Occasional ArticleNutritional characteristics of wild primate foods: do the diets of our closest living relatives have lessons for us?
Introduction
There is broad consensus that many chronic diseases affecting humans in modern technologic societies relate to diet.1, 2, 3, 4, 5, 6 Increasingly throughout the world, as traditional diets alter and become more Westernized, many of these “Western” diseases rise in frequency. In addition, other health problems, particularly but not exclusively in developing nations, often appear due to dietary deficiencies of one type or another.7, 8, 9
These findings make clear that there is considerable room for improvement in terms of human dietary practices. It is difficult to comment on the types of foods best suited for human biology because there have been and are so many different yet successful dietary patterns in the human species.10, 11, 12 As “cultural omnivores,” humans clearly can flourish on an extremely broad range of food items and cuisines.11, 12 In spite of this dietary breadth, it also seems clear that most humans, regardless of their culture or geographic locale, require the same basic nutrients to remain in good health, though types and proportions can vary depending on the sex, age, activity patterns, and other features particular to a given individual or population.9, 13, 14 Currently, for example, Americans are urged to eat more fresh fruits and vegetables and in great variety each day, and to lower their intake of sugar-rich foods and saturated animal fats.15, 16, 17, 18 However, there still remain many unresolved questions and conflicting opinions, even in specialist circles, about the best dietary practices for Americans.
Section snippets
Dietary reconstruction
To clarify what the best dietary practices for humans might be, one approach has been to attempt to “reconstruct” features of the diet of human ancestors.19, 20, 21, 22, 23, 24, 25 The logic behind such attempts often rests on the assumption, probably valid, that relatively recent changes in certain features of the human diet (e.g., cooking of most foods, heavy reliance on a single domesticated grain or root crop, selective cultivation to “improve” vegetables and fruits, consumption of highly
Comparative gut proportions of humans and apes
This comparative approach is particularly compelling because so much information is now available on the diets of wild primates as well as the evolutionary relationships between them. From these studies, we know that the extant great apes (chimpanzees, gorillas, and orangutans) are most closely related to modern humans, Homo sapiens.33 The ancestral line leading to extant chimpanzees and modern humans may have diverged as recently as 4.5 million y ago.33
When the human gut is compared with guts
Foods of wild primates
Primates are believed to have evolved in tropical forests and even today this is where most primate species are found.29 Indeed, the most recent paleontologic evidence suggests that the earliest known hominid (Ardipithecus ramidus—a taxon estimated to be some 4.4 million y old) lived in a closed wooded rather than more open savanna environment.41, 42 As forest dwellers, primates have found the foods available for most of their evolutionary history have been the leaves, fruits, and flowers of
Wild versus cultivated fruits
Domesticated fleshy fruits such as those purchased in American supermarkets typically have an attractive appearance, considerable succulent pulp, and few or no seeds. These fruits have been selectively bred for such characteristics and for a very sweet taste. They appear highly superior to their wild counterparts in the tropical forest, which tend to have a high seed-to-pulp ratio, a less pronounced sweet taste and, often an unappealing appearance (unpublished observations). However, most
Minerals
Micronutrients—minerals and vitamins—are rapidly moving into a prominent position in medical and nutritional circles. Many problems associated with malnutrition and child development in developing countries are now believed to involve an inadequate intake of energy or particular vitamins and minerals.7, 9, 70 Until recently, it was widely believed that protein or amino acid deficiency was responsible for the symptomology of chronic malnutrition in many developing nations.7 Careful analysis of
Vitamin c
Vitamin C is of particular interest in terms of human nutrition because, unlike most mammals that synthesize their own ascorbate internally, all anthropoids tested to date, including humans, lack the enzyme L-gulonolactone oxidase (GLO, EC 1.1.3.8), which catalyzes the final step in ascorbate synthesis from glucose.78 For this reason, monkeys, apes, and humans must ingest adequate vitamin C in the diet. The inability to synthesize vitamin C appears to be the derived condition since most extant
Fatty acids
There is strong interest in the types and amounts of fatty acids best suited for human health, and the percentage of daily calories that should come from dietary fat.4, 6, 7, 72 Analysis of the fatty acid composition of wild plant foods eaten by Panamanian monkeys showed the predominate fatty acids to be palmitic (30%), linoleic (23%), alpha linolenic (16%), and oleic (15%).83 Fatty acids with less than 16 and more than 18 carbon chains were uncommon (range 0–7%).83
Wild plant foods tended to
Protein and amino acids
Carpenter87, 88 has discussed the many misconceptions regarding protein requirements of humans, particularly misconceptions regarding the need for, or benefits of, large quantities of animal protein in the human diet. We now know that the average adult American appears to require somewhat less than 1 g of high quality protein per kg of body weight per day (0.75 g/kg average daily requirement for reference protein)15 to meet protein requirements.77, 81 When thinking of protein sources, tree
Dietary fiber
Cellulose and hemicellulose (along with pectin) are the major constituents of dietary fiber.63, 64, 106 Until recently, it was commonly believed that humans could not utilize the constituents of dietary fiber and for this reason there was no need to include them in the diet.106 No mammal, including humans, is known to produce enzymes that can degrade cellulose and hemicellulose. What many mammals including humans do have, however, are anaerobic bacteria and other gut flora in various sections
Conclusions and summary
Paleontologic, phylogenetic, and morphologic evidence indicate that modern humans come from an ancestral lineage in which the ripe fruits and young leaves of tropical trees and vines are likely to have played a key dietary role. Analytical data suggest that many of the wild plant foods monkeys and apes currently consume differ in some respects from many cultivated fruits and vegetables eaten by humans. In contrast to humans, wild primates also take a high percentage of the daily diet from
Acknowledgements
Particular thanks to K. J. Carpenter for his interest and advice regarding preparation of this paper, to S. Turner for his help with figure and table formatting, and to two anonymous reviewers for their useful suggestions.
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