I got a kick out of a recent NY Times piece that described some modern "cavemen" living in NYC. This tribe of mostly young, white-collar dudes has made a pretty serious hobby out of trying to expose their bodies to the same stresses that our ancestors regularly encountered. They enjoy fasting, intense bouts of aerobic exercise and gorging on organ meat. They also regularly give blood (to further simulate the hunt) and like to run barefoot - all while living in one of the most intensely urban and "unnatural" settlements humans have ever produced.
Underlying their philosophy is the concept that our bodies are best adapted to an ancient hunter-gatherer lifestyle and (implicitly to many) our current way of life is making us sick and unhappy. This has been a contentious idea for generations, with plenty of big shots weighing in (Stephen J. Gould thought modern humans are mismatched to their environment).
In The Evolutionary Search for our Perfect Past, Zuk dismisses this idea that we all would be healthier and happier if we weren't stuck behind our computers eating bread all day as a "paleofantasy."
In The 10,000 Year Explosion, Cochran and Harpending argue that the intense selective pressures of civilization caused remarkable bursts in human evolution. Lactose tolerance was the secret weapon of the Mongols and other nomads, who spread this trait each time they ransacked a village, and who evaporated into the steppe (surviving on milk, meat and blood) until avenging imperial forces exhausted their cereal supplies. They also assert that generations of inbreeding and relegation to the "dirty" book keeping jobs of the Middle Ages made the Ashkenazi Jews super smart.
In On Deep History and the Brain, Smail reconciles these ideas to some extent as he explores how closely biology and culture are entwined, suggesting that the development of our brains and bodies may be more plastic to our environment than we realize - and that many explanations of adaptation simply amount to just-so stories. For example, although pop psychologists like to suggest that men are only attracted to young (fertile) women, and women are only attracted to older (rich and supportive) men, modern hunter-gatherers don't fit this pattern. Besides, the typical hunter-gatherer child gets almost all his calories from his mom's gathering and when his dad does have a successful hunt, the meat is usually distributed evenly among the tribe - with any extra usually going to the man's girlfriend instead of his wife. Likewise, women don't rely on the husband for help with child care - that's what her family and boyfriend are for...
Well, if nothing else, I'm sure good food and exercise won't ever be maladaptive!