What is the natural diet for humans?

A frequent question is “what is the natural diet for humans?”

William Roberts is a leading cardiovascular pathologist.  He is the current editor of the American Journal of Cardiology – a position he has held since 1982.  He has written over 1,500 articles, a number of books and editorials for the Cardiology journal.

Dr Roberts wrote an editorial We think we are one, we act as if we are one, but we are not one 1 in the Cardiology journal.  He was referring to us thinking that we are “carnivores”. His conclusion is:

Thus, although we think we are one and act as if we were 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, which are natural herbivores.
Let’s compare our anatomy with real carnivores. Our canine teeth are canine only in name. A real carnivore (like your cat and dog) has razor sharp canine teeth designed for ripping and tearing.  Our molars a large and flat designed for grinding fibrous plant material. The jaws of a carnivore move up and down – they tear the food and swallow it whole.  We can move our jaws up and down and side to side to ground the food.

Our intestines are much longer in comparison to carnivores. A carnivore intestine is 3 – 6 times the body length whilst humans are 10 times. All animal proteins produce carcinogenic compounds – even more so when cooked. Therefore, the least amount of time it is in the carnivore’s body the better. Animal proteins also produce opiates which probably explains are addiction to meat.

And our hands – try wrestling a pig to the ground with your bare hands and making a meal of it. Yes, it may sound appealing but if you actually try it – it is not really practical.  These are dexterous hands of a food gatherer – not the claws of a hunter.

Harvey Diamond writes – “Put a small child in a crib with a rabbit and an apple.  If the child plays with the apple and eats the rabbit, I’ll buy you a new car”. 2

We are simply not designed to eat rabbits, pigs or any other creature that can hop, walk, swim or crawl.

If you doubt that a whole food plant-based diet is our natural diet then consider this. When you see dead kangaroo on the side of the road, are you tempted to stop for a snack?

Is Natural Good?

It is however, misleading to believe that anything natural is inevitably good. It is natural for humans and chimpanzees to kill others. Gorillas, orangutans and bonobos are not nearly as aggressive.

The other issue is that creatures evolve based on behaviour. Giraffes have long necks because antelope-like ancestors used their necks to fight and males with the longer necks are more likely to win and reproduce. Long necks make life difficult when it comes to drinking water at a waterhole.

It is not natural for mammals to drink milk after weaning. Most people lose the ability to produce lactase by the age of 7. Lactase is an enzyme required to digest the sugar lactose which is found in milk. People who are lactose intolerant and drink milk can result in intense discomfort.

Dairying 3 dates back to at least 8,500 years ago from the Middle East in the fertile region of the Tigris and Euphrates rivers. By 7,500 years ago, the ability to digest milk as an adult, lactase persistence, was present in the regions of Hungary and Poland. A thousand years later, lactase persistence reached northern Germany and by 5,000 years ago was prevalent in central and northern Europe.

In addition to Europe, other areas that have populations that are lactose tolerant include central Arabia which is related to the domestication of the camel, a region surrounding Gujarat, the north-western coastal state of India and a region surrounding Senegal in western Africa.

Creatures evolve based on behaviour and an advantage of a trait in one aspect may be compromised by a negative impact elsewhere.

Our Diet Compared with Chimpanzees

Chimpanzees chew food for up to 6 hours per day in order to digest their fibrous diet.  According to Katharine Milton 4, fruits comprise of 88.5% – more than 95% of the chimpanzee diet. Cooking allowed food to be more easily digested. According to Richard Wrangham 5, humans have small mouths and lips, weak jaws, small teeth, small stomachs, small colons, and smaller intestines compared with chimpanzees because of the use of fire and cooking.  It is easy to argue that cooking is not natural. However, all societies rely on cooking and it is an essential part of human life – not a luxury.

Another big difference is that humans have significantly more amylase in our saliva than chimpanzees. Amylase is a group of enzymes that allow starches and glycogen (a carbohydrate found in meat) to digested. Creatures evolve based on behaviour – a behaviour becomes “natural” because of repeated repetition and does not necessarily mean that it is in our best interest all aspects of our lives.

See the post How Cooking Changed Us for more information regarding the effects of cooking.

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  1. Roberts, W. C. (1991) We think we are one, we act as if we are one, but we are not one. American Journal of Cardiology. 66 (10), 896.
  2. Diamond, H. & Diamond, M. (1999) Fit For Life. New York: Harper Collins Publishers.
  3. Curry, A. (2013) The Milk Revolution. Nature. 500.
  4. Milton, K. (2003) Micronutrient intakes of wild primates: are humans different? Comparative Biochemistry and Physiology.
  5. Wrangham, R. (2008) Catching Fire: How Cooking Made Us Human. Basic Books.

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