- Cardiologist William C. Roberts hails
from the famed cattle state of Texas, but he says this without hesitation:
Humans aren't physiologically designed to eat meat. "I think the evidence
is pretty clear. If you look at various characteristics of carnivores versus
herbivores, it doesn't take a genius to see where humans line up,"
says Roberts, editor in chief of The American Journal of Cardiology and
medical director of the Baylor Heart and Vascular Institute at Baylor University
Medical Center in Dallas. © Stephen Kroninger
- As further evidence, Roberts cites the
carnivore's short intestinal tract, which reaches about three times its
body length. An herbivore's intestines are 12 times its body length, and
humans are closer to herbivores, he says. Roberts rattles off other similarities
between human beings and herbivores. Both get vitamin C from their diets
(carnivores make it internally). Both sip water, not lap it up with their
tongues. Both cool their bodies by perspiring (carnivores pant).
- Human beings and herbivorous animals
have little mouths in relation to their head sizes, unlike carnivores,
whose big mouths are all the better for "seizing, killing and dismembering
prey," argues nutrition specialist Dr. Milton R. Mills, associate
director of preventive medicine for the Washington, D.C.-based Physicians
Committee for Responsible Medicine (PCRM). People and herbivores extensively
chew their food, he says, whereas swallowing food whole is the preferred
method of carnivores and omnivores.
- Got Milk?
- Dr. Neal D. Barnard, PCRM's founder and
president, says humans lack the raw abilities to be good hunters. "We
are not quick, like cats, hawks or other predators," he says. "It
was not until the advent of arrowheads, hatchets and other implements that
killing and capturing prey became possible."
- Milk, another animal product, can also
be problematic for people. That's why, in response to the popular "Got
Milk?" ad campaign, Barnard's organization sponsored billboards this
past summer that read, "Got Diarrhea?"
- "Dairy foods are definitely not
a natural part of our diet," contends vegetarian dietitian and author
Virginia Messina, who fields the public's nutritional questions at www.VegRD.com.
"We only started consuming them about 10,000 years ago, which is very
recent in our evolution. Our physiology suggests that we really did not
evolve to consume dairy beyond early childhood."
- Three out of 10 adults are lactose intolerant,
meaning they can't digest the sugar in milk. So they likely suffer gas
or diarrhea when undigested lactose reaches the large intestine, according
to an April report in the Nutrition Action Healthletter.
- While celebrities sport milk mustaches
in ad campaigns, some research raises questions as to whether milk is a
better source of calcium than, say, spinach or collard greens. Echoing
the conclusions of research elsewhere, a Harvard University study of more
than 75,000 nurses found no evidence that nurses who drank the most milk
enjoyed fewer broken bones.
- Are We Omnivores?
- Milk's high protein actually could leach
calcium from bones, according to Dr. Walter Willett, of the Harvard School
of Public Health, speaking on the PBS program HealthWeek.
- "Drinking cow milk has been linked
to iron-deficiency anemia in infants and children; it has been named as
the cause of cramps and diarrhea in much of the world's population and
the cause of multiple forms of allergies as well. The possibility has been
raised that it may play a central role in the origins of atherosclerosis
and heart attacks," writes Dr. Frank Oski, former director of the
Johns Hopkins University Department of Pediatrics, in his book, Don't Drink
- As intriguing as these arguments may
be, the idea that humans are natural vegetarians has "no scientific
basis in fact," argues anatomist and primatologist John McArdle. Alarmed
by this growing belief, McArdle, a vegetarian, says the human anatomy proves
that people are omnivores.
- "We obviously are not carnivores,
but we are equally obviously not strict vegetarians, if you carefully examine
the anatomical, physiological and fossil evidence," says McArdle,
executive director of the Alternatives Research and Development Foundation
in Eden Prairie, Minnesota.
- According to a 1999 article in the journal
The Ecologist, several of our physiological features "clearly indicate
a design" for eating meat, including "our stomach's production
of hydrochloric acid, something not found in herbivores. Furthermore, the
human pancreas manufactures a full range of digestive enzymes to handle
a wide variety of foods, both animal and vegetable.
- "While humans may have longer intestines
than animal carnivores, they are not as long as herbivores'; nor do we
possess multiple stomachs like many herbivores, nor do we chew cud,"
the magazine adds. "Our physiology definitely indicates a mixed feeder."
- If people were designed to be strict
vegetarians, McArdle expects we would have a specialized colon, specialized
teeth and a stomach that doesn't have a generalized pH-all the better to
handle roughage. Tom Billings, a vegetarian for three decades and site
editor of BeyondVeg.com, believes humans are natural omnivores. Helping
prove it, he says, is the fact that people have a low synthesis rate of
the fatty acid DHA and of taurine, suggesting our early ancestors relied
on animal foods to get these nutrients. Vitamin B-12, also, isn't reliably
found in plants. That, Billings says, left "animal foods as the reliable
source during evolution."
- History argues in favor of the omnivore
argument, considering that humans have eaten meat for 2.5 million years
or more, according to fossil evidence. Indeed, when researchers examined
the chemical makeup of the teeth of an early African hominid that lived
in woodlands three million years ago, they expected to learn that our ancestor
lived on fruits and leaves. "But the isotopic clues show that it ate
a varied diet, including either grassland plants or animals that themselves
fed on grasses," reported the journal Science in 1999.
- So, the question remains: Are humans
natural vegetarians? In the end, whether a person lives a vegetarian lifestyle
has less to do with esoteric matters of anatomy and more to do with ethics
and personal values. The architecture of the human body offers no simple
- A Service of E/The Environmental Magazine.
Copyright © 2002. All Rights Reserved.
- From Lotus
- Hello Jeff,
- I have been researching this issue for a while now, and
would like to 'pick a few bones' in the latter part of this article.
- 'Herbivore', 'omnivore' and 'carnivore' are not the only
dietary biological adaptations. It was important to mention in the context
of this essay 'Frugivores', which are species that eat primarily fruits.
- It is evident that early hominids were not pre-adapted
to eating meat.- 'While comparable shearing crest length studies have
not been conducted on early hominids, australopithecines certainly have
relatively flat molar teeth compared with many living and fossil apes.
These teeth were well-suited to breaking down hard, brittle foods including
some fruits and nuts, and soft, weak foods such as flowers and buds; but
again, they were not well-suited to breaking-down tough pliant foods like
stems, soft seed pods, and meat. ..' http://www.cast.uark.edu/local/icaes/conferences/wburg/posters/pungar/satalk.ht
- But humans have increased consumption of flesh foods
over time, probably in order to survive in poor environments when there
was a scarcity of fruits and nuts, and it has been our reliance on flesh
that has allowed metabolic relaxation in the synthesis of taurine, although
humans can still synthesize it from cystein in the liver and from methionine
(veg' sources- beans, garlic, lentils, onions, seeds, soybeans) elsewhere
in the body, as long as sufficient quantities of B6 are present (veg' sources-
brewer's yeast, carrots, peas, spinach, sunflower seeds, walnuts, wheatgerm,
avocado, bananas, beans, blackstrap molasses, broccoli, brown rice and
other whole grains, cabbage, cantaloupe, corn, dulse, plantains, potatoes,
rice bran, soybeans and tempeh).
- The truly "essential" fatty acids are Linoleic
Acid (LA) and Alpha Linolenic Acid (ALA). LA and ALA are used to produce
other fatty acids, including; Gamma Linolenic Acid, Eicosapentaenoic Acid
(EPA), and Docosahexaenoic Acid (DHA), which in turn produce eicosanoids.
We generally get an excess of Linoleic acid from foods containing vegetable
oils, but very little of the omega-3s, Good plant food sources include
flaxseed and walnuts. (Factors including the consumption of saturated and
trans-fats, sugar, alcohol, the taking of prescription medications, viral
infections, stress, and diabetes can inhibit the conversion of LA to GLA.
Insufficient quantities of zinc, magenesium, Vit. c, B6 and niacin also
slow the process.)
- Hydrochloric acid is necessary for the digestion of protein.
Proteinous *nuts* require the hydrochloric acid of the stomach to provide
an adequate medium for the enzyme pepsin to act on the protein. But true
carnivorous (meat eating animals, and 'omnivores' are meat eating as well)
have in their digestive tracts a highly concentrated hydrochloric acid,
about 1100% more so than ours.
- Vitamin B12 is produced by bacteria. It is naturally
present in a healthy natural environment, and consequently on healthy natural
organic unwashed plant foods.
- I am mystified as to how John McArdle can state that
humans are 'omnivores' and then go on to say; "the best arguments
in support of a meat-free diet remain ecological, ethical, and health concerns
(http://www.vrg.org/nutshell/omni.htm). If humans have really adapted to
eating animal flesh, as are true omnivores (pigs, bears), then why would
there be any 'health concerns'?
- Sincerely, Lotus http://www.iol.ie/~creature/creature.htm
See also http://www.iol.ie/~creature/BiologicalAdaptations.htm