Brain
11 Mar 2019

The Brain

Our brains are wrinkly, weigh about three pounds and are approximately fifteen centimetres in length. Size wise your brain is slightly bigger than your two fists. But how big are the brains of other animals?

Can you really have a brain the size of a pea?

A horse’s brain is the size of a grape fruit. 

A dog’s brain or that of a stegosaurus is the size of a lime. Despite that you can still teach the dog to do tricks. Not sure about the Stegosaurus though. 

A rat’s brain is the size of a penny and very smooth.

A squirrel has a walnut sized brain but animals can have brains smaller than a pea. Like hummingbirds. Whose brains are smaller than a pea. 

So, being pea-brained or even less than that is totally possible. But, how does size equate to intelligence? And how relativity intelligent are we compared to our brain size? 

Mice, dolphins and humans

If you believe Hitchhikers Guide to the Galaxy, humans are only the third most intelligent creature. Humans have a brain to body mass ratio of 1 to 40, the same as a mouse and not far different from dolphins. 

Dolphins are in fact the second most intelligent creature on the planet, after humans, just as Hitchhikers Guide to the Galaxy suggests. It is thought they are more intelligent than chimpanzees, who were previously thought to occupy that position. Dolphins have the ability to think about the future as well as personalities and a sense of self. They are also thought to be able to recognise themselves in the mirror and check they look okay, you know, like adolescent humans. 

Chimpanzees are thought to be able to attain the intelligence levels of two to three year old children and are actually the third most intelligent in the animal kingdom but what about mice? Douglas Adams touted them as the most intelligence beings on the planet. Though untrue it does make you wonder why. Mice are certainly clever and it’s pretty impressive when you consider how much smaller they are than humans. They are social creatures and quite possibly capable of showing affection towards other mice and something akin to sympathy when another mouse is suffering. They are curious and can learn tricks and be taught to recognise their name. 

Humans then are clever but not perhaps as clever as we might think. What makes us quite different to other animals is we can speak. Other animals do speak but not in the same way and we certainly can’t tell what they’re saying. That’s why we didn’t listen to the dolphins’ warning. Sigh…

Let’s have a closer look at the human brain now and how it works.

The Human Brain 

Our brains have two hemispheres; a right and a left. That’s why it looks like it has a line drawn down the centre. Sounds simple. To make it more confusing, remember that the left hemisphere controls the right side of your body and vice versa. 

The wrinkly appearance of the brain is actually a good thing. Remember the rat’s brain is smooth. The folds of our brain mean, unlike the brain of a rat, it can contain much more information, because there is a greater area (more folds) on which to store it. 

So here’s the trickier science bit. The brain is split into many different sections but some of the main ones are the frontal lobe which is at the front, the temporal lobe which sits below it, the parietal lobe sits behind the frontal lobe, above the occipital lobe which is above the cerebellum. Our frontal lobe controls our cognitive skills like emotions, language, memory and problem solving. Our temporal lobe deals with sensory input which includes signals from the nose and ears. Meanwhile the parietal lobe brings together information from different senses. The occipital lobe processes visual information and the cerebellum, which means ‘little brain’ controls things like movement and balance. 

The brain display at Thinktank featuring model head and brain

And then there is grey matter and white matter. What does that mean though? The brain looks kind of pink! White matter is the paler matter of the brain and spinal cord and consists of neurones (or nerve cells) that are covered in myelin sheaths. Grey matter, as you may have guessed is the darker tissue of the brain and spinal cord and unmyelinated. Myelination means there is a myelin sheath around the axon of the nerve cell and myelin is a fatty insulating sheath. 

Our brains do change over time too. The brains of older people do actually shrink but not as much as we previously thought. It starts shrinking very slightly from age twenty and obviously shrinks more in conditions like dementia. Stimulating your brain, getting enough sleep and not drinking too much can help preserve the brain. 

The brain is a special organ. We really need it; to think, to feel, to move… and it needs fuel. And what does the brain run on? Glucose. 

But that isn’t an excuse to buy another chocolate bar. There are plenty of healthy alternatives. Even if the chocolate bar is nice… 

If you want to find out more, you can visit our Medicine Matters gallery at Thinktank !

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