Eating animals has been part of our existence as humans and pre-humans for a very long time, probably for at least 5-6 million years. Primate evolution preceded ours by about 60 million years, and during that time period, the size of the primate brain stayed essentially constant at around 350cc, with some variation among species depending on body size. This research means that 60 million years of eating fruit and leaves didn’t result in a bigger brain for our primate predecessors.
