| Fun idea. I find that rather unlikely. Some points. Are there any evidence for a period without meat in the diet, to start with? Considering that teeth are hardy, this will probably be testable in our lifetime. I've rather seen claims that the brains were larger before civilization, following the hypothesis that it is hard to live as a hunter gatherer. (And then it was with lots of meat in the diet.) We do know that calories have been a limiting factor for most life, generally also including humans. iirc, 20% of the energy need goes to the brain. The brain size would vary a lot, if it really didn't make a big difference. Consider that the evolved tendencies for getting diabetes are there because it made it easier to handle periods of hunger. So sure, that might be much later, but... And also, eating those starches needed cooking for humans, afaik? Which needs some brain power (there was not time to evolve instincts). We lost a lot in the jaws and teeth to get the brains. (Couldn't have both.) Then, there was news just a week or two ago about a new result -- humans put "building capital" into our brains rather than our muscles, which is why most monkeys while large as children can tear a human's arm off and beat our head in with it... Brains are expensive. I might add that there have to be a hard evolutionary pressure to build complex organs, like the extra stuff in the human brain. It is hardly just more neurons added to earlier monkeys (evolution is hill climbing, so you will find simpler/different analogues in other primates, but it isn't just adding some volume and e.g. <miracle> language circuits :-) ). And so on. This list could probably be longer. :-) |