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Care to explain e.g. the difference in size with men having larger brains on average? (between 8% and 13% larger) https://en.wikipedia.org/wiki/Neuroscience_of

Care to explain e.g. the difference in size with men having larger brains on average? (between 8% and 13% larger) https://en.wikipedia.org/wiki/Neuroscience_of_sex_differences https://en.wikipedia.org/wiki/Neuroscience_of_sex_difference...

yjftsjthsd-h 7y ago
Going to actual citation in that article, "Males have on average larger overall absolute volumes (i.e. not corrected for body size) in each volume category (see Table 3), ranging from 8% to 13% larger volume in males." ... aren't males generally physically larger overall? Granted, 8-13% feels like it's disproportionate, but I'd want to check that before drawing any conclusions.
- bluGill 7y ago
  Is correcting for body size correct? If it takes X mass of brain to run the human body, than the larger brain has more cells free to do something other than run the body. Or in other words, how much of a larger brain is required to run a larger body - if the scale isn't linear then I'd expect the larger brain to be "smarter" As the other posters have said, size doesn't seem to correlate to anything. More than that I don't know.
  - yjftsjthsd-h 7y ago
    That's a fair question. I'm given to understand that brain size doesn't directly scale with intelligence (consider sperm whale vs dolphin vs human), but for all I know that's only true between species? Actually now that I'm thinking about it, I'm pretty sure there are pathologies where the brain is too big, but one shouldn't conclude much on pathological cases. So.... I dunno. Maybe?
    - Nasrudith 7y ago
      Anyway one complication between species is we know that brains are composed and are laid out differently which affects density and distribution. Cephalopods for instance lack mylenation and appear to have their brain functions a bit more distributes to the point that they occasionally have "rogue arms" which act dysfunctional to the point the host decides to just chew it off and eventually regenerate a "sane" replacement.
  - Nasrudith 7y ago
    It is probably a very rough approximation anyway as it doesn't account for what a given body is. A brain the size of a gnat would be insufficient to handle a body the size of an elephant but that doesn't say how relevant the difference is even in the same order of magnitude. A morbid observation of hunters and tanners is that anything the brain of anything they skin is enough to tan its hide. Now that is clearly a chemical process with a very remote relation to actual processing capability given that tanin can subsitute for tanning but not thinking but it does hint at a lower bound size constraint for even the dumbest vertabrate. That aside the point is there would be less nerve input for the brain to process from five grams of fat, five grams of skin, or say an organ like the eye. Let alone any other other details it must acount or provide for. Further complicating things is neural plasticity - if I recall correctly "optical" areas of the born blind tend to be repurposed for other senses as opposed to say mathematical ability. TL;DR: There is evidence but certainly not good enough to tell us anything about sex differences in humans.
  - dmichulke 7y ago
    Not exactly the same but: https://en.wikipedia.org/wiki/Brain-to-body_mass_ratio https://en.wikipedia.org/wiki/Brain-to-body_mass_ratio
gcthomas 7y ago
Brain size doesn't correlate very well with intelligence amongst humans, while average brain differences between men and women are both nuanced and not universal.
- dmichulke 7y ago
  I know but that doesn't answer the question how culture makes male brains bigger which is the statement of OP
  - gcthomas 7y ago
    Men have bigger brains most likely because they have bigger bodies. Bigger bodies need bigger brains to control them. But there are differences in the relative proportions of grey vs white matter for example, so in this case size most likely doesn't matter.
- yorwba 7y ago
  It does however mean that the GP's Every time sexists come out with "brain differences", we find they are culture differences. is factually wrong (unless you can somehow explain brain size culturally). A better argument would be that every time brain differences were found, they turn out to be irrelevant. However, I'm not sure even that is true, considering some colleges are experimenting with mental rotation training to help female engineering students, with good results: https://www.kqed.org/mindshift/43802/can-teaching-spatial-skills-help-bridge-the-stem-gender-gap https://www.kqed.org/mindshift/43802/can-teaching-spatial-sk... That example also shows identifying gender differences is not a bad thing; it allows coming up with ways to compensate.
  - gcthomas 7y ago
    Women's bodies _are_ different from men's in a number of ways, so it is likely that their brains are different for similar reasons. But brains are very plastic in their functions - you can live quite happily if born with only half a one, for example. But the plasticity means that cultural practises are likely to have an effect on brains, in the same way that London Cabbies famously have over developed hippocampus with more nerve cells than they had before due to the requirements of their jobs. Finding brain differences does not, therefore, mean that the differences are genetic or directly gender related, but could be culturally generated through different roles being adopted for social reasons.
JulianMorrison 7y ago
Same reason men have bigger feet.
YeGoblynQueenne 7y ago
Men have larger body mass on average. For example, the difference is about 10 kg. (20 lb.) in the US: https://en.wikipedia.org/wiki/Human_body_weight#Average_weight_around_the_world https://en.wikipedia.org/wiki/Human_body_weight#Average_weig... It seems pretty clear that absolute brain mass is not that important, but the ratio of brain to body mass, is. For example, whales famously have (much) larger brains than humans, but are not (considered) as intelligent as humans. https://ofwhale.com/how-big-is-a-whales-brain/ https://ofwhale.com/how-big-is-a-whales-brain/ The brain of the sperm whale is the largest, five times heavier than a human’s. The adult sperm whale brain is 8,000 cubic centimeters weighing about 8 kg (18 lb), while ours is about 1300 cubic centimeters. A human brain can weigh 1.5 kg in adulthood. Note again: sperm whales have five times more brains than humans.

yjftsjthsd-h 7y ago

Going to actual citation in that article, "Males have on average larger overall absolute volumes (i.e. not corrected for body size) in each volume category (see Table 3), ranging from 8% to 13% larger volume in males." ... aren't males generally physically larger overall? Granted, 8-13% feels like it's disproportionate, but I'd want to check that before drawing any conclusions.

bluGill 7y ago
Is correcting for body size correct? If it takes X mass of brain to run the human body, than the larger brain has more cells free to do something other than run the body. Or in other words, how much of a larger brain is required to run a larger body - if the scale isn't linear then I'd expect the larger brain to be "smarter" As the other posters have said, size doesn't seem to correlate to anything. More than that I don't know.
- yjftsjthsd-h 7y ago
  That's a fair question. I'm given to understand that brain size doesn't directly scale with intelligence (consider sperm whale vs dolphin vs human), but for all I know that's only true between species? Actually now that I'm thinking about it, I'm pretty sure there are pathologies where the brain is too big, but one shouldn't conclude much on pathological cases. So.... I dunno. Maybe?
  - Nasrudith 7y ago
    Anyway one complication between species is we know that brains are composed and are laid out differently which affects density and distribution. Cephalopods for instance lack mylenation and appear to have their brain functions a bit more distributes to the point that they occasionally have "rogue arms" which act dysfunctional to the point the host decides to just chew it off and eventually regenerate a "sane" replacement.
- Nasrudith 7y ago
  It is probably a very rough approximation anyway as it doesn't account for what a given body is. A brain the size of a gnat would be insufficient to handle a body the size of an elephant but that doesn't say how relevant the difference is even in the same order of magnitude. A morbid observation of hunters and tanners is that anything the brain of anything they skin is enough to tan its hide. Now that is clearly a chemical process with a very remote relation to actual processing capability given that tanin can subsitute for tanning but not thinking but it does hint at a lower bound size constraint for even the dumbest vertabrate. That aside the point is there would be less nerve input for the brain to process from five grams of fat, five grams of skin, or say an organ like the eye. Let alone any other other details it must acount or provide for. Further complicating things is neural plasticity - if I recall correctly "optical" areas of the born blind tend to be repurposed for other senses as opposed to say mathematical ability. TL;DR: There is evidence but certainly not good enough to tell us anything about sex differences in humans.
- dmichulke 7y ago
  Not exactly the same but: https://en.wikipedia.org/wiki/Brain-to-body_mass_ratio https://en.wikipedia.org/wiki/Brain-to-body_mass_ratio

gcthomas 7y ago

Brain size doesn't correlate very well with intelligence amongst humans, while average brain differences between men and women are both nuanced and not universal.

dmichulke 7y ago
I know but that doesn't answer the question how culture makes male brains bigger which is the statement of OP
- gcthomas 7y ago
  Men have bigger brains most likely because they have bigger bodies. Bigger bodies need bigger brains to control them. But there are differences in the relative proportions of grey vs white matter for example, so in this case size most likely doesn't matter.
yorwba 7y ago
It does however mean that the GP's Every time sexists come out with "brain differences", we find they are culture differences. is factually wrong (unless you can somehow explain brain size culturally). A better argument would be that every time brain differences were found, they turn out to be irrelevant. However, I'm not sure even that is true, considering some colleges are experimenting with mental rotation training to help female engineering students, with good results: https://www.kqed.org/mindshift/43802/can-teaching-spatial-skills-help-bridge-the-stem-gender-gap https://www.kqed.org/mindshift/43802/can-teaching-spatial-sk... That example also shows identifying gender differences is not a bad thing; it allows coming up with ways to compensate.
- gcthomas 7y ago
  Women's bodies _are_ different from men's in a number of ways, so it is likely that their brains are different for similar reasons. But brains are very plastic in their functions - you can live quite happily if born with only half a one, for example. But the plasticity means that cultural practises are likely to have an effect on brains, in the same way that London Cabbies famously have over developed hippocampus with more nerve cells than they had before due to the requirements of their jobs. Finding brain differences does not, therefore, mean that the differences are genetic or directly gender related, but could be culturally generated through different roles being adopted for social reasons.

JulianMorrison 7y ago

Same reason men have bigger feet.

YeGoblynQueenne 7y ago

Men have larger body mass on average. For example, the difference is about 10 kg. (20 lb.) in the US: https://en.wikipedia.org/wiki/Human_body_weight#Average_weight_around_the_world https://en.wikipedia.org/wiki/Human_body_weight#Average_weig... It seems pretty clear that absolute brain mass is not that important, but the ratio of brain to body mass, is. For example, whales famously have (much) larger brains than humans, but are not (considered) as intelligent as humans. https://ofwhale.com/how-big-is-a-whales-brain/ https://ofwhale.com/how-big-is-a-whales-brain/ The brain of the sperm whale is the largest, five times heavier than a human’s. The adult sperm whale brain is 8,000 cubic centimeters weighing about 8 kg (18 lb), while ours is about 1300 cubic centimeters. A human brain can weigh 1.5 kg in adulthood. Note again: sperm whales have five times more brains than humans.