Our
Prehistoric Beginnings.
Human evolution has been
underway for between three and four million years. During that time our bodies
and internal organs have developed and changed relatively little. So our digestive
system still functions best with the diet consumed in prehistoric times.
For
maximum health and longevity our diet should conform as nearly as possible to
that in the Stone Age.
Most
wild animals stay sleek and healthy and do not become obese, even when food is plentiful. This is
true even for animals kept in zoos. Domestic animals, particularly dogs and
cats, only become obese when they are fed the wrong diet, such as introducing
cereals and other carbohydrates to their meat diet.
Humans are omnivorous. Our dental pattern most
closely resembles that of the apes, like chimpanzees and gorillas. Their diet is
mainly fruits and leaves, occasional insects and small animals and rarely meat
from larger animals.
Our digestive
system points towards a mainly herbivorous diet, not mainly meat. Our
saliva contains an enzyme called ptyalin, which is for the pre-digestion of
starch, which is lacking in carnivores. The concentration of stomach acid is
lower than in carnivores and our intestines are much longer, for the digestion
of plant materials. Finally, humans do not possess the ability to convert uric
acid, derived from dietary protein, to the more soluble allantoin. High levels
of uric acid in humans are associated with the painful arthritic condition gout.
The anatomy of humans resembles
that of the great apes. Stereoscopic vision is better suited for delicate hand
eye coordination, for picking fruit off trees, and our colour vision is best in
the red /green range which helped find ripe fruit. Man is unique in eating cooked food and
finds uncooked meat and fish
unpalatable, however Man would not have had regular access to fire prior to
7,000 BC.
A key aspect of human physiology
which points towards a diet heavily reliant on fruit and vegetables, rather than
meat, is our lack of ability to synthesis vitamin C. Man, together with one or
two mammalian species is unique in not manufacturing vitamin C, one of the most important
vitamins. This suggests that we existed on a diet of fruit and vegetables, high
in vitamin C, and therefore didn’t need the ability to manufacture it. Now,
vitamin C is one of the main supplements taken in Western societies.
It could be argued that a
vegetarian diet is not sufficient to produce a strong and healthy body, that a
high meat diet is required for strong muscles. But we shouldn’t forget that
the biggest, strongest animals, like elephants and oxen, are herbivorous. Our
own growth rate is greatest in the first five months of life; yet human breast
milk is only 10% protein.
Modern man is now accustomed to
readily available food, high in fats and protein, mainly processed, which
destroys much of the nutrients. The evolutionary necessity to gorge on food when
plentiful, to safeguard against times of famine, is still present to the extent
that we eat constantly, not for purposes of nutrition, but for entertainment and
as a distraction. Consequently, the unsuitable diet contributes directly to the
increasing incidence of human diseases, such as cardiovascular (caused by high
animal fat diet), cancer (linked to high animal protein diet and deficiencies in
antioxidant vitamins), diabetes (high sugar diet) and obesity (too much food and
not enough exercise).
This
article is based on the paper ‘The nature and importance of our prehistoric
diet’ by Allan Withnell Nutrition and Health 2004; 17:269-273.
