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I don't subscribe to New Scientist's trick title or the theories of nutrient limited mammalian brain evolution. Compare brain size of carnivore species with he

I don't subscribe to New Scientist's trick title or the theories of nutrient limited mammalian brain evolution. Compare brain size of carnivore species with herbivores - there is no overt division in average or max brain size. Generally, herbivorous mammals seem to evolve brains just as large as carnivorous ones. Elephants, orangutans, gorillas grow big brains on a vegetarian diet. If predator diets contain a special surplus of evolutionary-brain-growing nutrients, a few predator species should manifest that claim ~ besides our own artful and fire cooking one.

village-idiot 8y ago
Brain size to body size matters a lot too. Sperm whales have about 6x the brain we do, but far more than 6x the body to control.
- strainer 8y ago
  Just looking now.. Mice have similar brain/body-mass ratio as humans. There is no strong (or visible) distinction in brain size between carnivores and herbivores in these comparisons: https://en.wikipedia.org/wiki/Brain-to-body_mass_ratio#Comparisons_between_groups https://en.wikipedia.org/wiki/Brain-to-body_mass_ratio#Compa...
  - gus_massa 8y ago
    You don't have to compare brain-mass/body-mass. You have to compare brain-mass/body-mass^(2/3). > This phenomenon can be described by an equation of the form E = CS^r, where E and S are brain and body weights, r a constant that depends on animal family (but close to 2/3 in many vertebrates
- im3w1l 8y ago
  I know this is the conventional wisdom but it doesn't really make sense. Controlling a sperm whale's body doesn't seem like a hard computational problem.
  - deleted 8y ago
    [deleted]
  - friedman23 8y ago
    I assume you mean relative to controlling a human body?
    - im3w1l 8y ago
      Relative to anything smaller really.
  - mateo1 8y ago
    Echolocation in a "true" 3d environment is a very hard computational problem, which is why many aqueous mammals developed larger brains.
nosianu 8y ago
Look at it this way: FIRST ----- It's not a causal relationship, more energy is available -> brains start growing. There must be evolutionary pressure for brain growth in the first place. Otherwise larger brains are selected against because it's wasteful compared to what the competition does, even if there is more energy. Only if there is such a pressure does the availability of more energy make a difference. Other species put energy surpluses into things like elaborate but useless physiological features (interpreted as signalling their health to potential female mates), such as large tails or feathers that are either useless or sometimes even actually hinder and have no other function (that we found). So just "more energy" does not point towards any specific development, such as brain size. What happens with it, if anything, depends on other factors. If a predator species is doing just fine finding food and mates, no need to grow the brain, no matter how much energy there is. SECOND ------ A huge difference between herbivores and predators is the amount of time they spent on getting food. Herbivores spend pretty much all their time eating. "Meat eaters" spend most of their time resting. The additional energy is used to delay the time between meals. (Herbivore) meat grows a lot slower than plants. Alternatively, there would have to be a lot less predators, and they would have to roam greater distances - which may not work out energy wise when you add it all up. It would be interesting to do some calculations, what happens to energy if you tweak those variables, i.e. a predator species eating significantly more and using the additional energy to sleep less, what are the limitations, what happens to the system, where are the constrains? Humans eat meat and we also spend most of our time doing something (other than eating). Of course, we managed to get more nutrients and more energy by cooking, putting part of our digestion outside our bodies, so it's not limited to "energy dense meat" vs. "grass", we are much more flexible that way.
huffmsa 8y ago
But brain to body size is determined by meat and fat consumption. Gorillas are big primates for their brain size. Chimps eat quite a bit of meat, and are not only generally ranked "smarter", but have a bigger brain for their relative body size.
- strainer 8y ago
  Gracile Chimps (bonobos) eat "fruits, nuts, shoots, stems, pith, leaves, roots, flowers and tubers. Mushrooms are occasionally eaten, and invertebrates such as termites, worms and grubs make up a small proportion of their diet." - their brains are JUST AS BIG as their carnivorous cousin species. So we have a direct comparison between two very closely related great apes that strongly indicates no evolutionary brain growth advantage of carnivorous diet. This theory seems to have a single example of an exceptionally large brained predator to claim that predation enables exceptionally large brains - humans. Humans are omnivores - traders, cookers, testers, diversifiers - some human cultures don't eat any meat - and they don't all have little heads as a result. Ive always liked butter and fatty cuts btw, (from well treated hence healthy livestock) but I'm not buying into this pop-sci that eating extra will feed my brain, or that this is what separates our kind from the dumb herbivores - meat fat feeds almost exclusively my paunch ! :]

village-idiot 8y ago

Brain size to body size matters a lot too. Sperm whales have about 6x the brain we do, but far more than 6x the body to control.

strainer 8y ago
Just looking now.. Mice have similar brain/body-mass ratio as humans. There is no strong (or visible) distinction in brain size between carnivores and herbivores in these comparisons: https://en.wikipedia.org/wiki/Brain-to-body_mass_ratio#Comparisons_between_groups https://en.wikipedia.org/wiki/Brain-to-body_mass_ratio#Compa...
- gus_massa 8y ago
  You don't have to compare brain-mass/body-mass. You have to compare brain-mass/body-mass^(2/3). > This phenomenon can be described by an equation of the form E = CS^r, where E and S are brain and body weights, r a constant that depends on animal family (but close to 2/3 in many vertebrates
im3w1l 8y ago
I know this is the conventional wisdom but it doesn't really make sense. Controlling a sperm whale's body doesn't seem like a hard computational problem.
- deleted 8y ago
  [deleted]
- friedman23 8y ago
  I assume you mean relative to controlling a human body?
  - im3w1l 8y ago
    Relative to anything smaller really.
- mateo1 8y ago
  Echolocation in a "true" 3d environment is a very hard computational problem, which is why many aqueous mammals developed larger brains.

nosianu 8y ago

Look at it this way: FIRST ----- It's not a causal relationship, more energy is available -> brains start growing. There must be evolutionary pressure for brain growth in the first place. Otherwise larger brains are selected against because it's wasteful compared to what the competition does, even if there is more energy. Only if there is such a pressure does the availability of more energy make a difference. Other species put energy surpluses into things like elaborate but useless physiological features (interpreted as signalling their health to potential female mates), such as large tails or feathers that are either useless or sometimes even actually hinder and have no other function (that we found). So just "more energy" does not point towards any specific development, such as brain size. What happens with it, if anything, depends on other factors. If a predator species is doing just fine finding food and mates, no need to grow the brain, no matter how much energy there is. SECOND ------ A huge difference between herbivores and predators is the amount of time they spent on getting food. Herbivores spend pretty much all their time eating. "Meat eaters" spend most of their time resting. The additional energy is used to delay the time between meals. (Herbivore) meat grows a lot slower than plants. Alternatively, there would have to be a lot less predators, and they would have to roam greater distances - which may not work out energy wise when you add it all up. It would be interesting to do some calculations, what happens to energy if you tweak those variables, i.e. a predator species eating significantly more and using the additional energy to sleep less, what are the limitations, what happens to the system, where are the constrains? Humans eat meat and we also spend most of our time doing something (other than eating). Of course, we managed to get more nutrients and more energy by cooking, putting part of our digestion outside our bodies, so it's not limited to "energy dense meat" vs. "grass", we are much more flexible that way.

huffmsa 8y ago

But brain to body size is determined by meat and fat consumption. Gorillas are big primates for their brain size. Chimps eat quite a bit of meat, and are not only generally ranked "smarter", but have a bigger brain for their relative body size.

strainer 8y ago
Gracile Chimps (bonobos) eat "fruits, nuts, shoots, stems, pith, leaves, roots, flowers and tubers. Mushrooms are occasionally eaten, and invertebrates such as termites, worms and grubs make up a small proportion of their diet." - their brains are JUST AS BIG as their carnivorous cousin species. So we have a direct comparison between two very closely related great apes that strongly indicates no evolutionary brain growth advantage of carnivorous diet. This theory seems to have a single example of an exceptionally large brained predator to claim that predation enables exceptionally large brains - humans. Humans are omnivores - traders, cookers, testers, diversifiers - some human cultures don't eat any meat - and they don't all have little heads as a result. Ive always liked butter and fatty cuts btw, (from well treated hence healthy livestock) but I'm not buying into this pop-sci that eating extra will feed my brain, or that this is what separates our kind from the dumb herbivores - meat fat feeds almost exclusively my paunch ! :]