Why Do Chimpanzees Eat Meat?

Chimpanzees eat meat for two simple reasons: they can catch it and they like it. Chimpanzees are particularly likely to eat meat during the dry season, when shortages of the foods that normally make up the bulk of theirdiet cause them to lose weight. Although the meat may be a useful source of calories during the dry season, wild chimpanzees don’t need to include meat or any other animal-based food in their diet to fulfill their needs for protein or any of the amino acids. In fact, plants provide all of the nutrients that are known to be essential for a chimpanzee, except for vitamin D (which they get from the abundant sunshine in Africa) and vitamin B12 (which comes from bacteria).

Many people think that I am silly for asking where gorillas get their protein. They tell me that I should talk about chimpanzees instead. Often, they inform me that chimpanzees are far more similar to human beings than gorillas are, as if I couldn’t tell that just by looking. These people are missing my point: gorillas are the largest and most powerful living primate and yet are the closest to following what human beings would consider a vegan diet. Chimpanzees and human beings don’t need to eat meat to grow up big and strong because gorillas grow up to be far bigger and stronger without it. Lawyers may recognize this as an a fortiori argument.

If a male gorilla, whose digestive system is practically identical to a human being’s, can get enough protein from vegetables to grow to weigh more than 400 pounds and be ten times as strong as a man, why shouldn’t I expect that a relatively puny human Olympic weightlifter could also get enough protein from a plant-based diet? My intent is to ridicule the Four Food Groups dogma that I was taught in sixth grade.

Gorillas don’t hunt or fish, and they don’t keep cows or chickens. As a result, they don’t eat meat or fish, dairy products or eggs. The only animal-source food they eat is “the other, other white meat”: termites, slugs, and other creepy-crawlies. These foods would make an insignificant contribution to the gorillas’ protein intake, which is already high because protein accounts for a high percentage of the calories in leaves.

Bugs and slugs could be a useful source of vitamin B12, a micronutrient that is made by bacteria in their intestines. Vitamin B12 is also produced by bacteria in a primate’s gastrointestinal tract. However, the vitamin may be produced so far along in the intestinal tract that it isn’t absorbed efficiently. No plants make vitamin B12, but gorillas and chimpanzees can probably get enough vitamin B12 from the bacteria in the bugs they eat and in the dirt that clings to their food. Plus, apes are not meticulous about washing their hands, if you get my drift. If you are worried about getting enough vitamin B12, you don’t have to eat dirt or bugs. You can get it in a nice, clean tablet instead.

I don’t ask where chimpanzees get their protein because chimpanzees do eat some meat. Chimpanzees probably eat less meat than just about any human population other than Buddhist monks. Nevertheless, many people want to use chimpanzees’ meat consumption as an excuse for humans to eat meat.

The fact that chimpanzees’ meat consumption is largely seasonal goes far toward explaining why human beings have always eaten meat. Chimpanzees are most likely to eat meat during the time of year when they are losing weight because their usual foods are in relatively short supply. People think of meat as a source of protein, but it’s mainly a source of calories, especially from fat. Meat is also a good source of sodium, which is in relatively short supply in the chimpanzees’ fruit and vegetable diet.

The fact that chimpanzees eat the most meat during times of food shortages suggests that their food choices follow a pattern that biologists call optimal foraging theory. Animals try to get the most calories for the least effort and without getting hurt. Optimal foraging theory explains why chimpanzees eat meat but gorillas don’t, and why chimpanzees eat more meat during times of food shortage.

Chimpanzees are mainly fruit eaters, but they also eat a lot of vegetables. The problem with fruit is that it’s seasonal. Worse yet, a fruit tree represents a rich enough source of calories that animals will fight over it. When fruit is scarce, chimpanzees can use the skills they developed in fighting over the fruit to engage in predatory behavior. Also, chimpanzees are small enough and fast enough that they are reasonably good hunters.

Gorillas, on the other hand, mainly eat leaves. There are generally plenty of leaves to go around, and a leafy plant is generally so poor in calories that it’s not worth fighting to protect. To subsist on leaves, however, you have to eat an enormous volume of food. Since leaves are so low in calories, leaf-eaters have to be good at conserving their energy. That’s why gorillas have such a placid disposition. For a gorilla, hunting is simply not worth the effort. They are too big and slow to catch very much, and they’re large enough that they’d risk injury if they got too reckless.

Chimpanzees use twigs to fish for termites, and gorillas don’t. Some people think that this fact means that chimpanzees are smarter than gorillas. I don’t. If you are a juvenile gorilla or a pregnant or nursing female gorilla, you don’t need to mess around with a little bitty twig to get a few termites. All you have to do is wait for the silverback to knock over a rotting tree. Then all of you can eat as many termites as you’d like.

Some people have argued that the balance between animal and plant foods in a hunter-gatherer society’s diet represents the optimal balance for human nutrition. I think that’s idiotic. Hunter-gatherer peoples (or should I say, gatherer-hunter peoples) tend to follow optimal foraging theory just like any other opportunistic feeder. Their goal is to survive in the short term, not to avoid breast or prostate cancer in middle or old age. The main threat to their short-term survival is starvation.

Meat represents a concentrated source of calories. The fact that a relatively high percentage of these calories comes from protein is actually a disadvantage. Hunting peoples prefer the fattiest foods. People who end up having to subsist on extremely low-fat meat, such as rabbit, are prone to a problem called fat-hunger or rabbit starvation. This problem probably results from a diet that has too much protein and not enough carbohydrate or fat. On a low-carb diet and during starvation, the body has to make its sugar supply out of protein. Perhaps the body can make only so much sugar out of protein. As long as you are eating enough fat to meet most of your energy needs, your body can make enough sugar out of protein to feed your brain. If you were eating protein but not enough fat or carbs, you could end up in serious trouble. So you could end up in trouble from a diet that is too high in protein. In contrast, it is practically impossible to avoid getting enough protein, as long as you are eating enough unrefined plant foods to get enough calories.

Famine is not a significant cause of death in the United States. In fact, people in the United States are far more likely to die of the diseases of affluence, such as heart disease and cancers of the breast and prostate. Animal-based foods and fatty processed foods are the main contributing causes of the diseases of affluence. The ability to use animals for food may have helped human beings survive to the modern era, especially in the Arctic, but animal-based foods are a major cause of death and disability in the United States today. Think about that the next time you hear someone promoting a “Paleo” diet.

A Fish Is Not a Vegetable!

Lately, lots of people have been claiming that seafood is an important part of a health-promoting diet for human beings. Some of the hype comes from the seafood industry, and some of it comes from people who simply want an excuse to eat seafood. In reality, the health benefits of the so-called pescetarian diets (a vegetarian diet plus seafood) result from the fact that they include a lot more starch and vegetables than is customary in the standard American diet, while excluding some of the most dangerous animal-based foods. The starch and vegetables are good for you. Avoiding meat and milk from mammals and meat and eggs from birds is good for you. Unfortunately, the wine and seafood and olive oil in the “Mediterranean” diet do more harm than good.

It has always struck me as illogical for people to call themselves vegetarian if they eat seafood, which is the general term used to include edible fish and shellfish. (Yes, there are some edible plants that grow in seawater, but they’re generally called sea vegetables rather than seafood.) Fish are not vegetables. They are animals. So are shellfish, a category that includes mollusks such as oysters and crustaceans such as shrimp and lobster. If you are eating animals, you’re not vegetarian.

Many people eat fish because they are afraid that a purely plant-based diet wouldn’t provide enough protein to maintain their health. That’s nonsense. Protein deficiency is simply not a real concern. As long as you get enough calories from any practical diet based on unrefined plant foods, you will automatically get enough protein—unless you have some bizarre digestive or metabolic disease.

Rather than worrying about not getting enough protein, most people should be worried about the effects of eating too much protein. When you eat more protein than you need, your body turns the excess amino acids to sugar, releasing toxic waste products such as ammonia and sulfuric acid. In contrast, burning carbohydrates and fats for energy produces just carbon dioxide and water. The toxic byproducts of a high-protein diet can harm the liver and kidneys, as well as promoting osteoporosis. One study showed that people from the North Slope of Alaska had high rates of bone loss as a result of their high-protein diet, even though their calcium intake was high because they were eating fish bones.

Seafood is animal tissue, and it has the same faults as any other animal tissue. It contains cholesterol, too much protein and fat, and no starch or fiber. Fish and other sea creatures don’t provide any essential nutrients that you can’t easily get from other sources. Plants contain all of the nutrients that are essential in human nutrition except for vitamin D (which you get from sunshine) and vitamin B12 (which comes from bacteria). Even the omega 3 fatty acids in fish oil came from the plants that were at the bottom of the fish’s food chain.

Another problem with animal tissue, including seafood, is the buildup of toxic substances, including heavy metals and fat-soluble chemicals such as dioxin. This problem is called bioaccumulation. The higher up in the food chain an animal is, the worse this problem tends to be. You can avoid this problem by eating plants instead of animals.

In short, the hype about a “pescetarian” diet is just hype. People are better off just eating plants.

Photo by Pardee Ave.

Starchy, Low-Fat Diets Reduce Deaths From Type 2 Diabetes

Here is an interesting article that was published in the Proceedings of the Royal Society of Medicine in 1949. It points out that type 2 diabetes is common in places where people eat a fatty, low-carb diet and rare in places where people eat a starchy, low-fat diet. When a population that had been eating a fatty diet switches to a starchy diet, such as under rationing in wartime, the number of people who die of complications of diabetes falls off dramatically. See the graph on page 324 to see the effects of rationing, economic slump, and the introduction of insulin therapy on the number of people who died of diabetes in England and Wales in the early 20th century.

The author pointed out that you can see the same relationship between high fat consumption and deaths from diabetes all over the world:

There thus seems to be a universal relation between diet and diabetic mortality. The dietetic factor most closely related is fat consumption.

It may seem odd that the introduction of insulin therapy didn’t make a dent in the graph.  That’s because most people with diabetes have type 2 diabetes, which used to be called non–insulin-dependent diabetes. You’d see a different picture if you looked at a graph of deaths from type 1 diabetes, which used to be called insulin-dependent diabetes.

Note: For a clear explanation of why high-carbohydrate diets are good for people with any type of diabetes, see my book Thin Diabetes, Fat Diabetes: Prevent Type 2, Cure Type 2.

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Where Do Elephants Get Their Protein?

I chose the gorilla motif for this blog because gorillas are the biggest and most powerful primates, along with being about as close as possible to vegan as you can get while eating many pounds per day of vegetation in a rain forest. I wanted to point out that people simply don’t have to worry about getting enough protein or calcium from a plant-based diet. In reality, the animal-based foods that we have been urged to eat don’t provide any nutrients that we can’t easily get from plants or bacteria. If you are still worried about protein, think about where elephants get their protein. Elephants are even bigger and even stronger than gorillas. A big elephant can eat up to 600 pounds of food a day.

Photo by mcoughlin

Is the Child Resisting Toilet Training? Or Merely Constipated?

Yesterday, a friend of mine told me about a four-year-old boy who was “resisting” being toilet trained. She said that the child would urinate in the toilet but that he’d “hold it” for three days rather than defecate in his potty. I told her that I couldn’t imagine that anybody who eats a high-fiber vegan diet could “hold it” for three days, even if he tried, unless he was taking morphine or some other drug that shuts down gut motility. I said that the child’s problem didn’t sound to me like resistance to potty training. It sounded like constipation. His refusal to go on the potty probably reflects the fact that his bowel movements are uncomfortable or even agonizingly painful, and it’s probably because he’s being fed dairy products and a lot of processed food. She admitted that the poor child was being fed cow’s milk and wasn’t eating much fruit and vegetables or even whole grains.

Think about it. If you are a toddler or preschooler and have had some painful experiences on the potty, wouldn’t you avoid the potty the way you’d avoid any torture device? Painful experiences have trained the child to avoid the potty. I can only hope that the poor child’s caregivers aren’t adding to the child’s misery by punishing him for failing to use the potty.

Bowel movements aren’t supposed to hurt. If a child’s bowel movements are infrequent or difficult, there is something wrong. The usual cause of the problem is the diet.

Cow’s milk and other dairy products are a common cause of severe constipation in children. The digestion of casein, which is the major protein in cow’s milk, produces protein fragments that are called casomorphins because they have drug effects that are similar to those of morphine. Besides being slightly addictive, casomorphins can cause severe constipation. Fortunately, human beings do not need to consume any cow’s milk products at all, ever.

A low-fiber diet is also a common contributing cause of constipation in children. Animal-based foods all contain zero fiber, and refined plant foods contain very little fiber. As a result, the standard American diet, which is based on animal-source foods (including dairy products) and refined foods, is a recipe for constipation. It is also a major cause of appendicitis, which can be deadly. If all of the foods that a child is offered contain fiber, the child will eat fiber.

Often, a child’s refusal to use the potty is viewed as a problem with the child’s behavior. However, I think that when a child doesn’t poop for three or more days, it’s probably the caregiver, not the child, who is misbehaving. The caregiver is probably failing to feed the child the kind of diet that would enable the child to have normal bowel movements. Any healthcare professional who suggests drug treatments–even over-the-counter laxatives–or behavioral interventions without teaching the caregivers how to correct the child’s diet is also misbehaving, in my humble opinion.

Online course in nutrition from Cornell University

Cornell University is offering an online course in nutrition, under the supervision of T. Colin Campbell, PhD, a nutritional biochemist who is also one of the world’s foremost authorities on nutritional epidemiology. The course provides essential information for healthcare professionals (doctors, nurses, chiropractors, dietitians, nutritionists), patients, teachers, parents and anyone in the general public with an interest in reaching optimal health and dietary excellence. Medical doctors who take the course can get 19 Continuing Medical Education credits for taking the course.

Type 1 Diabetes: It’s the Milk, Not the Shots!

I was listening to a self-educated, self-styled health expert who was talking on the radio yesterday. He said something about some vitamin therapy for type 1 diabetes, and then he said something that shocked and upset me. He mentioned what he believes is the cause of type 1 diabetes. I expected him to say “cow’s milk.” There’s plenty of evidence to support the role of cow’s milk in causing type 1 diabetes. If more parents knew about the link between cow’s milk and type 1 diabetes, it’s likely that fewer children would come down with type 1 diabetes. Instead, he said, “vaccinations.” I’d never before heard of any link between vaccinations and type 1 diabetes, so I quickly did a MEDLINE search. I looked for articles on vaccinations and the cause of type 1 diabetes in humans. If you click on this link, you’ll see the same articles I did:


For me, this search yielded 60 articles, many of which I could read for free. By the time that you repeat this search, there may be more. Some of them were about the ability of vaccines to provide protective immunity in children who already had type 1 diabetes. Several articles were about the attempts to develop a vaccine to prevent type 1 diabetes.

One article pointed out that rubella infection was the only infectious disease that has been clearly implicated as a contributing cause of any form of type 1 diabetes. Of course, rubella could be completely eradicated, along with measles, if all of the world’s countries participated in a comprehensive vaccination campaign. Unfortunately, many people are refusing to get their children vaccinated against rubella because they are convinced that the MMR vaccine causes autism. I remember one woman in particular telling me that her child’s autism resulted from mercury in the MMR shot. I told her that I was sorry that her child has autism, but I can guarantee that mercury in the MMR shot had absolutely nothing to do with it. That’s because the mercury-containing preservative thiomersal has never been used in the MMR vaccine. I also explained to her that since congenital rubella infection is a possible cause of autism-spectrum disorder, then her efforts to scare people away from the MMR vaccine might make the problem worse, not better. If the world’s population worked together to eradicate measles, mumps, and rubella, then the MMR vaccine would no longer be needed.

The studies that looked for evidence of a statistical relationship between various vaccinations or vaccination schedules and type 1 diabetes kept coming up empty-handed. As the biggest and best-designed study concluded:

These results do not support a causal relation between childhood vaccination and type 1 diabetes.

If there really were some sort of cause-and-effect relationship, it would leave some evidence of its existence. In other words, we don’t have an absence of evidence, we have evidence of absence! There’s no rational reason to blame vaccinations for causing type 1 diabetes!

So far, vaccination campaigns have led to the complete eradication of two infectious diseases: smallpox and rinderpest. Smallpox is a human disease that was once a major cause of death and disfigurement. Rinderpest killed hundreds of millions of cattle. The next human disease that is about to be eradicated by vaccination is polioGuinea worm disease (dracunculiasis) is about to be eradicated by a campaign of education about sanitation. It is technically possible to eradicate measles, mumps, rubella by vaccination and lymphatic filariasis (elephantiasis) and cysticercosis (pork tapeworm) by other methods. There is even talk of eradicating malaria.

Nowadays, it’s no longer necessary to vaccinate people against smallpox. Soon, it will no longer be necessary to vaccinate people against polio. I look forward to the day when measles, mumps, and rubella are eradicated and the MMR vaccine will no longer be needed. In the meantime, there’s no need to worry that the currently used vaccinations pose any risk of type 1 diabetes.

no-more-measles-coverNote: Most of the people who build antivaccine Web sites and produce antivaccine documentaries have a profit motive. Some of them are faith healers who want you to put money in their collection plate. Others are selling overpriced vitamins and unproven herbal remedies over the Internet. Still others are providing some sort of service that has never been proven to be safe and effective. A few of them run nonprofit organizations that give them a salary. To get you to support them financially, they need to undermine your trust in your family doctor. For that reason, they attack the single most important service that conventional medicine can provide: immunization against serious diseases that do not respond well to any available treatment. I explain the history and motivations of the antivaccination movement in detail in my book No More Measles! The Truth About Vaccines and Your Health.