The major causes of disease and death in western
countries are chronic cardiovascular and metabolic diseases, and cancers.
These diseases have been linked to diets high in meat and animal fat, and
low in fruits, vegetables, unprocessed carbohydrates and fiber. Extensive
research data have led many nutrition authorities to conclude that
westerners should make major changes in their diet and lifestyle to
promote better health and reduce risk factors for chronic disease. In
effect, current consensus guidelines encourage Americans and other
westerners to adopt a diet based more on plant rather than animal foods.
Why should this be?
Standard western nutritional dogma "classifies" human
beings as omnivores. The statement "humans are omnivores" has been
repeated so often that it has acquired the patina of received truth. But
like a patina, the "truth" inherent in this statement is only microns
While it may be true that most humans are "behavioral"
omnivores (that is, they choose to include meat
in their diet) this behavioral fact says nothing
about whether including meat in our diet is an appropriate choice from an
anatomic, physiologic and heath perspective. What is surprising is that
despite abundant evidence showing that large amounts of meat and other
animal foods in one's diet leads to all types of chronic diseases, and
that varied plant-based diets promote better heath, the idea that humans
are supposed to be omnivores has rarely been challenged or critically
examined by the scientific community. Thus, although national health
policy guidelines clearly direct us away from animal foods and towards a
plant-based diet, many in the scientific community remain oblivious to
what is being implied. That implication is that humans are not omnivores
inasmuch as increasing amounts of animal foods in the diet promote
increasing levels of chronic disease.
Clearly, it is difficult to arrive at or recognize "the
answer" if one never asks the appropriate question.
A Question of Design
Animals who eat meat and those who eat plants face very
different issues when dinner time arrives. Plants, because they are
sedentary, encase their tissues in tough fibrous coverings for support and
protection, and thus require a large amount of digestive processing to
extract nutritional value from them. By contrast, "meat" (in the form of
live animals) usually does not want to be eaten and is, therefore,
recalcitrant, combative and uncooperative - it
tends to run away.
Accordingly, plant eaters (herbivores) are optimized for
foraging, batch feeding and prolonged digestion, whereas meat eaters
(carnivores/omnivores) are designed for predation and the consumption of
huge, infrequent meals.
Meat eaters are all equipped for short bursts of extreme
speed that allows them to ambush and/or run down prey. Their limbs have
been lightened to allow for fast running and their paws have been modified
into compact clubs armed with claws.
When tackling struggling prey, the most vulnerable parts
of their anatomy - the abdomen and gonads
- are shielded behind the muscular armored
chest. Their incisors have been reduced to short pointed pegs, while their
canines are huge sharp elongated daggers used for ripping and killing.
Their jaw joint is on the same plane as their cheek teeth, and there is no
horizontal side-to-side motion of the lower jaw.
This makes their jaws very stable and allows them to
operate like a pair of shears. Their molars are sharp, jagged and
blade-shaped. The upper molars vertically slide past the lower molars in a
slicing motion when the jaw is closed. These animals do not chew their
food. Instead, they slice off huge chunks of meat and swallow them whole.
They do not have digestive enzymes in their saliva since flesh-digesting
enzymes released in the unprotected mouth would quickly destroy the oral
Their strongly acidic stomachs are huge storage vats
that account for 60-70% of the total capacity of their GI tracts. Meat has
no fiber and is, therefore, easily digested. Thus, their small intestines
are very short (only 3-6 times their body length) and are optimized for
protein and fat absorption. Their large intestines are short straight and
smooth and designed for evacuation purposes only.
What about "By-design" Omnivores?
The one design concession "by-design" omnivores such as
bears and raccoons have made to plant eating is that one or more pairs of
their molars have modified from sharp blades to flattened grinding
This allows them to crush and swallow a limited amount
and range of plant foods such as fruits, berries, roots and tubers.
However, they otherwise retain the typical carnivore tooth design and jaw
mechanics, and their short small intestines do not allow them to
adequately handle large amounts of plant fiber. Hence, a true natural
omnivore is a carnivore that has been minimally modified to eat a limited
range of soft, pulpy plant foods, but is still equipped to run down, kill,
dismember and consume prey.
I Herd That!
Large mammalian herbivores tend to be social animals
living in large herds/communities/cities. Because they must cover
significant distances looking for and gathering plant foods, their limbs
are modified for prolonged energy-efficient standing and walking. Instead
of claws, their nails are blunt and used for digging and peeling. They
have muscular lips, a small mouth opening and well-developed cheek
This creates a "walled-in" oral cavity that facilitates
the crushing and grinding action of chewing. The jaw joint is above the
plane of the cheek teeth and the lower is "L-shaped" causing the upper
molars to come to rest on top of the lower molars when the jaw is closed.
This allows the jaw to function like a nut cracker rather than a pair of
The upper molars cannot vertically slide past the lower
molars. But because the lower jaw has a pronounced horizontal side-to-side
motion, the upper and lower molars horizontally slide across one another
creating the grinding action of chewing. Accordingly, the molars are not
sharp and blade-shaped, but are squared, flat-topped and abut one another
forming extended grinding surfaces. The incisors are broad, flattened and
spade-shaped and used for cropping and peeling. The canines may be absent,
as in cows and sheep; shortened and reduced, as in horses and humans; or
dagger-like and used for defense, as in hippos and some primates.
Herbivores also usually have carbohydrate digesting enzymes in their
saliva that begins the process of digestion while food is still in the
mouth. In fact, the purpose of chewing (including chewing the cud) is to
mix food with digestive enzymes to facilitate the process of digestion.
Plant tissues contain large amounts of fibrous material.
The end result is that plant foods require extensive processing to extract
their nutritional content. Because of this, herbivores consume smaller,
more frequent meals, and tend to have much longer and, in some cases, much
more elaborate digestive tracts than their meat-eating counterparts.
In a typical herbivore, the stomach holds less than 30%
of the total capacity of the GI tract. On the other hand, the small
intestine is extremely long and is usually more than 10-12 times the body
length and has an unlimited capacity for carbohydrate absorption. The
large intestine or colon is also relatively long and complex and
frequently has a pouched appearance.
Here's Looking at You
In every respect, humans show the anatomic and
physiologic features typical of an herbivore. A full and complete
discussion of these features is well beyond the scope of this short
article. What follows is a random sampling of facts.
Upright posture leaves the human abdomen, ovaries and
testes completely exposed and, potentially, fatally vulnerable. Whereas
standing and walking are very energy-efficient for humans, running is not.
We are extremely slow runners and have very poor
stamina. We have a carbohydrate-digesting enzyme in our saliva called
The human esophagus does not handle poorly chewed food
very well. Over 90% of the people who choke to death each year choke on
Human body length (head to tail bone) is typically 2.5
to 3 feet. Thus, at >25-30 feet in length, the human small intestine is
clearly designed for digesting plant material.
Only herbivores have an appendix. No matter how much fat
and cholesterol you feed carnivores like dogs and cats, they NEVER develop
coronary artery disease.
In places where people eat a high fiber, whole food
diet, appendicitis and diverticulosis are unknown.
Studies in western countries have shown that on average,
vegetarians have smarter children, suffer significantly lower rates of
chronic disease, obesity and dementia, and live longer than their
So, to answer the question posed by the title of this
piece: NO, we are NOT designed to eat meat!
And God said, "Behold, I have given you every plant
yielding seed which is upon the face of all the earth, and every tree with
seed in its fruit; you shall have them for food." - Genesis 1:29