The most telling quote from the article is “I didn’t want to do some faddish diet that my sister would do,” Mr. Durant said. This just reeks of pathetic insecurity, I'm not surprised the conclusions he came to were ridiculous.
Apparently, there's not even much of a consensus about what people used to eat back then. According to Wikipedia: However, there is little direct evidence of the relative proportions of plant and animal foods.[94] According to some anthropologists and advocates of the modern Paleolithic diet, Paleolithic hunter-gatherers consumed a significant amount of meat and possibly obtained most of their food from hunting.[95] Competing hypotheses suggest that Paleolithic humans may have consumed a plant-based diet in general,[58] or that hunting and gathering possibly contributed equally to their diet.[96] One hypothesis is that carbohydrate tubers (plant underground storage organs) may have been eaten in high amounts by our pre-agricultural humans.[97][98][99][100] However, the relative proportions of plant and animal foods in the diets of Paleolithic peoples probably varied between regions. For instance, hunter gatherers in tropical regions such as Africa probably consumed a plant-based diet, while populations in colder regions such as Northern Europe most likely obtained most of their food from meat.[101] http://en.wikipedia.org/wiki/Paleolithic#Diet_and_nutrition
This whole thing smacks of a silly trend among a small group of NY hipsters to sound cool and eat a shit load of meat.