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Comment by jiggawatts | Hacker News Reader

This is also why brain mass is roughly proportional to body mass, but not very proportional to general intelligence. A blue whale has a 7kg brain, about 5x the size of the typical human brain, but doesn't appear to have even human-level intelligence let alone 5x super-human intelligence.

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It's better to compare the weight using brain/body^(2/3) than using body/body directly. With that correction most of the paradox disappear. More info in https://en.wikipedia.org/wiki/Encephalization_quotient

From understanding never density in mammals is mostly the same. So large body mass means more nerves that have to communicate with central nervous system.

Also some people have argued that fish can't feel pain or are less sensitive to due to their lower nerve density from my understanding. A whale is a mammal so I would assume it's going to have similar nerve density. Which means the brain has to be able to take input from a larger volume of body so that brain in large animals would make sense to be larger.

SSC had an interesting post on the EQ: https://slatestarcodex.com/2019/03/25/neurons-and-intelligen...

The brain size comparison and its relationship to body mass is super interesting.

The intelligence comparison is a little bit too simplistic though. How do you define intelligence? Are we humans really "more intelligent" than whales? There are a lot of human behaviors that are not intelligent at all, and which seem to be a lot less intelligent than what whales do (and pretty much any other animal on the planet for that matter).

Such as?

Such as war and indiscriminate destruction of our environment

What makes this https://en.wikipedia.org/wiki/Gombe_Chimpanzee_War different from human war? And other species certainly do destroy their environments https://en.wikipedia.org/wiki/Invasive_species it's just that we don't consider them morally culpable.

Great links and examples, very good point. Which brings us back to the original point: are humans actually more intelligent than animals? I don't think so. It's a human self-aggrandizing illusion to believe we are somehow "better" in any way to animals.

Does a whale have more muscles to control than a human? Is its environment more complex to navigate - swimming through water vs balancing , walking running and jumping? Does it have more bones making its body more complex to maneuver? Are its eyes larger with many more rods and cones, looking at a more complex environment and requiring greater neuron counts to interpret?

I think the answer to most (though not all) of these questions is no. Just because a body is bigger doesn't necessarily make it more complex to control surely? For the most part large mammals have the same number of muscles and bones as a small one, and past a certain body size eyes don't get particularly larger.

I seem to recall that even very large dinosaurs could have comparatively tiny brains compared to mammals - did they control their bodies clumsily and observe the world much less acutely than mammals?

So I have always found this explanation a bit suspect - it is a "just so" story because we observe that whales and elephants don't seem all that smart yet they have bigger brains and bodies but that doesn't make the explanation true by itself. Has there been any actual research that supports the hypothesis that large bodies require bigger brains to control?

The brain volume largely correlates to body size [0] in mammals. More muscle cells require more nerves to control them which requires more coordination and hence a larger brain.

How the mammalian brain divies up this process depends on enviromental factors and the body plan. Dolphins and whales have specific parts of the brain used for ecolocation and the water pressure affects the volume of the brain. Elephants have larger areas devoted to using their trunk. Aye-Ayes have large visual cortices as they hunt inscets in the dark for food.

[0] https://en.wikipedia.org/wiki/Brain_size

Hmmh, but a whale's sensori-motor skills are quite rudimentary compared to a human's. A human can manipulate objects, walk, run, dance, swim, jump. A whale can only swim and maybe do a fairly restricted set of dives?

Have a look at dolphins playing with bubble rings - https://www.youtube.com/watch?v=bT-fctr32pE - and making labyrinths out of suspended mud to catch fish with - https://www.youtube.com/watch?v=bzfqPQm-ThU

We are talking about Whales not dolphins. Dolphins have always been the subject of researches for their higher than average intelligence.

Don't forget that pretty much every part of your's and a whales body has nerves in it to detect pain & contract muscles.

More body mass means more nerves that need to send and receive information from the central nervous system.

So even assuming a constant amount nerve endings in cm^3 of flesh between whales and humans a whale will have significantly more.

Whales can do the DSP for sonar, humans can’t.

there are blind people who can use essentially echo location to get an idea of their surroundings.

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