eli5:Why brain size doesnt actually matter?
In: Biology
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Your brain isn’t a single, general purpose computer that can dedicate its processing power however it wants, rather, its a bunch of single purpose processors that have been networked together. Each of those processors can do one (1) and only one (1) thing.
Most of what your brain is doing is processing sensory information and figuring out how to move around. That’s true for all animals – the vast, vast majority of an animal brain’s processing power is spent doing the calculations necessary for basic life stuff, like determining “what am I looking at?” or “how do I move to the thing in front of me?”
Usually what happens when an animal’s brain gets bigger is that it does one of those basic life functions better, not that it gets smarter. For example, eagles have relatively large brains for birds. But eagles are dumb as hell – 100% of the increase in their brain size relative to other birds went into processing visual data better and as a result eagle’s have much better eyesight than you would expect for an animal of their size.
Humans are another good example of that. The human brain is *substantially* larger than other primate brains. And while humans are certainly smarter than other primates, they’re not substantially so. Nearly all of the increase in processing power that humans gained from having a larger brain went into two things:
1) Allowing humans to walk upright
2) Allowing humans to use their hands with substantially better precision than other primates
If you’ve ever wondered why computers are so much better at math than people are – this is why. Performing extremely complex mathematical calculations requires a trivial amount of processing power. But humans don’t really have a dedicated math part of their brain – you do math by piggybacking off the part of your brain responsible for telling you how many fingers are currently performing a task. That is an *extremely* small part of your brain with an *extremely* small amount of processing power available to it, and as a result the amount of processing power that your brain can dedicate to math is almost non-existent.
On the other hand, computers have a really hard time making a robot walk around because that’s an extremely processing power intensive activity. Humans don’t have a problem with that because that’s what 99% of your brain is hard wired to do.
This is also why its so easy for humans to do math in base 5 and base 10 systems – you have 5 fingers on each hand and 10 fingers total, so you’re able really only able to process large numbers in batches of 5 and 10. When computers are doing math they use a base 16 system, because they process numbers in batches of 16, so that’s the easiest numbering system for them to use.
It doesn’t, not really. We used to think this was all-important, but clues started arising that made us think differently. The obvious clue was that we saw evidence that other humanoid species had larger brains than modern humans, one of the ideas behind our evolution was that we were able to ‘outsmart’ other human populations and that was our main evolutionary advantage to dealing with a hostile environment. It is hard to hold the idea that bigger = better when our ancestors died out and had larger brains than we did.
Then there is the other obvious problem, there are some massively high IQ people with relatively small craniums.
Further research shows us that animals that have very small brains can be extremely intelligent. The Raven (or crow), has started to be seriously studied because it can do so well on intelligence tests originally designed for mammals.
[https://www.sustainability-times.com/environmental-protection/ravens-possess-human-like-features-of-intelligence/#:~:text=Recently%20scientists%20confirmed%20something%20even,by%20humans%20and%20possibly%20chimpanzees.&text=In%20other%20words%2C%20a%20raven,another%20animal%20might%20be%20thinking](https://www.sustainability-times.com/environmental-protection/ravens-possess-human-like-features-of-intelligence/#:~:text=Recently%20scientists%20confirmed%20something%20even,by%20humans%20and%20possibly%20chimpanzees.&text=In%20other%20words%2C%20a%20raven,another%20animal%20might%20be%20thinking).
[https://www.nationalgeographic.com/news/2017/07/ravens-problem-solving-smart-birds/](https://www.nationalgeographic.com/news/2017/07/ravens-problem-solving-smart-birds/)
So modern thought tells us it isn’t really about the *size,* rather it is about the *configuration* of the neurons. This leads us to rethink intelligence in animals like octopuses (yes, that is the correct plural form of octopus) who have **more than one brain.**
It does but there are many other factors.
It’s like saying hard drive size don’t matter. I does, usually bigger hard drive means more storage in it, but it’s not the only parameter so sometimes a small hard drive has more storage than a bigger one.
Other answers are quite complex so I may be able to simplify it.
It does matter, but it’s also very dependent on your body size. The most important thing is brain to body size ratio. More brains you have to less body, the smarter you can be. You essentially have more “processing power” or bang for your buck. This is a very very basic explanation though!
Another redditor explained this very well already, but I will also add that it is a well documented phenomena that when parts of the brain are damaged, other parts of the brain will take over the duties of the damaged parts. We have no idea how this happens.
There was a case of a man who had a substantial hole in his brain and the space was filled with a huge benign cyst. He functioned quite well and the parts of his brain that did exist took over all the traditional functions of our brain and it did it so well that no one noticed until a test was done for an unrelated condition later in life.
I think the simplest way to look at it is it’s not the size of the brain, it’s the number of neurons and the connections between them. So neuron density is more important than absolute brain size.
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