There are a number of popular myths aboutvegetarianism that have no scientific basis infact. One of these myths is that man is naturallya vegetarian because our bodies resemble planteaters, not carnivores. In fact we are omnivores,capable of either eating meat or plant foods. Thefollowing addresses the unscientific theory of manbeing only a plant eater.
Much of the misinformation on the issue of man'sbeing a natural vegetarian arises from confusionbetween taxonomic (in biology, the procedure ofclassifying organisms in established categories)and dietary characteristics.
Members of the mammalian Order Carnivora may ormay not be exclusive meat eaters. Those which eatonly meat are carnivores. Dietary adaptations arenot limited by a simple dichotomy betweenherbivores (strict vegetarians) and carnivores(strict meat-eaters), but include frugivores(predominantly fruit), gramnivores (nuts, seeds,etc.), folivores (leaves), insectivores(carnivore-insects and small vertebrates), etc. Is is also important to remember that the relationbetween the form (anatomy/physiology) and function(behavior) is not always one to one. Individualanatomical structures can serve one or morefunctions and similar functions can be served byseveral forms.
The key category in the discussion of human dietis omnivores, which are defined as generalizedfeeders, with neither carnivore nor herbivorespecializations for acquiring or processing food,and who are capable of consuming and do consumeboth animal protein and vegetation. They arebasically *opportunistic* feeders (survive byeating what is available) with more generalizedanatomical and physiological traits, especiallythe dentition (teeth). All the available evidenceindicates that the natural human diet isomnivorous and would include meat. We are not,however, required to consume animal protein. Wehave a choice.
There are very few frugivores amongst the mammalsin general, and primates in particular. The onlyapes that are predominantly fruit eaters (gibbonsand siamangs) are atypical for apes in manybehavioral and ecological respects and eatsubstantial amounts of vegetation. Orangutans aresimilar, with no observations in the wild ofeating meat.
Gorillas are more typically vegetarian, with lessemphasis on fruit. Several years ago a veryelegant study was done on the relationship betweenbody size and diet in primates (and some othermammal groups). The only primates on the listwith pure diets were the very small species (whichare entirely insectivorous) and the largest (whichspecialize in vegetarian diet). However, thespectrum of dietary preferences reflect the dailyfood intake needs of each body size and therelative availability of food resources in atropical forest. Our closest relatives among theapes are the chimpanzees (i.e., anatomically,behaviorally, genetically, and evolutionarily),who frequently kill and eat other mammals (including other primates).
As far back as it can betraced, clearly the archeological recordindicates an omnivorous diet for humans thatincluded meat. Our ancestry is among thehunter/gatherers from the beginning. Oncedomestication of food sources began, it includedboth animals and plants.
Relative number and distribution ofcell types, as well as structural specializations,are more important than overall length of theintestine to determining a typical diet. Dogs aretypical carnivores, but their intestinalcharacteristics have more in common withomnivores. Wolves eat quite a lot of plantmaterial.
Nearly all plant eaters havefermenting vats (enlarged chambers where foodssits and microbes attack it). Ruminants likecattle and deer have forward sacs derived fromremodeled esophagus and stomach. Horses, rhinos,and colobine monkeys have posterior, hindgut sacs. Humans have no such specializations.
Although evidence on the structure andfunction of human hands and jaws, behavior, andevolutionary history also either support anomnivorous diet or fail to support strictvegetarianism, the best evidence comes from ourteeth.
The short canines in humans are a functionalconsequence of the enlarged cranium and associatedreduction of the size of the jaws. In primates,canines function as both defense weapons andvisual threat devices. Interestingly, theprimates with the largest canines (gorillas andgelada baboons) both have basically vegetariandiets. In archeological sites, broken humanmolars are most often confused with brokenpremolars and molars of pigs, a classic omnivore.On the other hand, some herbivores havewell-developed incisors that are often mistakenfor those of human teeth when found inarcheological excavations.
These indicate we could beomnivores. Saliva and urine data vary, dependingon diet, not taxonomic group.
Intestinal absorption is a surfacearea, not linear problem. Dogs (which arecarnivores) have intestinal specializations morecharacteristic of omnivores than carnivores suchas cats. The relative number of crypts and celltypes is a better indication of diet than simplelength. We are intermediate between the twogroups.
Humans are classic examples of omnivores in allrelevant anatomical traits. There is no basis inanatomy or physiology for the assumption thathumans are pre-adapted to the vegetarian diet. For that reason, the best arguments in support ofa meat-free diet remain ecological, ethical, andhealth concerns.
[Dr. McArdle is a vegetarian and currentlyScientific Advisor to The AmericanAnti-Vivisection Society. He is an anatomist and aprimatologist.]
The following information is taken fromThe NewYork Times, May 15, 1979. According to Dr. AlanWalker, a Johns Hopkins University anthropologist,Homo Erectus, the species immediately ancestorialto our own Homo Sapiens, had evidence of anomnivorous diet. Every Homo-Erectus tooth foundwas that of an omnivore. However, a small sampleof teeth from the human-like species during a 12million year period leading up to the Homo-Erectusperiod, indicates the earlier species may havebeen a fruit eater. Even if this species, waybefore our own, lived on a fruit diet, theyprobably would not have consumed what we considertypical fruits. Hundreds of plants produce fruitsthat are tougher, more substantial foods than whatwe eat today.
Quoted from an editorial by William CliffordRoberts, M.d., Editor-in-Chief of theAmericanJournal of Cardiology:
"When we kill animals toeat them, they end up killing us because theirflesh, which contains cholesterol and saturatedfat, was never intended for human beings, who arenatural herbivores."
Quoted from "WHAT DID OUR ANCESTORS EAT?" inNutrition Reviews, by Stanley Garn, Professor ofNutrition and Anthropology, and William Leonard,Assistant Professor of Human Biology:
"Thesepeople of Upper Pleistocene, and later those ofthe mesolithic, were our immediate ancestors, nolonger hunters exclusively and with whole-grainproducts and a variable amount of roots, fruits,leafy vegetables and nuts in their diet. We mustgrant them a mixed diet, with animal fat providinga smaller proportion of their food energy than wasprobably true for the Neanderthals."For additional information, please see articles:
This article was originally published in theMay/June 1991 edition ofVegetarian Journal,published by:
The Vegetarian Resource Group
P.O. Box 1463
Baltimore, MD 21203
(410) 366-VEGE
| ||||
Last Updated August 30, 2000 | Graphic design by |  | ||
