Dr. Christina Warinner earned her Ph.D. from Harvard University in 2010, specializing in ancient DNA analysis and paleodietary reconstruction. She has done archaeological excavations across the globe, from the Maya jungles of Belize to the Himalayan mountains of Nepal, and she has pioneered the biomolecular investigation of archaeological dental calculus (tartar) to study long-term trends in human health and diet. In this video, she debunks the PaleoDietTM, and any other diet philosophy founded on the claim that humans "evolved to eat meat," or have genetically adapted to meat consumption, or have a physiological need to eat flesh.
At 3:15 she states the bald fact that belies such claims:
"Humans have no known anatomical, physiological, or genetic adaptation to meat consumption."
The only known human genetic and physiological adaptation to animal food consumption consists of lactase persistence, which occurs only in a relatively small portion of the world's population (primarily people having northern European ancestry). This adaptation does not dictate a dietary requirement for milk products, but only confers persistence of the ability to digest milk sugar into adulthood.
In contrast, all humans have numerous very specific anatomical, physiological, and genetic adaptations to consumption of fruits, vegetables, nuts, and seeds.