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Brain size and intelligence (lemmings.world)

submitted 2 days ago by xuakzon@lemmings.world to c/AskLemmy@lemmings.world

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small/short people, dwarfs have sometimes small heads, homo floresiensis was small, birds have very small heads but prooven denser brain structure. science is "surprised" for example that floresiensis (hobbit) made tools but i can't find any source (as well as personal experience) that small people with small heads are less intelligent. Also, we know that domestication if animals reduces their brain volume and it is thought to be connected with aggressivity and general defence of tweritory or dominance. Also we have some people apparently functioning totally normal with half a brain.

my question is, aren't we still totally misinterpreting size with function? Is that already somewhere in literature? I mean just that aspect of volume, density and mental capacity?

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[–] Neuromancer49@midwest.social 8 points 1 day ago* (last edited 1 day ago) (1 children)

The biggest predictor of intelligence in the animal kingdom is the surface area of brain tissue, not size. You get more surface area by having more folds and bumps (sulci and gyri) on your brain.

Brains are made of neurons and neurons are organized into two types of brain tissue - gray and white matter. Gray matter is where the cell bodies are located, and white matter is where all their connections (axons) are located. Gray matter tends to be found on the surface of all these sulci and gyri, while white matter is located underneath this layer. More surface area = more efficiently connected brain cells.

I don't know of any literature looking at human intelligence related to folds and bumps, but that's not what I studied in graduate school. You have to be careful when looking at the older literature on intelligence because it was fairly prejudiced and designed to prove old ideas of race theory.

[–] xuakzon@lemmings.world 3 points 1 day ago (1 children)

thanks a lot for your contribution and further framing the question. still if you look at floresiensis or the actor who played mini me, what is your guess. sorry for putting it that bluntly but i guess you understand my pure curiosity and brain pain. :))

[–] Neuromancer49@midwest.social 1 points 1 day ago

There are types of dwarfism that can lead to mental impairment, but not all. Calling on a personal anecdote, I work in a highly technical field, with two colleagues who are little people. I know one of them holds a PhD.

There are correlations between height and intelligence, but being tall doesn't make you smart, it just means you have access to good nutrients that make you both tall and smart. Human ancestors had different diets - once we figured out how to control fire, use tools, amd farm, our caloric intake practically exploded. Evolution then took over, and now our brains consume something like 20% of our daily caloric intake. So, feed your brain and stay curious!

[–] Lembot_0006@programming.dev 4 points 2 days ago (2 children)

I heard that many zones of the brain don't have a designated purpose and can be repurposed in the case of the damages. So size is more about reliability, backups, etc than a criteria of pure intellect.

[–] Neuromancer49@midwest.social 4 points 1 day ago

I would bet, dollars to donuts, it's less that those parts of the brain have no designated purpose, and more that we just don't know them. Brains are really complicated and the tools we have to study them aren't perfect.

Part of what makes this so difficult to study is that we have very few regions of the brain with a single dedicated function. Outside of sensory and motor parts of the brain, many brain regions seem to do multiple things. Most function of the brain depends on networks of multiple regions firing together. Some regions of the brain can participate in multiple networks.

Then, consider that our best tool to study brain networks, functional magnetic resonance imaging, has poor spatial resolution. You may see the same region of, say, a cubic millimeter of brain tissue, active during two different cognitive tasks like memory and motor control, but it could be different populations of cells that happen to be next to each other. Also, functional MRI is going through some growing pains right now - we just learned in 2026 that fMRI signal isn't necessarily measuring neural activity as well as we thought, so it's back to the drawing board for a lot of these studies.

[–] xuakzon@lemmings.world 2 points 1 day ago

interesting aspect. i am convinced that is part of the answer. thanks.