Originally posted by Dr. Davis on 2016-04-12
on the Wheat Belly Blog, sourced from and currently found at: Infinite Health Blog.
PCM forum Index of WB Blog articles.

The Accidental Carnivore

Take a look at your hands: You’ve got nice fingernails . . . not claws. How about teeth? You’ve got relatively small teeth, lacking the sharp cutting power of large canine teeth. You’ve also got strong, somewhat thick-enameled molars. In short, we lack the natural tools of carnivory. While a hyena, jackal, lion or other carnivore can tear the throat of a gazelle with ease, you and I would not chance such a thing.

Based on such observations, some people say that humans are born herbivores and that carnivory is unnatural, perhaps a perversion of primate aggression. (All ruminant readers of the Wheat Belly Blog, however, are encouraged to continue reading the vegetarian literature.)

I’m going to propose a different perspective. I propose that Homo sapiens, likely derived from one or more herbivorous primates of the Australopithecine variety, is the exception to the rule that form determines function: Humans became carnivorous (or, more properly, omnivorous) because of their brains (and brains likely evolved as a consequence of this behavior). Let’s review the sequence that many anthropologists tell us occurred since the first Homo species walked (and climbed, given their residual arboreal capacity):

• The earliest Homo species likely killed small game for food, such as small reptiles and rodents, on their own, while scavenging the larger kill of natural carnivores. This may have provided the basis for rudimentary tool use, e.g., cracking open the skull or long bones of a scavenged gazelle with a rock. This precedes the taming of fire, so meat and organs were consumed raw. Nonetheless, the fat and protein was likely deeply satisfying to hungry Homo.
   
• Homo became more adept at creating tools and weaponry–The reign of the very successful Homo erectus and related strains witnessed the development of spears, knives, cutters, scrapers, pounding tools, all stone, of course. This made Homo a more effective hunter/trapper/killer of animals. Somewhere along the way, likely spottily and inconsistently, fire was used and tamed to cook food, making calories more bioavailable. (See Dr. Richard Wrangam’s excellent discussion about the role of fire in human evolution in his book, Catching Fire.)
   
• Homo developed the ability to group hunt. While non-verbal carnivores can group hunt, Homo likely discovered the substantial advantage that emerged with communication. Imagine taking down a wooly mammoth: one or more humans slash the tendons of the rear legs, for instance, while several humans distracted the creature from the front. Such collaborative efforts, surely terrifying, required some means of communication–language–as well as the vocal apparatus for speech (absent pre-Homo). It also requires an advanced frontal lobe that allows making future plans.

It is not entirely clear why or how, through this 2.4 million year long story of adaptation to life on earth in its varying habitats and climates, brain size increased 3-fold, from the 450 cc chimpanzee-sized brain of Australopithecus, to the 1600 cc brain of pre-agricultural Homo (e.g., Cro Magnon and Neandertal). Anthropologists speculate that the combined effects of animal flesh and organ consumption, increasing need for more effective tools and weapons, consuming meats and organs cooked over a fire, and the advantage of communication/language/vocalization fueled this growth in brain size, coupled with mutations favoring such phenomena. (Carnivory alone, of course, is insufficient explanation, else lions would be the smartest creatures on earth.)

So consumption of animal organs and flesh, acquired via the unique brain, technological, and cultural evolution of Homo, sets us apart from other animals. We are not exclusively herbivorous like Australopithecus, nor are we obligatorily carnivorous like a Bengal tiger. We are something in between, uniquely positioned and unlike any other creature.

And, of course, we are most definitely not evolutionarily suited to consume the modern grain products of agribusiness, the stuff that even ruminants struggle with.