About 9,000 years ago our ancestors started to domesticate wild grasses. From these we get the cereals we know today: wheat, barley, maize, rice. We could not eat them directly as the starch molecule is too large for our digestive process to cope with.
It had to be broken down first by cooking. This development began a dramatic change in Man’s lifestyle. Once our ancestors produced controlled quantities of higher-energy starches which could be stored, their numbers could grow. And as numbers grew, it became more difficult to maintain their supplies through hunting. Thus their basic diet changed from a high protein/fat diet to one largely of carbohydrate.
This radical change of diet brought with it radical changes to our ancestors, both in physique and in health.
As vegetable foods made up an increasing proportion of our diet and intakes of meat declined, so our height also declined. European, meat-eating Homo erectus erectus of 30,000 years ago was some 150 mm (6 inches) taller than his agricultural descendants. Indeed, even today we are still shorter than they were. We see the same pattern in North America. The Paleoindian hunters of 10,000 years ago were much taller than their farming descendants at the time of European conquests of the fifteenth and sixteenth centuries AD.
There is no evidence of nutritional diseases before the advent of agriculture. After it, there is. The cereal crops that became the modern staples, together with root crops that began to be cultivated, are all relatively deficient in protein and the B vitamins.
Additionally, all the cereals contain a substance called phytic acid that binds with a number of minerals and other nutrients and reduces their availability to the digestion. As a consequence, with the coming of agriculture we see the appearance of a number of nutritional diseases such as rickets, pellagra, dental caries, beriberi, obesity, allergies and cancers. We see the emergence of the ‘diseases of civilization’.
About two hundred years ago there began a second dietary revolution which was brought about with the introduction of industrialization. This had two powerful but opposite effects on our health. The industrialized countries with their increased wealth no longer had to rely on home-produced food with its seasonal changes, they could import the food they needed.
Thus the populations of those countries could look forward to going through life without ever being hungry. A good thing, you might think, but it brought with it adverse effects.
Many of the imported foods were unnatural to those eating them. The new fruits, in particular, as well as being novel, tasted nice. As a consequence, we changed from eating what we needed to eating what we liked.
And with no previous experience of these foods, our bodies had never learned when to stop. Subsequently, science made possible the production of synthetic foods that had the appearance, texture and taste of the real thing, but with none of the proteins, minerals and vitamins.
Sugar, which contains no useful nutrients whatsoever, became easy and cheap to produce, leading to a 30-fold increase in its consumption.
The industrial revolution, therefore, was something of a two-edged sword. On the one hand it gave people a wider range of nutritious food than had ever before been possible; on the other hand it brought diabetes, peptic ulcers, heart disease and yet more dental caries, cancers and obesity.
In the late twentieth century the speed at which our diet has become increasingly unnatural has quickened. When a music-hall singer at the beginning of the twentieth century sang that ‘a little of what you fancy does you good’, there was still an element of truth in it - at least as far as diet was concerned.
When hunger signaled that the body needed more nourishment, appetite determined which elements. At one time, we ate what we had an appetite for, and the body’s needs were met. Nature told us what to eat and by this means, nature ensured that we ate a balanced diet.
Over the last two centuries, and increasingly during the last several decades, however, the situation has changed dramatically.
During the millions of years that we have been evolving, we have been eating our natural food. We had a sense of taste that told us what was good for us and what was poisonous. Like all animals on this planet, we ate what we liked without danger either from nutritional deficiency or from overindulgence. But when food is changed from its natural state that no longer holds true.
At first, all our food, whether from animal or vegetable sources, was eaten raw. Now cooking food has become a way of life. Most people in Western society today would not eat uncooked meat. Indeed, as possible pathogens would not be killed, it may be unwise to eat raw meat.
But, while boiling parallels the first stages of digestion, and may be helpful in that process, over-cooking in a way that chars food can present the digestive processes with food which it has great difficulty digesting.
In 1838, in Canada, Dr. William Beaumont performed a remarkable series of experiments on a man named Alexis St. Martin. St. Martin had an opening in the front wall of his stomach from a gunshot wound.
Even after the wound had healed, there remained a small opening through which the mucous membrane of his stomach could be seen and, through which, substances could be introduced into the stomach or removed from it. Dr. Beaumont was able to introduce foodstuffs through the opening and observe the rate of digestion.
By so doing, he found that raw beef digested in two hours, well done boiled beef in three hours but well-done roast beef took four hours. Similarly, raw eggs were digested in one-and-a-half hours but hard-boiled eggs took three-and-a-half hours.
In contrast, the cellulose which envelops cereal grains and which is the major constituent of vegetable cell walls, cannot be broken down by the digestive juices at all. Only the process of cooking ruptures them.
Cooking is also the only means of breaking down the large starch molecules so that we can digest them. As a consequence, cereals and many other vegetables need not only to be cooked, but well cooked, before they can be digested.
That is not to say, however, that cooking presents no other problems. Cooked food, for example, can be damaging to the teeth. We know that sugar is a major cause of cavities in teeth, particularly children’s teeth.
We also know that the effect is worse if the sugary food is sticky. Dates and toffee are both high in sugars and stick around the teeth. Both, therefore, might be expected to cause cavities. But while toffee does cause dental caries, Arabs who eat sticky, sweet dates have healthy teeth. Why the difference?
All living organisms have immune systems that protect them from invading bacteria. At the time of being eaten, the raw dates are still living organisms and their immune systems are working. The bacteria that would ferment the sugars in the dates and form the acid which attacks teeth, are repelled. That is not the case with cooked and, therefore, dead toffee.
Cooking can also destroy some nutrients: Vitamin C is a good example. Thus nutrients, which might be present when food is ‘natural’, are lost and their correct balance may also be lost.
Cooking food, therefore, may cause changes to which the body’s systems are not entirely adapted and which, as a consequence, may cause us minor problems.
Today, however, food has been changed much more radically and in a shorter time span - a time span much too short for us to have evolved and adapted to it. A large proportion of the food we eat now can no longer be called natural. This is particularly so in the case of carbohydrates - sugars and starches. There is a considerable body of evidence that it this change which is the cause of so many of today’s ills.
There are a number of vegetable-based foods that are processed to such a high degree that nothing but pure carbohydrate is left. The obvious example is white, granulated sugar.
Sugar cane and sugar beet contain a significant proportion of protein that is lost during processing. Also lost are other nutrients such as vitamins and fiber. The end product is pure, concentrated carbohydrate. It is this concentration that is so unnatural. This has not happened with protein as it is relatively expensive.
Neither has it happened with fats as they are already concentrated naturally. The concentration of carbohydrate allowed a dramatic and rapid increase in its consumption. Annual sugar consumption in Britain in the middle of the eighteenth century was less than two kilograms (4½ lbs) per person, today it is more than sixty kilograms (130 lbs).
The same is true of cereals, albeit to a lesser degree. Many packaged foods today contain what is euphemistically called ‘modified starch’.
This again is highly concentrated carbohydrate, in this case cereal starch. This concentration of sugars and starches is done to make foods cheaper, more attractive and, of course, to make a bigger profit for the manufacturers. But it has had serious effects in large sections of the population.
The body’s natural nutrient-requirement signal, the appetite, has not evolved to cope with such unnatural foods. It knows when to stop us eating meat, but not when to stop us eating chocolate bars and cakes. It is also much easier to eat modern white bread than the stodgy, pre-Industrial-Revolution bread.