To support this claim, Neanderthals had bigger brains than we do. However, their skulls don't have crenellations like ours (which means that their cerebellums weren't as complex).
All I'm saying is eating meat helps with brain development. In that it increases brain to body mass index growth. And we were already equipped with omnivorous dentition, hunting was not a complete revolution.
Brains are expensive, and are one possible adaptation. Being able to run really fast is another (cheetahs). Each predator has their specialty, and that specialty allows them to claim a particular part of the available ecological domain. Based on the current writings, our ancestors were forced out of the jungle into savannah by changing climate. They would have been a niche scavenger, as there were already predators holding all the major domains. I think it's probable that bipedalism, tool use, and brains all worked together in a positive-reinforcement spiral. Protohumans had to stand up entirely or go to all fours entirely, because the chimp-like knuckle-walking is very inefficient for long distances. Those who went towards bipedalism discovered that they had a couple of available paws for other tasks. The smarter ones figure out tools or weapons, which makes them better providers, which rachets up the smarts, which are only maximally useful if you're really good bipedally and dexterous, etc etc etc. Like the peacock's tail or the moose's antlers, once a feedback loop gets started, it will only stop when the costs start to exceed the benefits. In the topological landscape of possible solutions to our ouster from the forests, the current reality is only one valley. But it's the one we evolved into. I kind of like it.
Well, I'm not making it up. I'm not that smart. It is, however, one of the theories being bounced around right now amongst the people who do it for a living.
But the bigger brain thing doesn't explain how we became so smart. I googled "why are humans so smart?" and a nice little TED talk came up.
I didn't say you were. Is there a chance that you misunderstood it? It feels like there is a piece that I'm missing.
Neanderthals turn out to be everywhere in Europe pretty much. http://www.sci-news.com/othersciences/anthropology/sima-de-los-huesos-hominins-early-neanderthals-03703.html.
