Search This Blog


Monday, November 28, 2011

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 includemeat 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. What makes meat valuable is the fat, not the protein. It’s 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.

Friday, November 18, 2011

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.

Wednesday, November 16, 2011

Pro Football Player Goes Vegan!

Dallas Cowboys fullback Tony Fiametta has reportedly switched to a purely plant-based (vegan) diet. He says that it makes him feel better on and off the field.

Tuesday, November 15, 2011

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.