Should You Eat like a Caveman?

Meanwhile, it's likely the gatherer members of the hunter-gatherer community — who tend to get less attention from Paleos, despite having provided up to half of Paleolithic calories — walked up to 9 km (6 mi.) a day, often while weighed down by babies and food. Lieberman says that while our bodies are adapted for a complex combination of endurance and strength, "forty thousand years ago, your average 'caveman' would've been phenomenal at endurance running and terrible at sprinting."

De Vany will have none of that. Speaking in New York City last week after a book signing, the superbly fit 73-year-old, his biceps bulging beneath his orange shirt, called Lieberman's notion "full of crap," pointing to the high rate of injuries among long-distance runners like Alberto Salazar as evidence that such sustained exercise is unnatural. (See Healthland's 5 rules for good health in 2011.)

Robb Wolf, author of The Paleo Solution, earnestly argued at the book signing that ongoing research supports the wisdom of the paleo diet and lifestyle. "We're at the first point in history where we can build this whole argument by molecular biology," Wolf said, citing peer-reviewed studies by Colorado State health and exercise scientist Loren Cordain, author of the popular The Paleo Diet, and the University of Maryland's Alessio Fasano.

The problem, of course, is that even if De Vany and the other paleo believers are right, there's no going back to the world that existed 40,000 years ago. There's not enough fresh game to feed us all, grains and dairy are global dietary staples, and while most folks do not run marathons, sustained runs — or at least long walks — are central to a lot of healthy people's regimens. And our genes don't care how healthy we are as long as we reproduce. "Natural selection is about how many children you have and how many children they have," Lieberman says. "From an adaptation perspective, people today are doing just fine. There are several billion of us." (See the top 10 dieting myths.)

Anyway, to be really Paleolithic, you also have to jettison written language, public sanitation, Jet Blue and representational government.

At the book signing, even John Durant, founder of the lifestyle website Hunter-Gatherer — who joked in a 2010 Colbert Report interview that his "dream woman" is lactose intolerant — conceded the irresistible lure of so simple a modern pleasure as cheese, provided you have the genes for it. "If you want to add a little dairy because you're from Scandinavia," he said, "fine."

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