Most basically, because humans are only just on the cusp of general intelligence.
This a point I’ve been thinking about a lot recently—that the time between the evolution of a species whose smartest members crossed the finish line into general intelligence, and today, is a blink of an eye in evolutionary terms, and therefore we should expect to find that we are roughly as stupid as it’s possible to be and still have some of us smart enough to transform the world
This point of view drastically oversimplifies intelligence.
We are not ‘just on the cusp’ of general intelligence—if there was such a cusp it was hundreds of thousands of years ago. We are far far into an exponential expansion of general intelligence, but it has little do with genetics.
Elephants and whales have larger brains than even our brainiest Einsteins—with more neurons and interconnects, yet the typical human is vastly more intelligent than any animal.
And likewise, if Einstein had been a feral child raised by wolves, he would have been mentally retarded in terms of human intelligence.
Neanderthals had larger brains than us—so evolution actually tried that direction, but it ultimately was largely a dead end. We are probably near some asymptotic limit of brain size. In three very separate lineages—elephant, whale and hominid—brains reached a limit around 200 billion neurons or so and then petered out. In the hominid case it actually receded from the Neanderthal peak with homo sapiens having around 100 billion neurons.
Genetics can surely limit maximum obtainable intelligence, but its principally a memetic phenomenon
Elephants and whales have larger brains than even our brainiest Einsteins—with more neurons and interconnects, yet the typical human is vastly more intelligent than any animal.
Yes, because brain size does not equal neuron count; there are scaling laws at play, and not in the whales’/elephants’ favor. On neurons, whales and elephants are much inferior to humans. Since it’s neurons which compute, and not brain volume, the biological aspect is just fine; we would not expect a smaller number of neurons spread over a larger area (so, slower) to be smarter...
In three very separate lineages—elephant, whale and hominid—brains reached a limit around 200 billion neurons or so and then petered out. In the hominid case it actually receded from the Neanderthal peak with homo sapiens having around 100 billion neurons.
Elephants and whales have larger brains than even our brainiest Einsteins—with more neurons and interconnects, yet the typical human is vastly more intelligent than any animal.
Yes, because brain size does not equal neuron count; there are scaling laws at play, and not in the whales’/elephants’ favor.
Yes. - When I said ‘large’, I was talking about size in neurons, not physical size. Physical size, within bounds, is mostly irrelevant. (although it does effect latency of course).
On neurons, whales and elephants are much inferior to humans.
No—they really do have more neurons, ~257 billion in the elephant’s case. 1 (2014)
Since it’s neurons which compute, and not brain volume, the biological aspect is just fine; we would not expect a smaller number of neurons spread over a larger area (so, slower) to be smarter...
According to google, an elephant brain is about 5kg vs a human’s 1.4kg. So we have 51 billion neurons per kg for the elephant vs 75 to 60 per kg for the human. This is by the way, a smaller difference than I would have expected.
The elephant’s brain has a larger cerebellum than us but smaller cortex: about 5 billion neurons vs our 15 billion ish. Interestingly the elephant cortex is also sparser while its cerebellum is denser, perhaps suggesting that we should look at more parameters, such as synapse density as well (because of course there are many tradeoffs in neural micro-circuits).
Anyway the human cortex’s 3x neuron count is a theory for our greater intelligence. But this by itself is insufficient:
the elephant interacts with the world mainly through its trunk which is cerebellum controlled
humans/primates use up a large chunk of their cortex for vision, the elephant much less so
humans rely far more on their cortex for motor control, such that humans completely lacking a cerebellum are largely functional
Now—is having a larger cortex better for general intelligence than a larger cerebellum? - most likely. It appears to be a better hardware platform for unsupervised learning.
But again the key to intelligence is software—we are smart because of our ability to accumulate mental programs , exchange them, and pass them on to later generations. Our brain is unique mainly in that it was the first general platform for language, not because our brains are larger or have some special secret circuit sauce. (which wouldn’t make sense anyway—humans are recent and breed slowly; the key low level circuit developments were already made many millions of years back in faster breeding ancestor lineages)
Cite for the 200b and 100b neuron claims?
See above for elephant neuron counts.
For humans I was probably just using wikipedia or this page based on older research.
I think jacob_cannell is correct in that whales and elephants have larger brains, but that he’s extrapolating incorrectly when he implies through the conjunction that larger brain size == more neurons and more interconnects; so I’m agreeing with the first part, but pointing out why the second does not logically follow and providing cites that density decreases with brain size & known neuron counts are lower than humans.
I don’t always take the time to cite refs, but I should have been more clear I was talking about elephant and whale brains as being larger in neuron counts.
“We are probably near some asymptotic limit of brain size. In three very separate lineages—elephant, whale and hominid—brains reached a limit around 200 billion neurons or so and then petered out.”
Ever since early tool use and proto-language, scaling up the brain was advantageous for our hominid ancestors, and it in some sense even overscaled, such that we have birthing issues.
For big animals like elephants and whales especially, the costs for larger brains are very low. So the key question is then why aren’t their brains bigger? Trillions of neurons would have almost no extra cost for a 100 ton monster like a blue whale, which is already the size of a hippo at birth.
But instead a blue whale just has order 10^11 neurons, just like us or elephants, even though its brain only amounts to a minuscule 0.007% of its mass. The reasonable explanation: there is no advantage to further scaling—perhaps latency? Or more likely, that there are limits of what you can do with one set of largely serial IO interfaces. These are quick theories—I’m not claiming to know why—just that its interesting.
This point of view drastically oversimplifies intelligence.
We are not ‘just on the cusp’ of general intelligence—if there was such a cusp it was hundreds of thousands of years ago. We are far far into an exponential expansion of general intelligence, but it has little do with genetics.
Elephants and whales have larger brains than even our brainiest Einsteins—with more neurons and interconnects, yet the typical human is vastly more intelligent than any animal.
And likewise, if Einstein had been a feral child raised by wolves, he would have been mentally retarded in terms of human intelligence.
Neanderthals had larger brains than us—so evolution actually tried that direction, but it ultimately was largely a dead end. We are probably near some asymptotic limit of brain size. In three very separate lineages—elephant, whale and hominid—brains reached a limit around 200 billion neurons or so and then petered out. In the hominid case it actually receded from the Neanderthal peak with homo sapiens having around 100 billion neurons.
Genetics can surely limit maximum obtainable intelligence, but its principally a memetic phenomenon
Yes, because brain size does not equal neuron count; there are scaling laws at play, and not in the whales’/elephants’ favor. On neurons, whales and elephants are much inferior to humans. Since it’s neurons which compute, and not brain volume, the biological aspect is just fine; we would not expect a smaller number of neurons spread over a larger area (so, slower) to be smarter...
See https://pdf.yt/d/aF9jcFwWGn6c6I7O / https://www.dropbox.com/s/f9uc6eai9eaazko/1954-tower.pdf , http://changizi.com/diameter.pdf , http://onlinelibrary.wiley.com/doi/10.1002/ar.20404/full , http://www.pnas.org/content/early/2012/06/19/1201895109.full.pdf , https://en.wikipedia.org/wiki/List_of_animals_by_number_of_neurons#Whole_nervous_system
Cite for the 200b and 100b neuron claims? My understanding too was that H. sapiens is now thought to have more like 86b neurons & the 100b figure was a myth ( http://revistapesquisa.fapesp.br/en/2012/02/23/n%C3%BAmeros-em-revis%C3%A3o-3/ ), which indicates the imprecision even for creatures which are still around and easy to study...
Yes. - When I said ‘large’, I was talking about size in neurons, not physical size. Physical size, within bounds, is mostly irrelevant. (although it does effect latency of course).
No—they really do have more neurons, ~257 billion in the elephant’s case. 1 (2014)
According to google, an elephant brain is about 5kg vs a human’s 1.4kg. So we have 51 billion neurons per kg for the elephant vs 75 to 60 per kg for the human. This is by the way, a smaller difference than I would have expected.
The elephant’s brain has a larger cerebellum than us but smaller cortex: about 5 billion neurons vs our 15 billion ish. Interestingly the elephant cortex is also sparser while its cerebellum is denser, perhaps suggesting that we should look at more parameters, such as synapse density as well (because of course there are many tradeoffs in neural micro-circuits).
Anyway the human cortex’s 3x neuron count is a theory for our greater intelligence. But this by itself is insufficient:
the elephant interacts with the world mainly through its trunk which is cerebellum controlled
humans/primates use up a large chunk of their cortex for vision, the elephant much less so
humans rely far more on their cortex for motor control, such that humans completely lacking a cerebellum are largely functional
Now—is having a larger cortex better for general intelligence than a larger cerebellum? - most likely. It appears to be a better hardware platform for unsupervised learning.
But again the key to intelligence is software—we are smart because of our ability to accumulate mental programs , exchange them, and pass them on to later generations. Our brain is unique mainly in that it was the first general platform for language, not because our brains are larger or have some special secret circuit sauce. (which wouldn’t make sense anyway—humans are recent and breed slowly; the key low level circuit developments were already made many millions of years back in faster breeding ancestor lineages)
For humans I was probably just using wikipedia or this page based on older research.
[emphasis added]
Wait, what?
I think jacob_cannell is correct in that whales and elephants have larger brains, but that he’s extrapolating incorrectly when he implies through the conjunction that larger brain size == more neurons and more interconnects; so I’m agreeing with the first part, but pointing out why the second does not logically follow and providing cites that density decreases with brain size & known neuron counts are lower than humans.
I don’t always take the time to cite refs, but I should have been more clear I was talking about elephant and whale brains as being larger in neuron counts.
“We are probably near some asymptotic limit of brain size. In three very separate lineages—elephant, whale and hominid—brains reached a limit around 200 billion neurons or so and then petered out.”
Ever since early tool use and proto-language, scaling up the brain was advantageous for our hominid ancestors, and it in some sense even overscaled, such that we have birthing issues.
For big animals like elephants and whales especially, the costs for larger brains are very low. So the key question is then why aren’t their brains bigger? Trillions of neurons would have almost no extra cost for a 100 ton monster like a blue whale, which is already the size of a hippo at birth.
But instead a blue whale just has order 10^11 neurons, just like us or elephants, even though its brain only amounts to a minuscule 0.007% of its mass. The reasonable explanation: there is no advantage to further scaling—perhaps latency? Or more likely, that there are limits of what you can do with one set of largely serial IO interfaces. These are quick theories—I’m not claiming to know why—just that its interesting.