The mandates of human physiology
The Heritage Factor explains the changing human foods and eating habits from the viewpoint of our genes and physiological conditioning. How biological and social evolution of our species have affected both our foods and dietary habits, but also and inevitably our health and disease patterns [1]. This is a field of research initiated by Dr. Connie Phillipson, with Ph.Ds in both prehistoric archeology and nutrition. Her researches have shown that many of our disputed theories and challenging assumptions, such as the theory of blood groups, the Glycemic Index of foods, and so on, are not simply modern observations assembled into theories, but basic mandates of human physiology and biochemistry, with deep roots into our distant past.
Therefore, the study of humanity's nutritional and environmental history can be a key to grasping the infrastructure of human health, and the flaws responsible for disease. But the challenge is formidable and the difficulties many. Thus for example how do we know what our distant hominid ancestors ate in the African rain forest? A frequent answer is whatever the other higher primates still eat: the leaves, flowers and fruits of the forest. But the rain forest contains some 3000 foods, while the stools of Madagascar lemurs showed the spores of just over 200. There is obviously room for choice here, and room for errors. Besides, why did our ancestors leave the rain forest, an ideal environment for primates without tools, implements, utensils or weapons, while all the other higher primates are still there? Most theories about such questions are a little vague, a lot more imaginative, and totally unsubstantiated. (For more on the subject of our ancestors' diets, click ANCIENT NUTRITION)
Depressingly few facts
Theories are valuable when they are based on facts. But when it comes to the diet and eating habits of our hominid period, facts are depressingly few and likely to remain so for a long time. The usual probes, such as excavations, are of not much use in today's rain forest or that of earlier times. The high acidity of forest water would prevent the survival of organic remains for more than a short time. Other research such as the traces left by food-staffs on primate teeth, may not be as reliable as we first thought, because the marks we distinguish may be only those of the last foods eaten, not necessarily of their overall diet, and so on.
That is why when we developed the research lines for The Heritage Factor we reversed the normal research procedure. We looked at human physiological and metabolic functions to learn what and how our distant ancestors ate, instead of the other way around. This may seem odd at first, but it turns out to be the only secure alternative we presently have. Do you want an example? Nutritionists have been aware for sometime now that certain basic nutrients interfere in each other's absorption. Thus although we have no trouble absorbing from the flesh of animals both protein and fat, two very different nutrients, calcium interferes in iron absorption. But this seems bizarre considering how important both elements are for us, and that there has been ample time in the making of our genetic code to have developed mechanisms for absorbing one in the presence of the other, as is the case with protein and fat. Why doesn't fat interfere with the absorption of protein from the flesh of animals, but iron and calcium should interfere in each other's absorption? No explanation for this strange antagonism has been advanced until now, save that "this is how it is in nature." Only this is no explanation, but a simple cop-out. One could say the same thing about anything. On the other hand, a look at the principal sources of calcium and iron in today's foods, in milligrams per 100gr and obtained from a modern reference [2], is bound to clarify matters.
Calcium in foods |
||||
| Hard cheeses |
1200
|
Legumes (beans) |
150
|
|
| Eggs |
60
|
Soft cheeses |
725
|
|
| White flour, fort. |
140
|
Cereals |
60
|
|
| Canned fish |
400
|
Cow's milk |
120
|
|
| Fruit* |
60
|
Nuts* |
250
|
|
| Root vegetables* |
80
|
Wholemeal flour |
40
|
|
Iron in foods |
||||
| Cockles* |
33.0
|
Cooked liver* |
12.5
|
|
| Parsley |
8.0
|
Brewer's yeast |
20.0
|
|
| Cooked kidney* |
11.5
|
Dried fruit |
5.8
|
|
| Winkles* |
15.0
|
Cocoa powder |
10.5
|
|
| Cereals |
4.1
|
Wheat bran |
12.9
|
|
| Soya flour |
8.0
|
Beef* |
1.9
|
|
Different dietary activities
Of the 12 listed foods under calcium, only nuts, root vegetables and fruit (marked *) could have been eaten by our Stone Age or earlier ancestors. The rest were simply not available to them. Of the 12 iron foods, only the internal organs of animals, their meat, and in certain circumstances cockles, winkles, and other mollusks, might have been the main sources of iron. But nuts, root vegetables and fruit are the products of foraging. The internal organs and flesh of animals come from scavenging or hunting. Only these are different activities associated with survival, which could not be pursued at the same time. When our hunter ancestors scavenged or killed some game, they assembled at the site or some nearby bivouac and ate all the meat they could. That is because they knew they could not store it. Left meat would soon become unavailable, either because of its tendency to rapidly spoil under the African sun, or because it was bound to attract some other fierce predators. This left little time for foraging, which was in any way unnecessary when a meat supply was available.
It is true that mollusks may be also the products of foraging, but they would be found in different areas from these of plant foods. In short, the living conditions of our ancestors and their immediate environment obliged them to separate carbohydrate foods from animal proteins and fats in their everyday meals. Not as a matter of choice, a conscious nutritional alternative, but a simple necessity--the stark needs of everyday existence.
Thus it seems that the main reason why over millions of years we did not develop a better absorption mechanism for iron in the presence of calcium, is that this was not needed. The lifestyle of our distant ancestors made it unnecessary. This is one instance out of scores of examples, illustrating the special circumstances that obliged our ancestors to pursue certain practices vital for their survival, the outcome of which ultimately became established in their genetic code, and subsequently and inevitably into our own.
For more on the subject, see reference [3] below, and click NUTRIENT PARTITION
REFERENCES
- Phillipson C 1997. Paleonutrition and Modern Nutrition. World Review of Nutrition and Dietetics 81:38-48
- Mervyn L 1989. Thorson's Complete Guide to Vitamins and Minerals. London.
- Phillipson C & J 1998. A Testament of Savagery: The Folly of Balanced Meals. [The Roads of Food Habits in the Mediterranean Area. 7th Meeting of the International Commission on the Anthropology of Food, Naples, May 26-30, 1997]. Rivista di Antropologia 76 (Suppl):283-292. See especially the section, Food habits of our ancestors, pp. 285-7.