Large-scale agriculture and cooking made us even smarter. A good pot of rice and beans will net you even more energy with less work than meat. It's also less likely to spoil and give you any number of diseases.
Agriculture was (is?) a disaster for our health.
Edit: I noticed that you spoke about increased energy intake and brain size, not just health.
Human brains have shrunk since the establishment of agriculture. Brains are smaller now than during even the middle ages.
Though that paper makes some difficult-to-verify claims.
It might be less a result of the diet's intrinsic problems and more a result of evolutionary pressures favoring dumber people, because work is much easier, so investing in intellect wastes energy that could be spent on other things.
Agriculture paved the road the specialization, and hence the progress, diversity, safety and richness we see in our lives today. We can argue over whether these are virtues or not, but we can't turn our heads from the Darwinian view of life. Living as a nomad, with everybody toiling just to feed the mouths doesn't scale. And, Natural Selection says any group that is able to specialize even a little bit gains strategic advantages over non-specialized groups. No wonder hunters and gatherers were driven to extinction.
Is Jared kidding us when he says that social echelons are bad? I guess, he thinks our hunter-gatherer ancestors treated everybody equally and with respect. I guess 30 seconds in front of Discovery Channel would tell him how apes live - alpha males "ruling" over females, and killing other males over food and right to reproduce. I'm quite amazed at his ability to scorn at social echelons and other malices brought upon us by agriculture while giving a silent nod to killing for food in the same breath!
Especially canning.
But probably not smarter in the way we think of intelligence. They didn't develop civilisation, agriculturalists did.
They didn't make very many durable stone structures. That's about all we know. The complexity and quality of their societies may have generally exceeded ours.
We do know they had transcontinental trading routes and fairly advanced astronomy, in Europe at least.
That's an extremely strong statement. Do you have any proof of significant differences in human intelligence amongst populations?
Basically I'm saying you're full of shit. You should read the book "Guns, Germs, and Steel". It was written by someone who took the time to research the issue and develop some convincing arguments.
"In social psychology, the fundamental attribution error (also known as correspondence bias or attribution effect) describes the tendency to over-value dispositional or personality-based explanations for the observed behaviors of others while under-valuing situational explanations for those behaviors."
Look for it and you see it everywhere.
Of course, the higher human population density means increased likelihood of contagion.
https://secure.wikimedia.org/wikipedia/en/wiki/Origin_of_the...
"Archaeology has placed the earliest known domestication at potentially 30,000 BC, and with certainty at 7,000 BC....Perhaps the earliest clear evidence for this domestication is the first dog found buried together with human [sic] from 12,000 years ago in Israel."
And dogs came with many groups of hunter-gatherers in their intercontinental migrations.