I read an article that documented how along with some of the oldest human remains that were ever discovered there were also scraped bones. If I remember correctly the Australopithecines were all primarily vegetarian, and the scraped bones started showing up at the same time as humans and our big brains started to evolve. Many scientists think it was meat eating that permitted our brains to develop, so I wonder if further development could stop or if we could actually regress if we started denying ourselves these nutrients over a long period of time. Any paleontologists around to tackle this one?