An argument against orcas being more intelligent than humans runs thus: Orcas are much bigger than humans, so the fraction of the metabolic cost the brain consumes is smaller than in humans. Thus it took more selection pressure for humans to evolve having 21billion neurons than for orcas to have 43billion.[1] Thus humans might have other intelligence-increasing mutations that orcas didn’t evolve yet.
So the question here is “how much does scale matter vs other adaptations”. Luckily, we can get some evidence on that by looking at other species and rating how intelligent they are and correlating that with (1) number of cortical neurons and (2) fraction of metabolic cost the brain uses, to see how strong of an indicator each is for intelligence.
I have two friends who are looking into this for a few hours on the side (where one tries to find cortical neurons and metabolic cost data, and the other looks at animal behavior to rate intelligence (without knowing about neuron count or so)). It’ll be rather a crappy estimate but hopefully we at least have some evidence from this in a week.
Of course metabolic cost doesn’t necessarily need to be linear in the number of cortical neurons, but it’d be my default guess, and in any case I don’t think it matters for gathering evidence across other species as long as we can directly get data on the fraction of the metabolic cost the brain uses (rather than estimating it through neuron count).
EDIT: I was a bit hasty and phrased this wrong, I didn’t mean to suggest roundtrip is quadratic in length. The max roundtrip time is twice the diameter.
The density of neurons matters a lot. A larger brain means it takes longer for signals to propagate. If the brain is 2x larger, it takes 4x longer for a two way communication. This is a large constraint in both biological brains and GPU design.
Thanks for pointing that out! I will tell my friends to make sure they actually get good data for the metabolic cost and not just use cortical neuron count as proxy if they cannot find something good.
(Or is there also another point you wanted to make?) And yeah it’s actually also an argument for why orcas might be less intelligent (if they sorta use their neurons less often). Thanks.
Actually out of curiosity, why 4x? (And what exactly do you mean by “2x larger”?) (And is this for a naive algorithm which can be improved upon or a tight constraint?)
Sorry i phrased this wrong. You are right. I meant roundtrip time which is twice the length but scales linearly not quadratically.
I actually ran the debate contest to get to the bottom of Jake Cannells arguments. Some of the argument, especially around the landauer argument dont hold up but i think it s important not to throw out the baby with bathwater. I think most of the analysis holds up.
Yeah I read that prize contest post, that was much of where I got my impression of the “consensus”. It didn’t really describe which parts you still considered valuable. I’d be curious to know which they are? My understanding was that most of the conclusions made in that post were downstream of the Landauer limit argument.
My guess is that there probably aren’t a lot of simple mutations which just increase intelligence without increasing cortical neuron count. (Though probably simple mutations can shift the balance between different sub-dimensions of intelligence as constrained through cortical neuron count.) (Also of course any particular species has a lot of deleterious mutations going around and getting rid of those may often just increase intelligence, but I’m talking about intelligence-increasing changes to the base genome.)
But there could be complex adaptations that are very important for abstract reasoning. Metacognition and language are the main ones that come to mind.
So even if the experiment my friends to will show that the number of cortical neurons is a strong indicator, it could still be that humans were just one of the rare cases which evolved a relevant complex adaptation. But it would be significant evidence for orcas being smarter.
An argument against orcas being more intelligent than humans runs thus: Orcas are much bigger than humans, so the fraction of the metabolic cost the brain consumes is smaller than in humans. Thus it took more selection pressure for humans to evolve having 21billion neurons than for orcas to have 43billion.[1] Thus humans might have other intelligence-increasing mutations that orcas didn’t evolve yet.
So the question here is “how much does scale matter vs other adaptations”. Luckily, we can get some evidence on that by looking at other species and rating how intelligent they are and correlating that with (1) number of cortical neurons and (2) fraction of metabolic cost the brain uses, to see how strong of an indicator each is for intelligence.
I have two friends who are looking into this for a few hours on the side (where one tries to find cortical neurons and metabolic cost data, and the other looks at animal behavior to rate intelligence (without knowing about neuron count or so)). It’ll be rather a crappy estimate but hopefully we at least have some evidence from this in a week.
Of course metabolic cost doesn’t necessarily need to be linear in the number of cortical neurons, but it’d be my default guess, and in any case I don’t think it matters for gathering evidence across other species as long as we can directly get data on the fraction of the metabolic cost the brain uses (rather than estimating it through neuron count).
EDIT: I was a bit hasty and phrased this wrong, I didn’t mean to suggest roundtrip is quadratic in length. The max roundtrip time is twice the diameter.
The density of neurons matters a lot. A larger brain means it takes longer for signals to propagate
. If the brain is 2x larger, it takes 4x longer for a two way communication.This is a large constraint in both biological brains and GPU design.Thanks for pointing that out! I will tell my friends to make sure they actually get good data for the metabolic cost and not just use cortical neuron count as proxy if they cannot find something good.
(Or is there also another point you wanted to make?)And yeah it’s actually also an argument for why orcas might be less intelligent (if they sorta use their neurons less often). Thanks.Actually out of curiosity, why 4x? (And what exactly do you mean by “2x larger”?) (And is this for a naive algorithm which can be improved upon or a tight constraint?)
I highly recommend the following sources for a deep dive into these topics and more:
Jacob Cannells’ brain efficiency post https://www.lesswrong.com/posts/xwBuoE9p8GE7RAuhd/brain-efficiency-much-more-than-you-wanted-to-know [thought take the Landauer story with a grain of salt]
and the extraordinary Principles of Neural Design by Sterling & Laughlin https://mitpress.mit.edu/9780262534680/principles-of-neural-design/
Could you explain or directly link to something about the 4x claim? Seems wrong. Communication speed scales with distance not area.
I thought the consensus on that post was that it was mostly bullshit?
Sorry i phrased this wrong. You are right. I meant roundtrip time which is twice the length but scales linearly not quadratically.
I actually ran the debate contest to get to the bottom of Jake Cannells arguments. Some of the argument, especially around the landauer argument dont hold up but i think it s important not to throw out the baby with bathwater. I think most of the analysis holds up.
https://www.lesswrong.com/posts/fm88c8SvXvemk3BhW/brain-efficiency-cannell-prize-contest-award-ceremony
Yeah I read that prize contest post, that was much of where I got my impression of the “consensus”. It didn’t really describe which parts you still considered valuable. I’d be curious to know which they are? My understanding was that most of the conclusions made in that post were downstream of the Landauer limit argument.
My guess is that there probably aren’t a lot of simple mutations which just increase intelligence without increasing cortical neuron count. (Though probably simple mutations can shift the balance between different sub-dimensions of intelligence as constrained through cortical neuron count.) (Also of course any particular species has a lot of deleterious mutations going around and getting rid of those may often just increase intelligence, but I’m talking about intelligence-increasing changes to the base genome.)
But there could be complex adaptations that are very important for abstract reasoning. Metacognition and language are the main ones that come to mind.
So even if the experiment my friends to will show that the number of cortical neurons is a strong indicator, it could still be that humans were just one of the rare cases which evolved a relevant complex adaptation. But it would be significant evidence for orcas being smarter.