Are Humans Omnivores? HTML version
Before examining the scientific evidence, there are serious problems with the proposition that humans are omnivores.
These philosophical issues fall into 2 distinct camps. Both of these issues seem to make the topic unsuited to scientific
1) Lack of a testable proposition
Claims that humans are biological omnivores are hampered by the lack of any clear set of rules (i.e. a testable hypothesis)
for establishing what an omnivore is. Some authors describe an omnivore as an animal that is neither a herbivore nor a
carnivore. However, a definition of what something is not, is not a classification, in this case omnivores are said to be "non-
specialists", able to eat either plant or animal matter. But these kinds of poorly constructed pseudo-definitions are weak,
because under conditions of domestication where technology is applied to foods, even unequivable herbivores can consume
processed animal remains.
2) Confusion of similarities and equivalences
Food processing technology can bypass adaptations, allowing animals to consume things they would naturally be incapable
of aquiring or consuming. Indeed the use of technology in preparing foods would tend to indicate a lack of adaptation.
Specifically, the applying of food processing technology, i.e. hunting with weapons or trapping, cutting, cooking and
tenderizing, to render animal matter edible, seems to contradict the notion of humans being adapted to capturing and
consuming animal matter. There is clearly a world of difference between wild animals which naturally procure and
consume animal foods, and civilised humans who consume meat, which is technologically processed animal matter.
Similar arguments can be made regarding other foods that humans must process using technology before consumption.
As has been demonstrated, while there is clearly a similarity in that both humans and non-human animals exist that eat
practically anything edible, the behaviours are in fact not equivalents. Wild animals procure and consume their food by
using innate biological systems, whereas humans obtain and consume a wide range of foods as a result of technology.
If we are forced to concede that humans can be called omnivores, even though this results from the use of technology, then
we must also accept that humans can fairly be called birds as a result of using flying machines, and fish as a result of using
underwater survival technology. Such positions are unacceptable, and if persued, only convince us that the claim that
humans are omnivores, is not based on any form of natural equivalence, as proponents intend when they claim that humans
Because the term omnivore is vague, it is not surprising that authors often differ in their classifications of the dietary status
of animals. Pilbeam(9) describes apes as very broadly "herbivores", as do Yerkes and Yerkes(4), whereas Maier(2) says
primates should be considered to be "omnivores". Opinions on how to classify primates in general, and chimpanzees, our
closest genetic relatives, seem to be at varience.
In order to classify digestive systems, Chivers has performed some of the most extensive study of mammal digestive
system anatomy, yet his research on humans is inconclusive. Summing up in 'Diet and Guts'(1) he states that human gut
anatomy is characteristic of meat-eating, or some other rapidly digested foods. However, his plots show the human
digestive anatomy is at the edge of the "carnivore" cluster. Even more critically, at the centre of the "carnivore" cluster is
Cebus capucinus (the white-fronted capuchin). According to The Pictorial Guide To The Living Primates, Cebus capucinus
eats 95 types of fruit that make up 65% of its diet, while leaves make up 15%. The remainder of the diet consists of berries,
nuts, seeds, shoots, buds, flowers, gums, bark and animal matter including insects, in that order. Cebus capucinus is
primarily a foli-frugivore, not a carnivore, but they have also been called omnivores, because they consume a range of
animal matter. Cebus capucinus is rumoured to have a digestive system somewhat like humans, and Chivers chart
demonstrates some similarity, but his carnivore data set seems to be misleading, and is not objectively defined. We should
be careful with using concepts such as "similarities", because they are subjectively formed.
Of the few examples of other species categorised as omnivores, none seem to closely resemble humans in their anatomy,
unless perhaps the chimpanzee is to be categorised as an omnivore. However, the chimpanzee is often described as a
frugivore, or foli-frugivore although others call it an omnivore and as we shall see, human anatomy is distinct from the