If you’ve begun to eat like Stone-Age man, believing that our collective dietary habits went horribly astray with the invention of modern agriculture, you might want to make sure you know exactly how our ancient ancestors actually ate. Because otherwise you’re just living in a happy, little fantasy world.
Marlene Zuk, an evolutionary biologist, has written an entire book devoted to the real life of cavemen, and specifically, her take on what she sees as the fantasies that the creators of Paleolithic diets have told themselves to justify their meat-based diets.
Her primary claim seems to be that the ten thousand years that have passed since the invention of modern agriculture have been long enough for humans to evolve the necessary digestive resources to handle wheat, dairy, nightshades, and other food sources that were unknown to our early ancestors.
She backs up these claims with examples of rapid evolution, both in the animal kingdom and in ourselves. After all, the ability for adults to digest milk has been a very late addition to our intestinal arsenal, arising in as little as 7,000 years.
Having said that, the majority of her examples of rapid evolution seem to involve mortal threats, which would by necessity create a stronger evolutionary push than simple digestion-related discomfort. After all, your ancient ancestral grandfather (like all creatures) evolved by producing more children that survived to reproductive age than his competitors. It could very well be that the development of agriculture helped this man survive, while simultaneously causing him great physical distress. Especially if the alternative was starving to death.
I imagine that if Irritable Bowel Syndrome were an immediate death sentence, it would have been selected out of the population long ago. That doesn’t mean that the people who suffer from it today couldn’t be helped by a change in diet.
But her points are well taken, especially when she rails against the sillier claims made by paleo enthusiasts. For example, if you have decided not to wear eye glasses because cavemen had no optometrists, you are probably on the wrong side of evolution regardless of your diet. Especially if you drive a car.
Here’s an article about her: http://www.salon.com/2013/03/10/paleofantasy_stone_age_delusions/
And here’s her book: