Not the bullshit pseudo-paleo diet that's been a fad in recent years, and it might only be limited to improving your gut flora (which could have big health benefits, though the science is mixed on what exactly that means). A professor of genetic epidemiology recounts the results of eating a true hunter-gatherer diet for three days (which are pretty remarkable, actually). Lots more at the link, as it's a long article, but the gist of it is fairly simple: If you want to ensure that you're healthy, it's probably best to have a very diverse diet, and hunter-gather types eat some 600 different species of plants and animals, while folks in Western-type societies aren't nearly as diverse.