dental anatomy and function

Data on the form and function of our dental anatomy is consistent with our ancestral condition as a frugivorous species (1, 2). Our nearest genetic relatives, the other great apes have evolved in tangents towards greater folivory (gorilla) and towards meat eating (chimpanzee, bonobo and orang utan) (1). Humans chew at a slower rate consistent with herbivores (3) and have ‘incisiform canines’ (4), the incisor morphology being suited to a herbivorous diet (5).

  1. Pickford, Martin. (2005). Incisor-molar relationships in chimpanzees and other hominoids: Implications for diet and phylogeny. Primates; journal of primatology. 46. 21-32. doi:10.1007/s10329-004-0109-5
  2. Mark F. Teaford and Peter S. Ungar, Diet and the evolution of the earliest human ancestors, PNAS December 5, 2000 97 (25) 13506-13511. doi:10.1073/pnas.260368897 [PDF]
  3. Lucas, P. (2004). Dental Functional Morphology: How Teeth Work. Cambridge: Cambridge University Press. doi:10.1017/CBO9780511735011
  4. Thompson, J., Krovitz, G., & Nelson, A. (Eds.). (2003). Patterns of Growth and Development in the Genus Homo (Cambridge Studies in Biological and Evolutionary Anthropology). Cambridge: Cambridge University Press. doi:10.1017/CBO9780511542565
  5.  Agrawal K. R. and Lucas P. W. 2003The mechanics of the first biteProc. R. Soc. Lond. B.2701277-1282. doi:10.1098/rspb.2003.2361

digestive system anatomy

It had been thought that humans had a digestive system adapted to meat eating. Data from the comparative studies of the primate gut morphology indicate that humans are frugivores. These findings are convincing because they are consistent with findings from the dental morphology literature.

  1. Hladik, C.M. & Pasquet, P. Hum. Evol. (2002) 17: 199. doi:10.1007/BF02436371 [PDF]


Carnivores, omnivores and herbivores tend to have differences in alanine:glyoxylate metabolism (1). Herbivores are much less tolerant to cholesterol than carnivores (2), this being the cause of rampant heart disease amongst contemporary populations of omnivorous humans. Chimpanzees and other great apes share some of the same genetic characteristics with humans that are risk factors for heart disease. However chimpanzees are resistant to atherosclerosis at cholesterol levels that would cause atherosclerosis in humans (3). 

  1. Birdsey GM, Lewin J, Cunningham AA, Bruford MW and Danpure CJ, Differential Enzyme Targeting As
    an Evolutionary Adaptation to Herbivory in Carnivora, Mol. Biol. Evol. 21(4):632-646. 2004. doi:10.1093/molbev/msh054  [PDF]
  2. Roberts, W.C. (2008), The Cause of Atherosclerosis. Nutr Clin Pract, 23: 464-467. doi:10.1177/0884533608324586
  3. Varki N, Anderson D, Herndon JG, et al. Heart disease is common in humans and chimpanzees, but is caused by different pathological processes. Evol Appl. 2009;2(1):101–112. doi:10.1111/j.1752-4571.2008.00064.x [PDF]


Studies of body odour attractiveness indicate that people who consume meat produce body odours that are less attractive than non-meat eaters (1).  Our taste preferences are consistent with those of herbivores (2). Humans sleep less than omnivores of similar size (3), less sleep being suggestive of a more herbivorous diet. People routinely engaged in slaughter work develop psychopathological problems (4).

  1. Jan Havlicek, Pavlina Lenochova, The Effect of Meat Consumption on Body Odor Attractiveness, Chemical Senses, Volume 31, Issue 8, October 2006, Pages 747–752. doi:10.1093/chemse/bjl017 [PDF]
  2. Field KL, Bachmanov AA, Mennella JA, Beauchamp GK, Kimball BA (2009) Protein Hydrolysates Are Avoided by Herbivores but Not by Omnivores in Two-Choice Preference Tests. PLOS ONE 4(1): e4126., doi:10.1371/journal.pone.0004126i
  3. Siegel, J. Clues to the functions of mammalian sleep. Nature 437, 1264–1271 (2005). doi:10.1038/nature04285
  4. Dillard, Jennifer. (2007). A Slaughterhouse Nightmare: Psychological Harm Suffered by Slaughterhouse Employees and the Possibility of Redress through Legal Reform. Georgetown Journal on Poverty Law & Policy. [PDF]