The paleo diet is being called into question by evolutionary biologist Marlene Zuk.

Marlene Zuk told the Washington Post that the idea is flawed. Zuk is the author of "Paleofantasy: What Evolution Really Tells Us About Sex, Diet and How We Live."

The paleo diet is a modern nutritional plan based on the presumed ancient diet of wild plants and animals that various hominid species habitually consumed during the Paleolithic era-a period of about 2.5 million years, which ended around 10,000 years ago with the development of agriculture and grain-based diets.

"This attitude can be referred to as 'paleo-nostalgia' - the notion that we were all better off before agriculture, or civilization, or the Industrial Revolution," Marlene Zuk told the Post. "It's more helpful and accurate to see that all organisms are constantly evolving. There has been no point in our past when we were perfectly adapted to our environment."

It is based on the idea that human bodies have not adapted sufficiently to eat foods that weren't available 10,000 years ago. The paleo diet focuses on eating meat, fruits and vegetables and avoiding grains and dairy.

"Trying to emulate what people ate 10,000 or 100,000 years ago is really difficult," Zuk told the Post. "Our foods have changed so much that virtually every item in a supermarket is drastically genetically different from its prehistoric equivalent. This is what humans do: We modify foods so that they become more palatable and digestible."

Zuk argued that it is almost impossible also because diets were based on your location. If you lived somewhere, you ate what was accessible to you. He admitted that during the origination of what is known as the paleo diet today, people ate a lot more carbohydrates and starch than expected. Zuk said it is difficult to perfectly mimic the diet of that era.

Another problem deals with milk. "Our genes have changed in the last 10,000 years. Lactase persistence - the ability to digest milk as adults - is the poster child for this," Zuk said. "Our genes have changed extremely rapidly so that at least some populations of humans can digest milk into adulthood."