A cat or dog salivates with anticipated pleasure at the sight and smell of raw meat, but very few humans exhibit this behaviour. For most meat eaters, their chosen cut needs to be cooked before it becomes attractive. This is just one factor that might make us wonder whether eating meat is natural for us, and whether being a vegetarian is a realistic option.
Other clues can be found by comparing the anatomy and physiology of humans with different types of animal. It emerges that humans are far more similar to fruit and nut eating animals – vegetarians such as monkeys and apes, and to leaf and grass eating animals such as sheep, cattle, elephants and koala bears, than to the carnivores.
The following two lists show the characteristics, first of carnivores, and then of non-carnivores, or vegetarians.
- Have very short digestive tracts (three times their body length) to excrete decaying meat waste rapidly.
- Produce very strong stomach acid – typically 20 times stronger than that of a non-carnivore – to digest bone, sinews and large quantities of meat.
- Produce small amounts of saliva because digestion does not begin in the mouth with carnivores.
- Tend to have jaws that can only move up and down, which means that they cannot grind their food and can hardly chew at all. Meat is torn off with their long, sharp incisors and canine teeth, and is swallowed in large chunks. The teeth are also shaped and angled to move with a shearing motion to cut through bone and tough sinews.
- Show great agility in catching prey, and have sharp claws and strong jaws to bring down, kill and consume prey.
However, vegetarians – non-carnivorous animals and humans generally:
- Have long digestive tracts that are about the same proportion to body length as in grass-eating animals (12 times). The great length allows the longer period of time that is needed for fruit and vegetables to be digested completely.
- Have weak stomach acid, which is all that is necessary for the slow digestion of grasses, grains and vegetable matter.
- Produce a larger quantity of saliva, which also contains the enzyme ptyalin. The plentiful saliva and the ptyalin begin the digestion of grains, fruit and vegetables in the mouth. Carnivores neither eat these kinds of food nor do they chew their food, which means that digestive enzymes in their saliva are absent.
- Have jaws that move with a grinding motion. This grinding together of the relatively flat teeth reduces the particle size of the food and exposes it to the saliva and ptyalin in the mouth. Human canine and incisor teeth are small compared to those of a carnivore and are, perhaps, better suited to biting tough vegetables rather than animal skin and bone.
- Have no claws, relatively weak jaws and not a great deal of agility. For example, if a chicken is placed in an open space it would be extremely difficult for a human to catch it; we don’t appear to be designed for that sort of activity.
The evidence seems clear that humans have evolved to eat little or no meat – to be vegetarian.
Is meat actually harmful?
Many people eat meat and appear to survive reasonably well. So why shouldn’t humans eat meat if they want to? Why should they be vegetarian? There is the moral objection that animals should not be killed for the benefit of humans. This argument is complex because, for example, few people go so far as avoiding shoes and gloves made from leather – and most of the arguments that apply to leather also apply to meat. However, leaving the moral argument aside, there is a very strong reason not to eat meat – it is bad for our health.
Meat makes disease more likely
Clearly, humans have not evolved to live primarily on a diet based on animals – they are natural vegetarians. Dogs, for example, can eat solid blocks of butter and still keep their blood cholesterol levels stable despite the massively increased intake. If humans markedly increase animal fat consumption, such as butter, the level of cholesterol in the blood rises. In the long term, cholesterol makes artery and heart diseases almost certain, and death from one of these causes is highly likely.
Cholesterol consumption is not the only factor making degenerative disease more likely. Another factor that contributes to cancer development may be the presence of chemicals in meat. It is generally accepted that when pesticides and other chemicals are consumed they become concentrated in the body’s fatty tissue. This happens in animals as well as in humans.
If food animals eat vegetation that is contaminated with pesticides or chemical fertilizers, or with industrial toxins such as cancer-causing dioxins, traces of these chemicals are deposited in their fat and throughout their muscles, which are partly fat as well. If we then eat meat from these animals, we also eat these chemicals – and in a relatively concentrated form. This argument also applies to the consumption of fish, much of which has been exposed to industrial waste which pollutes river and the seas. For example, contamination of fish with the deadly poison mercury is widely reported in research.
The New England Journal of Medicine reported a study in which mothers’ milk was tested for chemical residues. The highest levels of residues were found in the milk of meat eaters, and the lowest levels in vegetarians. More significantly, the least contaminated breast milk from a meat-eater still contained more contaminants than the most polluted milk from a vegetarian mother. This indicates that, for this factor at least, vegetarianism is healthiest.
Testing has established that industrial toxins are present in only small amounts in vegetables, fruit and grains, and are found at much higher levels in meat and dairy foods (cheese, milk and eggs).
There is strong evidence to suggest that we humans have not evolved to eat high proportions of meat in our diets, and that doing so significantly increases the likelihood of developing cancer and heart disease. If you are not a vegetarian, you will be healthier and probably live longer if you ate less meat. Therefore it is recommended that a vegetarian diet is followed and meat intake is reduced to help ensure long-term health.
The extensive China- Cornell-Oxford study of cancer incidence, which began in the early 1980s, found that the average meat-eater in the US is 17 times more likely to die from heart disease than a person getting only 5% of their protein from meat sources. Furthermore, women in the former category are five times more likely to develop breast cancer.