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Uff. It is not even a contest: Orcas have the second biggest brains (after Sperm Whales) with a weight of 6-7 kg. White Sharks have a brain of 35 grams. 200 tim

by ralfd 7y ago

Uff. It is not even a contest: Orcas have the second biggest brains (after Sperm Whales) with a weight of 6-7 kg. White Sharks have a brain of 35 grams. 200 times less! https://www.quora.com/What-is-a-very-primitive-brain-like-in-non-human-animals https://www.quora.com/What-is-a-very-primitive-brain-like-in... I thought air (23%) also has more oxygen than water (1%), so Orcas have a big advantage in endurance here, but googling it water is much more dense than air and has more oxygen counted as mass. My guess is, that oxygen is more accessible with breathing air in lungs than with having gills?

samatman 7y ago
You guess correctly. Oxygen "wants to" dissolve in oxygen-depleted water, especially ionic/salty water, specifically blood. It's much less eager to permeate from one liquid into another liquid of comparable salinity. Sharks have an additional disadvantage over bony fishes, in that they must be moving for their gills to work at all.
- Pfhreak 7y ago
  > Sharks have an additional disadvantage over bony fishes, in that they must be moving for their gills to work at all. The name for this is -"obligate ram ventilators" which is a fantastic phrase.
xxxcbbbcbb 7y ago
Are you implying that brain weight has a direct relationship with intelligence? So if someones brain is heavier that means they are more intelligent right?
- dreamcompiler 7y ago
  No. Large differences in brain weight (e.g. factors of 10 or more) can sometimes matter. But weight is just a poor proxy for more important factors: Number of neurons, number of neuronal interconnections, and specialization of brain areas. Within a species, brain weight differences are unimportant. Even between species it's often unimportant. Blue whale brains are 4x as heavy as human brains but the whales have fewer neurons, and most of those neurons are dedicated to audio processing. https://blogs.scientificamerican.com/news-blog/are-whales-smarter-than-we-are/ https://blogs.scientificamerican.com/news-blog/are-whales-sm...
  - darkerside 7y ago
    I'd imagine most of ours are similarly dedicated to visual processing, but that's just a shot in the... dark
- emn13 7y ago
  That effect almost certainly exists, but whether it amounts to anything much at the small relative differences you'd see between members of the same species is much less apparent. And of course, you're sort of implying that this it is absurd to suggest that brain weight explains intelligence; but note that just because there's a correlation between brain mass and intelligence doesn't mean it's the only factor or even major factor. Not that it's trivial to even measure intelligence or that it's even a well-defined concept, but hey. So before you jump to conclusions: there is obviously research on the matter; e.g. you might start here: https://www.scientificamerican.com/article/does-brain-size-matter1/ https://www.scientificamerican.com/article/does-brain-size-m... But while the effects in humans may be small, the difference between 35g and 7kg is... huge, so even if the effect might be imperceptible and in any case likely irrelevant between healthy humans, that's another story at that kind of ratio. Not to mention that I'm going to take a wild stab in the dark and conjecture that metabolic differences may even increase that difference (i.e. the orca's brain may be running hotter, too).
  - seppin 7y ago
    Intelligence is a completely made up construct, by us. So no I don't think there is an comparison to be made.
    - yibg 7y ago
      Maybe human intelligence / IQ rest can be argued to be either incomplete or not a great measure of raw human intelligence, but you can’t seriously be saying all intelligence is made up and subjective. I think it’s pretty clear for example that humans are a bit more intelligent than a gold fish.
      - Rapzid 7y ago
        It's the new woke thing to downplay human intelligence in comparison to other species and AI. So you wouldn't say "Human intelligence is singularly spectacular and bridging the gulf between human and goldfish intelligence would be harder than traveling from one edge of the universe to another". You would say "Human and goldfish are smart at different things. Goldfish are smart at breathing in water and humans are smart at.. being smart".
- stjohnswarts 7y ago
  it's absolutely true between species, along with how developed particular areas are. Within a species with roughly the same relative size and brain area development it is not the case. The poster didn't imply anything else. Scientists tend to condition it with brain to weight ratio as a close correlation to intelligence. It's easy enough to find on the internet if you're interested.

by ralfd 7y ago

samatman 7y ago

You guess correctly. Oxygen "wants to" dissolve in oxygen-depleted water, especially ionic/salty water, specifically blood. It's much less eager to permeate from one liquid into another liquid of comparable salinity. Sharks have an additional disadvantage over bony fishes, in that they must be moving for their gills to work at all.

Pfhreak 7y ago
> Sharks have an additional disadvantage over bony fishes, in that they must be moving for their gills to work at all. The name for this is -"obligate ram ventilators" which is a fantastic phrase.

xxxcbbbcbb 7y ago

Are you implying that brain weight has a direct relationship with intelligence? So if someones brain is heavier that means they are more intelligent right?

dreamcompiler 7y ago
No. Large differences in brain weight (e.g. factors of 10 or more) can sometimes matter. But weight is just a poor proxy for more important factors: Number of neurons, number of neuronal interconnections, and specialization of brain areas. Within a species, brain weight differences are unimportant. Even between species it's often unimportant. Blue whale brains are 4x as heavy as human brains but the whales have fewer neurons, and most of those neurons are dedicated to audio processing. https://blogs.scientificamerican.com/news-blog/are-whales-smarter-than-we-are/ https://blogs.scientificamerican.com/news-blog/are-whales-sm...
- darkerside 7y ago
  I'd imagine most of ours are similarly dedicated to visual processing, but that's just a shot in the... dark
emn13 7y ago
That effect almost certainly exists, but whether it amounts to anything much at the small relative differences you'd see between members of the same species is much less apparent. And of course, you're sort of implying that this it is absurd to suggest that brain weight explains intelligence; but note that just because there's a correlation between brain mass and intelligence doesn't mean it's the only factor or even major factor. Not that it's trivial to even measure intelligence or that it's even a well-defined concept, but hey. So before you jump to conclusions: there is obviously research on the matter; e.g. you might start here: https://www.scientificamerican.com/article/does-brain-size-matter1/ https://www.scientificamerican.com/article/does-brain-size-m... But while the effects in humans may be small, the difference between 35g and 7kg is... huge, so even if the effect might be imperceptible and in any case likely irrelevant between healthy humans, that's another story at that kind of ratio. Not to mention that I'm going to take a wild stab in the dark and conjecture that metabolic differences may even increase that difference (i.e. the orca's brain may be running hotter, too).
- seppin 7y ago
  Intelligence is a completely made up construct, by us. So no I don't think there is an comparison to be made.
  - yibg 7y ago
    Maybe human intelligence / IQ rest can be argued to be either incomplete or not a great measure of raw human intelligence, but you can’t seriously be saying all intelligence is made up and subjective. I think it’s pretty clear for example that humans are a bit more intelligent than a gold fish.
    - Rapzid 7y ago
      It's the new woke thing to downplay human intelligence in comparison to other species and AI. So you wouldn't say "Human intelligence is singularly spectacular and bridging the gulf between human and goldfish intelligence would be harder than traveling from one edge of the universe to another". You would say "Human and goldfish are smart at different things. Goldfish are smart at breathing in water and humans are smart at.. being smart".
stjohnswarts 7y ago
it's absolutely true between species, along with how developed particular areas are. Within a species with roughly the same relative size and brain area development it is not the case. The poster didn't imply anything else. Scientists tend to condition it with brain to weight ratio as a close correlation to intelligence. It's easy enough to find on the internet if you're interested.