Wait—that grass-fed bacon you’ve been pigging out on may not be truly Paelo? That’s right, according to the co-author of the paper, Ken Sayers, PhD, an anthropologist at the Language Research Center of Georgia State University. Here, he shares some revealing tidbits from his work that might make you think twice about jumping (or staying) on the Paleo bandwagon. 

  1. There is no one Paleo diet.The Paleolithic Era began as early as 2.6 million years ago (around the emergence of the first stone tools) and lasted all the way until the advent of widespread agriculture, about 10,000 years ago. It saw the rise of many different hominids (or human-like species) with varying brain sizes, dental makeups, and motor skills—all factors that play a role in diet. Add in the fact that our ancestors were spread out over an entire continent (Africa) and later an entire planet made up of different environments with unique climates and food resources, and suddenly the question What did our ancestors eat? gets pretty complex. “People, including some scientists, have always wanted to pigeonhole [ancient man] as hunters, scavengers, gatherers, et cetera,” Sayers says. “There are few signals of dietary specialization at any stage of human evolution…There is no single ‘Paleo diet.’ "
  2. It’s still extremely difficult to deduce exactly what our ancestors ate. Okay, so the era was super long and differed from time to time and place to place, but can’t scientists generalize what our ancestors are? “Technologies that allow us to estimate some aspects of diet—such as the study of wear on teeth, the chemical makeup of dental enamel, and bits of plant silica on teeth—are valuable, but they really give only a very incomplete picture,” Sayers says. Getting that complete picture also requires extensive research of a creature’s environment, food sources likely to be in that environment, and cognitive ability (should I pick that fruit and eat it?), among other factors—an exhaustive process even for seasoned anthropologists. 
  3. There’s no agreement on the Paelo diet among professionals, either. Biologists from the 19th century onward have put forth theories about hominid diets, and just about every one is hotly debated. “Many of the most enduring controversies [of anthropology] have involved the evolution of the human diet,” Sayers says. Darwin speculated that early hominids were hunters, but in the mid 20th century, some research pointed to scavenging over hunting. By the 1970s, plant foods were the new focus of study. New findings continue to fuel the debate today.
  4. Our ancestors survived by not being picky eaters.  While we can say with confidence that Homo erectus wasn’t eating canned frosting, he also wasn’t stopping to consider a food’s fiber content or to make sure 35% or his calories were coming from protein, the way some Paleo guidelines suggest. “The reasons we and earlier hominids were so successful [as a species] is because of ecological—including dietary—flexibility,” says Sayers. In other words: Our ancestors both before and during the Paleolithic were opportunistic eaters who likely weren’t loyal to any specific combination of foods to get the energy they needed.  The bottom line: True, the modern-day Paleo Diet does eliminate excess sugar and unhealthy processed foods, but basing your daily food intake on a body of research that’s still under revision may not be the ticket to lifelong health and longevity. “Regardless of the diet chosen by someone living today,” Sayers concludes, “he or she should try to accomplish someone rarely achieved by earlier hominids—living past the age of 30.” MORE: Can The Paleo Diet Help You Lose Weight?