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Thread: Smarter Brains Are Blood-Thirsty Brains.

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    Quote Originally Posted by JMcB View Post
    Smarter Brains Are Blood-Thirsty Brains.

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    A University of Adelaide-led project has overturned the theory that the evolution of human intelligence was simply related to the size of the brain -- but rather linked more closely to the supply of blood to the brain.

    http://www.ancient-origins.net/news-...-brains-006565
    That is true in the long run, but among humans today there is a positive correlation between brain size and intelligence. In order for that to be overturned you would need to find an extensive study which finds a negative correlation or something like that. With that being said- the brain size alone only accounts for some of the variance, I would like to add something else to this thread:
    https://www.nature.com/articles/s41467-018-04268-8
    Looks like low density also helps. So one would still expect a random person with a more massive, well structured and lower density brain to be more intelligent than a smaller and denser brained person.

    Perhaps you can also expect a person with a regular brain mass and low brain density to be more intelligent than someone who has an above average brain mass without the low brain density (and less optimal organization).
    Last edited by Aleph; 10-20-2019 at 03:24 PM.

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     MethCat (07-07-2020)

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    No, brain size is not necessarily related to intelligence (let's not forget that there are many types of intelligence). Birds are well-known to have tiny brains, yet some species like ravens are even more intelligent than your average dog or rat. Ravens and crows are said to have the cognitive abilities of a seven-year-old human. So they're not stupid, what happens is that their brains are organized differently (there's less space between neurons in birds and reptiles in general than in mammals). Men also have on average bigger brains than women and they aren't more intelligent as a whole.

    https://medicalxpress.com/news/2016-...ird-brain.html
    https://www.theguardian.com/science/...ear-old-humans

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    Quote Originally Posted by Milkyway View Post
    No, brain size is not necessarily related to intelligence (let's not forget that there are many types of intelligence). Birds are well-known to have tiny brains, yet some species like ravens are even more intelligent than your average dog or rat. Ravens and crows are said to have the cognitive abilities of a seven-year-old human. So they're not stupid, what happens is that their brains are organized differently (there's less space between neurons in birds and reptiles in general than in mammals). Men also have on average bigger brains than women and they aren't more intelligent as a whole.

    https://medicalxpress.com/news/2016-...ird-brain.html
    https://www.theguardian.com/science/...ear-old-humans
    True. Bird brains are different in terms of physiology and etc in comparison to Mammalian brains, but that doesn't mean they're less intelligent than Mammals considering that there are bird species that can even outperform Apes in intelligence. People back in the day claim that Dinosaurs are not intelligent due to them having smaller brain cases than Mammals, and yet, Birds are considered to be living Dinosaurs which greatly suggest that non-Avian Dinosaurs would have been much more intelligent than previously thought.

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     Milkyway (10-21-2019)

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    Quote Originally Posted by Milkyway View Post
    No, brain size is not necessarily related to intelligence (let's not forget that there are many types of intelligence). Birds are well-known to have tiny brains, yet some species like ravens are even more intelligent than your average dog or rat. Ravens and crows are said to have the cognitive abilities of a seven-year-old human. So they're not stupid, what happens is that their brains are organized differently (there's less space between neurons in birds and reptiles in general than in mammals). Men also have on average bigger brains than women and they aren't more intelligent as a whole.

    https://medicalxpress.com/news/2016-...ird-brain.html
    https://www.theguardian.com/science/...ear-old-humans
    Within humans there is an small, yet consistently positive correlation between brain size and IQ. Pretty much every study that I have seen claims that a small part of the variation in intelligence comes from brain size. Women's brains are arranged differently and so you have to account for that (though they do seem to have a lower variance than men do- maybe a byproduct of this arrangement). Though brain size would also include non-neurons (thus weakening the correlation between brain size and intelligence), so neural count and neural arrangement when accounted for properly will account for a much larger variance than raw brain size alone.

    Your second link shows that crows can match 5 to 7 year olds in one specific class of tasks. I don't think that they will do all that well in a bunch of other tasks associated with general intelligence and learning. Animals having some understanding of basic causality isn't surprising since animals and like birds and mammals also have a basic sense of numeracy (but all of that is fairly basic). Speaking of smart birds, the first link says that there is perhaps a relation between neural number and intelligence, which is why birds are smarter than what we would expect given their cranial capacity- they have smaller neurons which aren't as few in number as one would expect. It literally argues for a link between a high neural count and intelligence. Maybe if birds like crows had large neurons (with the same cranial capacity and hence a lower number of total neurons) they would't be as smart as they are.

    Though I have yet to see a source which shows that neural size in humans can vary as much as the variance between mammal neurons and bird neurons, so the smaller human brains probably don't have a large number of small neurons that birds have.

    From the first link:
    "Scientists were left with a generally unsatisfactory fallback position: Avian brains must simply be wired in a completely different fashion from primate brains. Two years ago, even this hypothesis was knocked down by a detailed study of pigeon brains, which concluded that they are, in fact, organized along quite similar lines to those of primates.

    The new study provides a more plausible explanation: Birds can perform these complex behaviors because birds' forebrains contain a lot more neurons than any one had previously thought - as many as in mid-sized primates."
    High neural count (based on broader observations of many species) + low neural density (as seen in comparison between different humans-> which in turn is associated with a more efficient neural structure) seem to be the key to high intelligence.

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    Quote Originally Posted by Aleph View Post
    Within humans there is an small, yet consistently positive correlation between brain size and IQ. Pretty much every study that I have seen claims that a small part of the variation in intelligence comes from brain size. Women's brains are arranged differently and so you have to account for that (though they do seem to have a lower variance than men do- maybe a byproduct of this arrangement). Though brain size would also include non-neurons (thus weakening the correlation between brain size and intelligence), so neural count and neural arrangement when accounted for properly will account for a much larger variance than raw brain size alone.

    Your second link shows that crows can match 5 to 7 year olds in one specific class of tasks. I don't think that they will do all that well in a bunch of other tasks associated with general intelligence and learning. Animals having some understanding of basic causality isn't surprising since animals and like birds and mammals also have a basic sense of numeracy (but all of that is fairly basic). Speaking of smart birds, the first link says that there is perhaps a relation between neural number and intelligence, which is why birds are smarter than what we would expect given their cranial capacity- they have smaller neurons which aren't as few in number as one would expect. It literally argues for a link between a high neural count and intelligence. Maybe if birds like crows had large neurons (with the same cranial capacity and hence a lower number of total neurons) they would't be as smart as they are.

    Though I have yet to see a source which shows that neural size in humans can vary as much as the variance between mammal neurons and bird neurons, so the smaller human brains probably don't have a large number of small neurons that birds have.

    From the first link:
    "Scientists were left with a generally unsatisfactory fallback position: Avian brains must simply be wired in a completely different fashion from primate brains. Two years ago, even this hypothesis was knocked down by a detailed study of pigeon brains, which concluded that they are, in fact, organized along quite similar lines to those of primates.

    The new study provides a more plausible explanation: Birds can perform these complex behaviors because birds' forebrains contain a lot more neurons than any one had previously thought - as many as in mid-sized primates."
    High neural count (based on broader observations of many species) + low neural density (as seen in comparison between different humans-> which in turn is associated with a more efficient neural structure) seem to be the key to high intelligence.
    I recall that there might be an association between brain size and muscular mass. That'd explain why the Neanderthals had bigger brains (on average) than modern humans without being (necessarily) smarter. Same between men and women. Of course, we can't extrapolate what's observed in birds to humans because the latter are mammals, and their brains are wired differently. Then you have the example of marine mammals: their brains are also big when compared to those of humans, but it seems that echolocation takes a lot of brain power, so they're not necessarily smarter...

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    Quote Originally Posted by Milkyway View Post
    I recall that there might be an association between brain size and muscular mass. That'd explain why the Neanderthals had bigger brains (on average) than modern humans without being (necessarily) smarter. Same between men and women. Of course, we can't extrapolate what's observed in birds to humans because the latter are mammals, and their brains are wired differently. Then you have the example of marine mammals: their brains are also big when compared to those of humans, but it seems that echolocation takes a lot of brain power, so they're not necessarily smarter...
    Well yes you also need a bigger brain to manage a more voluminous/larger body. Which is why raw brain size doesn't tell you much (but it still has a small positive correlation regardless of all of the other factors that influence brain size). The point is, pretty much everything that I have seen (including the links presented in this thread) affirm that neural count (do not conflate this with glial cell count) and neural arrangement (aided with lower density at least in humans) have a positive correlation with intelligence.

    As for raw size- as said earlier: non-neurons do add on to that, and as you have just mentioned- a larger body size would need to be accounted for as well. So, say you have person A and person B both with a ~1600 gram brain (and equal cranial capacity) with an equal number of total neurons and glial cells- if person A is significantly smaller (in body size) than person B, then you would expect person A to probably be smarter than person B- though this would assume that person B doesn't have a significantly better neural arrangement to make up for the extra size disadvantage (or maybe even go so far as to make B smarter than A).

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