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Comment by erikpukinskis | Hacker News Reader

Legit question: if human intelligence is fundamentally limited by scale, why aren’t there some humans running around with heads twice as big and twice the neurons? If it’s such an advantage why hasn’t nature selected for it in at least one place on Earth?

(My answer: above the scale of the human brain there’s diminishing returns on more neurons. Two individuals with their own volition are smarter than one individual with double the brain size. We’ll do a lot of research in AI to find that there aren’t any machine learning problems that can’t be run on a computer about the size and speed of a brain, or distributed among some number of independently operating brain sized computers, and that the problem never was scale but just where to focus)

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Here's my understanding/interpretation - if I get any details wrong, I hope someone will correct me!

Brains are very expensive and, for our body size, we have very large brains; evolution had to build a brain that could operate within the calorie constraints imposed by our ecological niche - presumably a hunter-gatherer niche.

If you graph adult body volume relative to gestation time across the placental mammals, there's a good correlation, but humans are an anomaly; for our body volume we should take more than 9 months. So we are kind of born prematurely - the reason? So our heads can fit through the birth-canal. Significantly bigger brains would have likely entailed altering our walking gate, thus potentially sacrificing our ecological niche (and guaranteed source of those much needed calories!). Most of this was taken from Pinker ([0]).

Bostrom ([1]) brings up another interesting point - anything smarter than us would have probably taken longer to evolve than us. So it might not be inaccurate to think of ourselves as the dumbest species that could build an interplanetary species.

My suspicion is that things much smarter than us are very possible; my reasoning is, it just seems so strange to me that the peak of feasible intelligence just so happens to correspond with what can be fed by a hunter-gatherer diet and fit through a birth-canal which fits into the constraints of an upright primate.

It seems more likely to me that we're a local optimum - we're probably close to the optimal design for something as smart as us, in our ecological niche.

[0] - https://en.wikipedia.org/wiki/How_the_Mind_Works [1] - https://en.wikipedia.org/wiki/Superintelligence:_Paths,_Dang...

>> My suspicion is that things much smarter than us are very possible; my reasoning is, it just seems so strange to me that the peak of feasible intelligence just so happens to correspond with what can be fed by a hunter-gatherer diet and fit through a birth-canal which fits into the constraints of an upright primate.

I think you're understimating the intelligence required to survive as a hunter-gatherer, individual or species, in a world that keeps wanting to kill you, where the number of things that want to make it easy for you to eat them is exactly 0 (not counting fruit, which is made to be eaten by birds, not humans) and the numer of things that want to eat you is ...very big.

If you think about it, the amount of brainpower needed to survive as a primitive human in the savannah is exactly as much as required to develop modern technology. We got were we are today because our ancestors were smart enough to not be eaten by lions etc.

Of course I'm not saying that smarter things than us aren't possible. There's an element of luck involved in evolution. Maybe we 're not the most powerful intelligence that could have evolved on Earth; but we're certainly the one that did.

Very interesting! I happen to know of some other problems: Heat and cross-brain communication time.

Bird brains are much smarter than we are per weight and volume. Not a little bit, but a lot. I think part of the reason they can do that is that they have much better cooling because their heads are small. Having a bigger brain than we do means that it would need to have a lower activity level because of cooling constraints.

There's also diminishing returns from size because the interconnects from one point in the brain to another have longer latency. One response to this is to fold the brain, as we do. Regardless, at some point adding more volume stops making sense.

I read once that bird brains (or some part of them) are more modular and consist of densely connected components - any idea/references about that?

Also, this blog-post (and associated links) may interest you - http://www.rifters.com/crawl/?p=6116

The question isn't whether something could exist that's smarter than every human

The question is whether something could exist that's smarter than every group of humans is

Humans are social, so the social group, and in fact groups of social groups are the highest form of intelligence on the planet. That's the bar to beat, not an individual Homo Sapiens in a observation room.

I think there's a simple explanation for this.

Increased head size == greater risk of death in childbirth

Female hips have already evolved to be as large as possible while still being load-bearing.

It would be interesting to see what the wide-spread use of Caesarean sections would do to the human brain, if we weren't all going to be transhuman within a few generations anyway

As far as whether there are diminishing returns to increased intelligence within one individual, I'd say try taking two people with half of Einstein's IQ and asking them to explain General Relativity

I'm sure there have been individuals throughout time who had normal heads at birth, but whose heads grew more in childhood.

> why aren’t there some humans running around with heads twice as big and twice the neurons?

Because humans don't live in an artificial bubble like ML models do but they always are already entangled in a network (aka society) of similar beings. The ultimate actor isn't the single individual but the group/aggregate/swarm/society. Given the current societal demands, the current brain size is sufficiently large. A single nerd with a double-sized brain would most likely not be able to reproduce in human societies as of today.

We probably shouldn't overrate a single individual's capabilities.

>> Legit question: if human intelligence is fundamentally limited by scale, why aren’t there some humans running around with heads twice as big and twice the neurons? If it’s such an advantage why hasn’t nature selected for it in at least one place on Earth?

There's nothing saying there won't be such humans, one day. Maybe we'll eventually evolve to Homo Sapiens Megacephalus, with brains twice the size than now. Evolution is an ongoing thing, right?

Btw, I don't think it's ever safe to compare machine learning with human intelligence. So far, it's clear that human learning is completely different to machine learning and human learning is only part of human cognition. It's not easy to use observations on the one to draw conclusions about the other.

History seems to suggest precisely the opposite hypothesis; namely that the larger your brain is the more benefit there is from further growth, at least with this line of brain architecture.

http://aquatic-human-ancestor.org/anatomy/images/brain-size....

Does smarter imply more children survive to reproduce?

I think it's more a plus for survival. But society has so much technology and excess resources that this pressure isn't affecting much.

Giant heads have other disadvantages, having to be born being one major one.

With all the problems that big heads carry, human heads have done nothing but grow since our ancestors started walking on two feet.

I guess the only answer available for you is: evolution does not work that fast.

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