Intelligence isn’t actually all that useful for evolutionary purposes, so there’s no pressing reason for our intelligence to have been optimised.
Comparing humans to all other life forms we know about, I think there’s good evidence that we ARE optimized for intelligence, at least as far as random mutation has so far brought us.
Gah, I had a longish reply written that got eaten when I tried to see my own comment for more context :(
Anyway, the gist of what I was going to say is that tens of thousands of years ago we hit an optimal balance between intelligence and other factors like being able to run for a long time and not having all that much protein in our diet, and it’s only recently (in evolutionary terms) that we’ve stopped needing those other factors. So now there’s a lot more space for optimisation of intelligence.
If the metaphor of “more space” refers to the balance of intelligence and more directly physically useful attributes, and that balance is shifting towards the former, doesn’t that imply that as we get smarter we’ll get less physically fit, or at least no fitter?
If we’re actually selecting for intelligence, then probably yes. But I don’t see a lot of evidence of that happening since guys who are really sporty aren’t exactly selected against in the dating pool.
Actually, now that I think about it it’s probably too flippant to say it’s a direct trade off between running marathons and being smart. It might be something else that gets traded off. Alternatively, the next step might just be for our bodies to adapt to our nigh-unlimited energy intake and start consuming more of it, without anything getting traded. Niche construction theory implies that since we’ve made conditions better for ourselves it’s only a matter of time until we physically adapt to fit the niche more effectively.
the next step might just be for our bodies to adapt to our nigh-unlimited energy intake and start consuming more of it
That’s actually an interesting point. I’m in a biological anthropology class at the moment, and a point that’s been made a few times about human brain evolution is that it uses up a LOT of energy, which definitely was a tradeoff at a time when food input was scarce. (Why this was worth it for us is one of the questions of the field.) It would be neat if first-world humans adapted to the ready supply of food by growing their brains further to use the extra energy. This would, in fact, correspond to an increase in physical fitness, as well as intelligence, because it would help maintain an energy balance.
It’s a flight of fancy, of course, but a fun one.
On a side note, apparently koalas adapted the other way—when they began eating eucalyptus, enabling them to stay in one tree all day instead of roving around searching for food, they needed the brain less and the successful koalas in each generation expended less energy on it. Result: dumber koalas. Still awfully cute though. (I don’t have an academic link about this handy, but this page alludes to their small brains, and the History page mentions that the animal predates the tree. I can probably get a real cite from my anthro teacher if it’s called for. Google image search will serve to cite the cuteness.)
Heh, I’m Australian and so have seen the cuteness many times, and up close :)
I didn’t know they’d gone in that direction though! I learnt that marsupials have basically no brains compared to their placental mammal counterparts but I always assumed that the causation went something like:
Very little food in Australian bush → animals which already had low energy requirements (by being dumb) thrived → no pressure to change because the environment was boring
Let me know if you think you have an answer to the bigger brains question! I recently read a linguistics book about the origins of language, and there was a lot of historical background on our savannah ancestry and how we might have come to need language in the first place. But the author handwaved the brains part completely, just noting that in his scenario where we were scavenging dead mammoths and whatnot, the increased protein and fat would have let us grow bigger brains—nothing about why.
and so have seen the cuteness many times, and up close
I’m jealous. I’m still totally a five-year-old at heart when it comes to fuzzy little mammals.
no pressure to change because the environment was boring
Haha. Well, according to the page I just linked (which I just noticed cites its source as The Koala. Natural History, Conservation & Management. Martin & Handasyde. UNSW Press. 1999. P53), koalas have small brains even among marsupials.
Let me know if you think you have an answer to the bigger brains question!
Don’t hold your breath—I’m not in an anthro program, it just happens to be the science I’m taking (because it’s closer to my area of interest than bio or chem is). However, I can tell you that if you put a ferocious-looking mechanical leopard in chimpanzee territory, upon being “attacked” by the leopard, the chimps will pick up sticks and rocks to throw at it. Way to go, li’l cousins.
Intelligence isn’t actually all that useful for evolutionary purposes, so there’s no pressing reason for our intelligence to have been optimised.
There’s also a large difference between synthesising useful chemicals yourself and taking them in concentrated forms that don’t occur naturally.
Comparing humans to all other life forms we know about, I think there’s good evidence that we ARE optimized for intelligence, at least as far as random mutation has so far brought us.
Gah, I had a longish reply written that got eaten when I tried to see my own comment for more context :(
Anyway, the gist of what I was going to say is that tens of thousands of years ago we hit an optimal balance between intelligence and other factors like being able to run for a long time and not having all that much protein in our diet, and it’s only recently (in evolutionary terms) that we’ve stopped needing those other factors. So now there’s a lot more space for optimisation of intelligence.
If the metaphor of “more space” refers to the balance of intelligence and more directly physically useful attributes, and that balance is shifting towards the former, doesn’t that imply that as we get smarter we’ll get less physically fit, or at least no fitter?
If we’re actually selecting for intelligence, then probably yes. But I don’t see a lot of evidence of that happening since guys who are really sporty aren’t exactly selected against in the dating pool.
Actually, now that I think about it it’s probably too flippant to say it’s a direct trade off between running marathons and being smart. It might be something else that gets traded off. Alternatively, the next step might just be for our bodies to adapt to our nigh-unlimited energy intake and start consuming more of it, without anything getting traded. Niche construction theory implies that since we’ve made conditions better for ourselves it’s only a matter of time until we physically adapt to fit the niche more effectively.
That’s actually an interesting point. I’m in a biological anthropology class at the moment, and a point that’s been made a few times about human brain evolution is that it uses up a LOT of energy, which definitely was a tradeoff at a time when food input was scarce. (Why this was worth it for us is one of the questions of the field.) It would be neat if first-world humans adapted to the ready supply of food by growing their brains further to use the extra energy. This would, in fact, correspond to an increase in physical fitness, as well as intelligence, because it would help maintain an energy balance.
It’s a flight of fancy, of course, but a fun one.
On a side note, apparently koalas adapted the other way—when they began eating eucalyptus, enabling them to stay in one tree all day instead of roving around searching for food, they needed the brain less and the successful koalas in each generation expended less energy on it. Result: dumber koalas. Still awfully cute though. (I don’t have an academic link about this handy, but this page alludes to their small brains, and the History page mentions that the animal predates the tree. I can probably get a real cite from my anthro teacher if it’s called for. Google image search will serve to cite the cuteness.)
Heh, I’m Australian and so have seen the cuteness many times, and up close :)
I didn’t know they’d gone in that direction though! I learnt that marsupials have basically no brains compared to their placental mammal counterparts but I always assumed that the causation went something like:
Very little food in Australian bush → animals which already had low energy requirements (by being dumb) thrived → no pressure to change because the environment was boring
Let me know if you think you have an answer to the bigger brains question! I recently read a linguistics book about the origins of language, and there was a lot of historical background on our savannah ancestry and how we might have come to need language in the first place. But the author handwaved the brains part completely, just noting that in his scenario where we were scavenging dead mammoths and whatnot, the increased protein and fat would have let us grow bigger brains—nothing about why.
I’m jealous. I’m still totally a five-year-old at heart when it comes to fuzzy little mammals.
Haha. Well, according to the page I just linked (which I just noticed cites its source as The Koala. Natural History, Conservation & Management. Martin & Handasyde. UNSW Press. 1999. P53), koalas have small brains even among marsupials.
Don’t hold your breath—I’m not in an anthro program, it just happens to be the science I’m taking (because it’s closer to my area of interest than bio or chem is). However, I can tell you that if you put a ferocious-looking mechanical leopard in chimpanzee territory, upon being “attacked” by the leopard, the chimps will pick up sticks and rocks to throw at it. Way to go, li’l cousins.
Just mammals? I’ve petted an owl. It was softer than a chinchilla.
Good point! A set of fuzzy animals which has a large intersection with mammals.
Wow.
Good point! A set of fuzzy animals which has a large intersection with mammals.