If all we wanted was to triple human brain size just like Nature can, we’d be breeding more whales. And if tripling brain size inherently tripled intelligence, we’d be asking the whales for their opinions afterwards.
If increasing brain size instead merely provides enough raw matter for other changes to eventually mold into improved intelligence, then it doesn’t just matter how hard the size increase is, it also matters how hard the other changes are. And at least in nature’s case, I reiterate that the improvement process was several orders of magnitude harder than the one-brain process. We might be able to do better than nature, but then we’re no longer talking about “it was easy in nature, so it will be easy for us too”, we’re talking about “it was hard in nature, so it might be hard for us too”.
Nature does seem to be able to scale brains down without the millions of years of evolution it took to scale them up, but that at least makes perfect sense as a pre-evolved characteristic. Accidents and poor nutrition are ubiquitous, so there’s a clear selection pressure for brains to develop to be robust enough that restricted growth or damage can still leave a functional result. Is there any similarly strong evolutionary pressure for brains to develop in such a way that opportunities for increased growth produce a better-functional result? If so it may not have been enough pressure; supernormal growth opportunities do seem to exist but aren’t necessarily positive.
And at least in nature’s case, I reiterate that the improvement process was several orders of magnitude harder than the one-brain process.
If we take “time” as a proxy for “difficulty” we have:
Origin of life: 3500 MYA.
Origin of brains: 600 MYA.
Origin of chimp-human split: 7 MYA.
According to those figures, scaling brains up a few thousand times was much easier than making one in the first place. Scaling one up by a factor of 3 was much, much easier.
As for modern big human brains, the main examples I know of arise from giantism and head binding.
If all we wanted was to triple human brain size just like Nature can, we’d be breeding more whales. And if tripling brain size inherently tripled intelligence, we’d be asking the whales for their opinions afterwards.
If increasing brain size instead merely provides enough raw matter for other changes to eventually mold into improved intelligence, then it doesn’t just matter how hard the size increase is, it also matters how hard the other changes are. And at least in nature’s case, I reiterate that the improvement process was several orders of magnitude harder than the one-brain process. We might be able to do better than nature, but then we’re no longer talking about “it was easy in nature, so it will be easy for us too”, we’re talking about “it was hard in nature, so it might be hard for us too”.
Nature does seem to be able to scale brains down without the millions of years of evolution it took to scale them up, but that at least makes perfect sense as a pre-evolved characteristic. Accidents and poor nutrition are ubiquitous, so there’s a clear selection pressure for brains to develop to be robust enough that restricted growth or damage can still leave a functional result. Is there any similarly strong evolutionary pressure for brains to develop in such a way that opportunities for increased growth produce a better-functional result? If so it may not have been enough pressure; supernormal growth opportunities do seem to exist but aren’t necessarily positive.
(edited to fix broken link)
If we take “time” as a proxy for “difficulty” we have:
Origin of life: 3500 MYA.
Origin of brains: 600 MYA.
Origin of chimp-human split: 7 MYA.
According to those figures, scaling brains up a few thousand times was much easier than making one in the first place. Scaling one up by a factor of 3 was much, much easier.
As for modern big human brains, the main examples I know of arise from giantism and head binding.