 10% larger than female brains

Male and female brains are more alike than they are different, however, there is a noticeable difference in the overall size. While there is a difference in absolute sizes, there isn’t a difference in the body-to-brain ratio in both genders.

5. Neanderthal had a bigger brain than modern human

While examining a brain of a neanderthal is not possible for obvious reasons, researchers used skulls of neanderthals and compared them to those of modern humans.

A study was made, reconstructing the neanderthal brains with CT scans, to create casts of their brains. It was concluded neanderthal brains were slightly bigger than homo sapiens brains.

6. Brain consumes up to 20% of the energy used by the human body

Considering the brain on average accounts for about 2% of body mass the energy consumption is pretty high. In fact, it’s the highest of any organ in your body.

7. On top of energy, it also receives 15% cardiac output and 20% of oxygen

The brain really is a high-maintenance organ.

8. You can (potentially) live with half a brain

Now, this is an interesting fact about brains, you can live even when missing a half.

Cerebellar agenesis means a complete lack of the cerebellum, a part of the brain that takes up almost half of it. Its role is to maintain balance and posture, something that is vital for all of our physical movement. Yet this condition, although extremely rare, has been observed in people and they led almost normal lives. Fascinating isn’t it?

Aside from that, even when a part of the brain is removed, life can, not in all cases, continue as normal.

There is a lot of research done on the human brain, but a lot still remains unknown.

9. There are no pain receptors in the brain

The brain itself has no pain receptors, so it can not hurt. The covering around the brain, the bones as well as scalp, nerves and blood vessels, and muscles have pain receptors and this is where you feel the pain when you have a headache.

10. Sweating and dehydration can temporarily shrink the brain

One of the more interesting facts about brains is their size changes depending on hydration. The brain, like most of our body, consists mainly of water, and dehydration can temporarily shrink your brain. Rehydrate and the brain will return to its original size.

11. Considering the body to brain ratio, humans have the biggest brains of all animals

The human brain on average account for 2% of body mass, which is more than any other animal. Looking by size alone, we are topped by quite a few animals, the winner being the sperm whale as their brains weigh about 18 lb / 8kg.

12. We don’t “only use 10% of the brain”

A popular myth that humans only use 10% of their brains is just that, a myth. We use virtually every part of the brain.

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