Monday, January 7, 2008

Telesis File :The Natural Human Diet

According to biologists and anthropologists who study our anatomy and our evolutionary history, humans are herbivores who are not well suited to eating meat.

Unlike natural carnivores, we are physically and psychologically unable to rip animals limb from limb and eat and digest their raw flesh. Even cooked meat is likely to cause human beings, but not natural carnivores, to suffer from food poisoning, heart disease, and other ailments.

People who pride themselves on being part of the human hunter tradition should take a second look at the story of human evolution. Prehistoric evidence indicates that humans developed hunting skills relatively recently and that most of our short, meat-eating past was spent scavenging and eating almost anything in order to survive; even then, meat was a tiny part of our caloric intake.

Humans lack both the physical characteristics of carnivores and the instinct that drives them to kill animals and devour their raw carcasses. Ask yourself: When you see dead animals on the side of the road, are you tempted to stop for a snack? Does the sight of a dead bird make you salivate? Do you daydream about killing cows with your bare hands and eating them raw? If you answered "no" to all of these questions, congratulations—you're a normal human herbivore—like it or not. Humans were simply not designed to eat meat.

Although many modern humans eat a wide variety of plant and animal foods, earning us the honorary title of "omnivore," we are anatomically herbivorous. Biologists have established that animals who share physical characteristics also share a common diet. Comparing the anatomy of carnivores with our own clearly illustrates that we were not designed to eat meat.

Teeth and Nails

To contrast human physiology with that of carnivores, start at the beginning of the digestive tract. Teeth, nails, and jaw structure indicate that nature intended for people to eat a plant-based diet. They have much shorter and softer fingernails than animals and pathetically small "canine" teeth (they're canine in name only). In contrast, carnivores all have sharp claws and large canine teeth capable of tearing flesh.

The jaws of carnivores move only up and down, requiring them to tear chunks of flesh from their prey and swallow it whole. Humans and other herbivores can move their jaws up and down and from side to side, a movement that allows them to grind up fruit and vegetables with their back teeth. Like other herbivores, human back molars are flat and allow the grinding of fibrous plant foods. Carnivores lack these flat molars. If humans had been meant to eat meat, they would have the sharp teeth and claws of carnivores. Instead, their jaw structure, flat molars, and lack of claws indicate that they are best suited for a plant-based diet.

Dr. Richard Leakey, a renowned anthropologist, summarizes, "You can't tear flesh by hand, you can't tear hide by hand. Our anterior teeth are not suited for tearing flesh or hide. We don't have large canine teeth, and we wouldn't have been able to deal with food sources that require those large canines."

Stomach Acidity

After using their sharp claws and teeth to capture and kill their prey, carnivores swallow their food whole, relying on their extremely acidic stomach juices to do most of the digestive work. The stomach acid of carnivores actually plays a dual role-besides breaking down flesh, the acid also kills the dangerous bacteria that would otherwise sicken or kill the meat-eater.

As illustrated in the chart below, our stomach acids are much weaker in comparison because strong acids aren't needed to digest pre-chewed fruits and vegetables. In comparing the stomach acidity of carnivores and herbivores, it is obvious that humans fall into the latter category. We can cook meat to kill some of the bacteria and make it easier to chew, but it's clear that humans, unlike all natural carnivores, are not designed to easily digest meat.

Intestinal Length

Evidence of our herbivorous nature is also found in the length of our intestines. Carnivores have short intestinal tracts and colons that allow meat to pass through it relatively quickly, before it has a chance to rot and cause illness. Humans, on the other hand, have intestinal tracts that are much longer than carnivores of comparable size. Like other herbivores, longer intestines allow the body more time to break down fiber and absorb the nutrients from a plant-based diet.

The long human intestinal tract actually makes it dangerous for people to eat meat. The bacteria in meat have extra time to multiply during the long trip through the digestive system, and meat actually begins to rot while it makes its way through the intestines. Many studies have also shown that meat can cause colon cancer in humans.

Comparing our anatomies clearly illustrates the fact that the human body is built to run on a vegetarian diet. Humans have absolutely none of the distinguishing anatomical characteristics that either carnivores or even natural omnivores have. Read author John Robbins' discussion of the anatomical differences between humans and carnivores.

Here is a chart from "The Comparative Anatomy of Eating" by Dr. Milton Mills that compares the typical anatomical features of carnivores, omnivores, herbivores, and humans.2 Notice how closely human physical characteristics match those of herbivores. Review Dr. Mills' entire article on the topic.

While carnivores take pleasure in killing animals and eating their raw flesh, any human who killed an animal with his or her bare hands and dug into the raw corpse would be considered deranged. Carnivorous animals are aroused by the scent of blood and the thrill of the chase. Most humans, on the other hand, are revolted by the sight of raw flesh and cannot tolerate hearing the screams of animals being ripped apart and killed. The bloody reality of eating animals is innately repulsive to us, more proof that we were not designed to eat meat.

Ask yourself: When you see dead animals on the side of the road, are you tempted to stop for a snack? Does the sight of a dead bird make you salivate? Do you daydream about killing cows with your bare hands and eating them raw? If you answered "no" to all of these questions, congratulations—you're a normal human herbivore—like it or not. Humans were simply not designed to eat meat. Humans lack both the physical characteristics of carnivores and the instinct that drives them to kill animals and devour their raw carcasses.

If we were meant to eat meat, why is it killing us?

In addition to being anatomically ill equipped to digest meat in the short-term, the long-term damage that a meat-based diet wreaks on the human body confirms that we were not meant to eat flesh. Natural carnivores never suffer from heart disease, cancer, diabetes, strokes, or obesity, ailments that are caused in humans by the consumption of the saturated fat and cholesterol in meat.

Dr. William C. Roberts, M.D., editor of the authoritative American Journal of Cardiology, sums it up this way: "[A]lthough we think we are one and we act as if we are one, human beings are not natural carnivores. When we kill animals to eat them, they end up killing us because their flesh, which contains cholesterol and saturated fat, was never intended for human beings, who are natural herbivores."

Studies have shown that even when fed 200 times the amount of animal fat and cholesterol that the average human consumes each day, carnivores do not develop the hardening of the arteries that leads to heart disease and strokes in humans.4 Indeed, researchers have found that it is impossible for carnivores to develop hardening of the arteries, no matter how much animal fat they consume.5

Carnivores are capable of metabolizing all the fat and cholesterol in meat, but humans are a different story: Our bodies were not designed to process animal flesh, so all the excess fat and cholesterol from a meat-based diet makes us sick. Heart disease, for example, is the number one cause of death in America according to the American Heart Association, and medical experts agree that this ailment is the result of the consumption of animal products.6 In fact, meat-eaters have a 50 percent higher risk of developing heart disease than vegetarians, and a low-fat, completely vegetarian diet has been repeatedly used to unclog the arteries of heart disease patients—it not only prevents but also treats the disease!7 Learn more about animal products and heart disease.

In addition to pointing out the damage done by saturated fat and cholesterol, scientists have also shown that eating animal protein can be harmful to human health. We consume twice as much protein as we need when we eat a meat-based diet, and this leads to osteoporosis and kidney stones.8 Animal protein raises the acid level in human blood, causing calcium to be excreted from the bones to restore the blood's natural pH balance. This calcium depletion leads to osteoporosis, and the excreted calcium ends up in the kidneys, where it can form kidney stones. The strain of processing all the excess animal protein from meat can also trigger kidney disease in meat-eaters.

The consumption of animal protein has also been linked to cancer of the colon, breast, prostate, and pancreas. In fact, according to Dr. T. Colin Campbell, the director of the Cornell-China-Oxford Project on Nutrition, Health, and the Environment, "In the next ten years, one of the things you're bound to hear is that animal protein … is one of the most toxic nutrients of all that can be considered."

Eating meat can also have negative consequences for stamina and sexual potency. One Danish study indicated that "Men peddling on a stationary bicycle until muscle failure lasted an average of 114 minutes on a mixed meat and vegetable diet, 57 minutes on a high-meat diet, and a whopping 167 minutes on a strict vegetarian diet."9 Besides having increased physical endurance, vegans are also less likely to suffer from impotence.

Since we don't have strong stomach acids like carnivores to kill all the bacteria in meat, dining on animal flesh can also give us food poisoning. In fact, according to the USDA, meat is the cause of 70 percent of foodborne illnesses in the United States because it's often contaminated with dangerous bacteria like E. coli, listeria, and campylobacter.10 Every year in the United States alone, food poisoning sickens over 75 million people and kills more than 5,000.11 While carnivores can process all the saturated fat, protein, and bacteria in animal flesh, a meat-based diet can send humans to an early grave. Clearly, people were not intended to eat meat. Learn more about how meat affects human health.

If it's so unhealthy and unnatural for humans to eat meat, why did our ancestors turn to animal flesh for sustenance?

During most of our evolutionary history, we were largely vegetarian.12 You could probably figure this out by noting that all the great apes, our closest living relatives, are also predominantly herbivorous. Like apes, our bodies evolved to eat fruits, nuts, and vegetables.13

Harvard anthropologist Richard Wrangham and his colleagues first explained that root vegetables—and the ability to cook them—prompted the evolution of large brains, smaller teeth, modern limb proportions, and even male-female bonding.14 Plant foods like potatoes made up the bulk of our ancestors' diet and spurred our advancement as a species.

The addition of modest amounts of meat to the early human diet came with the invention of fire, which allowed us to eat meat without being killed by it (usually). This practice did not turn our ancestors into carnivores but rather supplemented their traditional plant foods and allowed early humans to survive in periods when plant foods were unavailable.

Anthropologists believe that early humans started to consume small amounts of meat when climate changes made plant foods scarce. During this period, starting a little over a million years ago, humans began to hunt animals for sustenance in the ever-changing landscapes they encountered during their migrations.15

Modern Humans

Fully modern human beings (Homo sapiens) evolved about 150,000 years ago in Africa and soon spread across the globe.16 With the advent of agriculture, about 23,000 years ago, humans began to gather seeds and cultivate crops to provide a more consistent food supply.17 Our ancestors occasionally killed animals for their flesh, but they still received most of their nutrition from plant sources. Until recently, only the wealthiest people could afford to feed, raise, and slaughter animals for their flesh. Consequently, prior to the 20th century, only the rich died from diseases like heart disease, obesity, and strokes.

During the past 50 years, traditional small-scale farms have been replaced by massive, mechanized agricultural operations. Technological advances have allowed factory farmers to produce huge quantities of food and ship it anywhere in the world, and agribusiness entrepreneurs soon bought out and consolidated smaller agrarian operations. When America was founded, roughly 90 percent of Americans lived on farms.18

Today, the percentage of Americans who farm for a living has fallen to less than 2 percent.19 The "family farm" is now practically extinct.

The industrialization of animal production has led to huge factory farms that raise thousands of animals in cramped, filthy warehouses. This crowding, combined with other cost-cutting practices (like grinding up the scraps from dead animals and feeding them back to the survivors) and huge agricultural subsidies (corporate welfare) has made meat cheap and readily available. In addition, our natural aversion to killing animals for food is bypassed by the modern farming system-immigrants and poor, rural Americans do the dangerous dirty work in the slaughterhouses, and the rest of us are never confronted with the task of killing the animals ourselves (or even having to watch it happen). Read more about factory farming.

Since 1950, the per capita consumption of meat has almost doubled; now that animal flesh has become relatively cheap and easily available, deadly ailments like heart disease, strokes, cancer, and obesity have spread to people across the socio-economic spectrum.20 And as the Western lifestyle spills over into less developed areas in Asia and Africa, they, too, have started to die from the diseases associated with meat-based diets.

"T. Colin Campbell, the former senior science advisor to the American Institute for Cancer Research, is outspoken on the diet/disease connection. He says, 'The vast majority of all cancers, cardiovascular diseases, and other forms of degenerative illness can be prevented simply by adopting a plant-based diet.'"21 In Vegan: The New Ethics of Eating, he states, "I now consider veganism to be the ideal diet. A vegan diet—particularly one that is low in fat—will substantially reduce disease risks. Plus, we've seen no disadvantages from veganism. In every respect, vegans appear to enjoy equal or better health in comparison to both vegetarians and non-vegetarians."22

William Castelli, M.D. says: "A low-fat, plant-based diet would not only lower the heart attack rate about 85 percent, but would lower the cancer rate 60 percent."23

Our anatomy reveals that we are herbivores, as does our natural aversion to meat and the fact that it is harmful to our health. Meat-eaters are out of step with our evolutionary past. Our closest living relatives—the great apes—and ancestral human populations are and have been predominately vegetarian. They may eat the occasional rodent and some raw bugs, but the vast majority of their caloric intake is herbivorous. The key to human health lies in adopting a diet that is consistent with their anatomy and evolutionary history.

Luckily for us, it has never been easier to eat a vegetarian diet. Modern society has been able to provide a healthy vegetarian alternative for all of our favorite meat-based dishes, and more and more restaurants and grocery stores are offering delicious meat-free options. Visit for free recipes, tips, and more.


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