If they did have significant additional brain mass, it’s possible it was was used to give them really good instincts instead of the more general purpose circuits we have.
It’s also possible that it did any of a hundred other things. Or that it didn’t strictly do anything itself, but was genetically tied to some other positively selected mutation. Or it was sexually selected. Or it arose without genetic change, from environmental factors, and there wasn’t enough time or pressure for natural selection to remove it again.
Why privilege this hypothesis? Other species that specialize in some way don’t usually grow big brains as a result. In any case the presence of any given physiological adaptation doesn’t imply the absence of intelligence. Modern human intelligence is powerful; any hominid species that happened to evolve it would have a very good chance of using it to spread rapidly. Evolution doesn’t say, “this species is used to relying on physical strength, if an intelligent member is born he just won’t rely on his intelligence”. Every animal is always struggling for survival, no matter how and how well adapted.
I’m not privileging the hypothesis, I’m speculating.
I didn’t mean to start an argument, but I think that you thought because I suggested a hypothesis, you assumed that I took it more seriously than other unspoken hypotheses.
It’s also possible that it did any of a hundred other things. Or that it didn’t strictly do anything itself, but was genetically tied to some other positively selected mutation. Or it was sexually selected. Or it arose without genetic change, from environmental factors, and there wasn’t enough time or pressure for natural selection to remove it again.
Why privilege this hypothesis? Other species that specialize in some way don’t usually grow big brains as a result. In any case the presence of any given physiological adaptation doesn’t imply the absence of intelligence. Modern human intelligence is powerful; any hominid species that happened to evolve it would have a very good chance of using it to spread rapidly. Evolution doesn’t say, “this species is used to relying on physical strength, if an intelligent member is born he just won’t rely on his intelligence”. Every animal is always struggling for survival, no matter how and how well adapted.
I’m not privileging the hypothesis, I’m speculating.
I didn’t mean to start an argument, but I think that you thought because I suggested a hypothesis, you assumed that I took it more seriously than other unspoken hypotheses.