Meat in the diet of man.

Abstract

MEAT IN THE DIET OF MAN N.A. MACDONALD* SUMMARY Meat has traditionally held an important role in man's diet and culture. Our earliest truly modern human ancestors' life and religion centred around the search for large game which formed the basis - and often the major component of his diet. The of for was pressure of increasing population density coupled with the disappearance many species of large game animals forced man to seek other alternatives food. A more varied diet including many more plant foods developed and assisted eventually by the advent of agriculture some 10,000 years ago. No culture throughout man's history has ever been totally vegetarian, though diets containing up to 90X meat are not uncommon. In general anthropological evidence indicates that populations who had access to a variety of animal protein sources were healthier than those whose diet was restricted to plant foods alone. The past extremely compared and which 100 years - a mere dramatic change in to those which our are still consumed moment in our evolutionary history - has seen an the composition of the average western diet ancestors consumed for tens of thousands of years by traditional hunter-gatherer populations today. The high fat content of meat available to consumers today compared to traditional wild meats has contributed to the total increased fat content of the western diet. This contribution is only small considering the range of pre-prepared and processed foods available today, many of which are high in fat and the fact that meat fat is visible and thus relatively easy to avoid. However, I believe meat producers have a responsibility to minimise the production of excess fat on animals and maximise production of nutrient dense, lean meat. DISCUSSION While humanity has existed as a genus for about 2 million years, the first truly modern human beings &VTW sapiens, only appeared about 40,000 years ago. Over this time the human genetic constitution has changed very little: Agriculture aed modern food processing are far too recent to have had any evolutionary effect at all. Thus, essentially the nutrition for which man is genetically programmed is little different to that of our preagricultural ancestors. The range of diets they consumed determines the range that still exists for we 20th century dwellers. * Australian Meat & Live-stock Corporation, Sydney, NSW 2000 5 Before the advent of agriculture some 10,000 years ago, man% quest for food centred mainly around meat - this was procured either by hunting or scavenging or a combination of both. &VW sapiens was omnivorous and supplemented Ns diet with whatever plant foods available - mainly nuts, berries or fruits. (Abrams, 1980) The number of plant foods he could eat however was limited because many had to be cooked to be edible. All contemporary hunter-gatherer societies (eg: aborigines) cook the majority of the wild plants they collect for food. The majority of modern staple plant foods - rice, corn, wheat, legumes and fiber crops like taro and potato - must be cooked to render them non-toxic and/or digestible. Thus the discovery of fire and the mastery of the art of cooking - which only occured about 50,000 years ago meant that a great variety of plant foods could be added to the diet. (Leopold & Audrey, 1972) (Interestingly, there is evidence of the use of fire by late H. erectus for some 50,000 years at least before it was actually widely used for cooking). Eaton & Konner (1985) provide a timetable of the main events in human evolution which gives an overview of what is presently known about our ancestor% dietary habits. (Table 1) While our hominid ancestors consumed some small animals along with insects and plant food, the development of stone and later more advanced tools parallelled a move towards a diet containing more meat. Abrams (1980) suggests that it was our Paleolithic ancestors' reliance on meat as a major source of food which had the greatest impact on promoting the evolution of the human species. Meat is a much more concentrated and efficiently utilised form of many nutrients than plant foods. A full day's foraging is likely to be necessary to obtain the amount of food value in one small animal. However, utilise rodent, canines humans are not carnivores - Humans are unique in their ability to a huge variety of foods. Humans have the cutting incisors of a the grinding molars and premolars of a herbivore and the pointed of a carnivore. man's omnivorousness has despite calamities such as to thrive in a huge risk of starvation. Peter Farb and George Armelagos (1980) suggest that allowed him to be able to supply his nutrient needs pests, floods, fire and famine. It also allows man variety of environments and to travel widely without However, man is successful as an omnivore largely because of his higher intelligence allowing him to distinguish between and remember 'good' and 'bad' foods. Abrams (1979) points out that no culture in the history of mankind has been based on a totally vegetarian diet. Conversely however, diets based almost totally on meat and animal products are quite common - even in recent times as in the case of Eskimos. 6 Man's reliance on meat as a back as 3 million years ago process animal foods. The for processing plant foods food is evidenced by fossil remains from as far of butchered animals and tools used to secure and first evidence of the development of tools designed comes much later - around 20030,000 years ago. sapiens, For Homo erectus and the early Homo hunt for large game (Abrams, 1980). daily life revolved around his However, plant foods still probably made up more than 50% of the diet (Isaac & Crader, 1981) at this stage. When Cro-Magnon man and other truly modern humans appeared big game hunting increased (Eaton & Konner, 1985). At this time (45,000 - 70,000 years ago) the human population was still small compared to the available prey and hunting technology was well advanced. Cro-Magnon man's life, religion and magic all centred around the hunt for large game (Eaton & Konner, 1980). This is most obviously evidenced in his cave art which shows many of the types of animals eaten - including bison, bear, horse, woolly mammoth and deer. The quest for game was also the force which compelled Cro-Magnon man to move to previously unpopulated and climatically less desirable parts of the world like Alaska and Siberia. While Cro-Magnon man no doubt consumed a variety of plant foods, it is likely that in many areas meat provided 50% or more of the diet at this time. In areas like Alaska he had to rely almost entirely on meat. However, Cro-Magnon and our other progenitors effectively hunted many species of large game to extinction (Martin, 1967) over the next 30 to 50 thousand years and gradually there was a move away from big-game hunting to gathering a wide variety of other foods. Although there is evidence of fish and shellfish being consumed around 80,000 years ago, it is at this time (immediately before the agricultural revolution - around lO-l2,000 years ago) that fish and shellfish are thought to have been more commonly included in the diet. It was also this period which saw the development of early grinding type tools for plant foods (Eaton & Konner, 1985). With the supply of game struggle for survival and the domestication of to agriculture only from the greatest effect. exceedingly depleted.humankind faced its first real a struggle which resulted in the advent of agriculture animals. Abrams (1980) contends that humans turned necessity - it is pressure of population which has The amount of animal food consumed by any culture however, depends largely on availability. Apart from religious groups and other small sections within different cultures, most people will eat animal food when it is available. Marvin Harris (1985) notes that most (predominantly) herbivorous modern cuisines are associated with dense populations whose habitat and food production technology cannot support the production of animals for meat without reducing the amount of protein and calories available for humans. In contrast most (predominantly) carnivorous cuisines are associated with relatively low population 'densities and lands generally unsuitable (or not needed) for cultivation. Certainly historical evidence supports this relationship. However, vegetarianism does exist even within populations where meat is quite readily available. For example, Trappist monks abstain from meat because they consider it to be a luxury that is incompatible with their vows for a simple way of life (Abrams, 1980). In fact, Abrams (1980) points out that the prohibition of eating meat or certain types/combinations of meat is not health related in any traditional religion or sect. fl At our present fairly advanced state of knowledge of human nutrition, it is theoretically possible for one to obtain all the essential nutrients from a completely vegetarian diet by carefully balancing the intake and combination of plant foods. bwever, it is still difficult for most people to achieve as it does require a faPrly indepth understanding of nutrition or some training in combining and selecting different plant foods. There are of animal vegetarian restricted some cultures who have protein, but in general advocates - historical access to animal foods effectively managed on extemely low intakes - and often contrary to claims made by evidence suggests that peoples who have had were less healthy. The shift from Cro-Magnon man's diet containing around 50% (or more) meat to one containing up to 90% vegetable sources with the advent of agriculture had profound morphological consequences. Eaton & Konnor (1985) report that the early Furopean Homo sapiens s@ens who enjoyed an abundance of animal protein 30,000 years ago, were an average six inches taller than their descendants who lived after farming. In addition, Nickens (1976) notes the same pattern among Paleoindians in America. lhey were big game hunters 10,000 years ago but their descendants just before European contact practiced intensive farming, ate little meat and were considerably shorter in stature. There is also evidence that they had skeletal manifestations of suboptimal nutrition related to protein - energy malnutrition (Abrams, 1980). New World cultures such as the Inca of South America and Aztecs of Mexico combine consumption of maize (corn) with beans to compensate for a lack of animal protein in the diet. However, they did not depend exclusively on this combination, utilising any animal protein they could as it became available. They consumed fish, guinea pig, duck, turkey, worms and some species of native dog among others. In many cultures - including the Aztecs - religious human sacrifice was also common and some anthropologists believe that the victims were eaten to satisfy the desire for animal protein- (Harris, 1977). It is interesting that in societies where a ruling class existed there was marked variation in health status between the classes. For example Abrams (1980) quotes anthropologist William Haviland's study of the Mayan civilisation: it seems the ruling class, who supplemented their diet with the few animals foods available, enjoyed better health than the rest of the population consuming mainly corn and beans. The ruling class were significantly taller (170 cm vs 157 cm) and lived longer than the masses. 9 In areas where the population density dissallows extensive livestock production, some societies have domesticated animals in order to be provided with milk to increase the animal protein content of their diets. In societies where lactose is not tolerated, fermented milk products are often used. However, milk and milk products are not regarded as appropriate food for a large proportion of the world's population for other reasons. One good example is China where milk drinking is widely regarded as we might look upon the drinking of blood. In terms of the nutritional status of whole populations, the Industrial Revolution saw the beginning of a move back towards increasing the animal protein content of human diets. One reason why we are now nearly as tall as were the first biologically modern human beings may relate to the increased protein content of the diet. (Eaton & Konner, 1985). However, our diets still differ markedly from theirs. In a short 100 or so years (an extremely short time in evolutionary terms indeed!) the fat content of the average Western diet has increased greatly while the fibre content has decreased. At the same time labour-saving devices and readily available transport modes have reduced exercise levels to minimal for most people. The domestication of .meat-producing animals (particularly cattle, sheep, pigs and chickens) and subsequent advances in production have contributed to the increased fat content of the Western diet. I believe that their contribution is consistently over-emphasised, due mainly to the misuse of domestic dissappearance based data in assessing the contribution made by red meat to the fat content of the diet. Only a very small amount of the fat originally present on actually purchased or consumed as meat itself (Fantini & However, some of the fat originally present on the carcase in preparation of retail cuts re--enters the food supply as industrial margarines used in processed food manufacture. an animal carcase is Macdonald, 1987). which is discarded edible tallow or Thus, if the total fat content of beef and lamb carcases was reduced at the production end of the chain, the total amount of this source of saturated fat in the diet would also be reduced - something which I believe could only benefit us nutritionally. The diseases of affluence which have emerged in the past 100 years are dominant health problems in Western countries but are still virtually unknown among the few surviving hunter-gatherer populations. Modern day hunter-gatherer societies maintain similar lifestyles to our ancestors. 10 Grin OWea and Andrew Sinclair (1983) in Melbourne have analysed a number of wild animals still used as food by traditional aboriginal communities in Australia (Table 2). TABLE 2 Fat content and fatty acid composition of meats * Most wild meats will have similar composition. O'Dea and Sinclair (1983) note that traditional hunterxatherer diets were never rich in saturated fat - even if mainly derived from animals since wild animals are low in fat with a high proportion of polyunsaturated fat. A number of different animal species are quite readily available to even urban dwellers in Australia - these include rabbit, venison and even kangaroo meat. CONCLUSION Abrams concludes from his work (1979) that, based on evidence of the diets of the earliest humans: AustraZopithec<nes, H, erectus and Paleolithic Homo sapiens are omnivorous but that the emphasis of the diet should be on fresh meat or animal protein supplemented with plenty of fresh vegetables, fruits and whole grains along with ample exercise. However, the emphasis in domestic animal production must be on the provision of quality lean meat to consumers. The inclusion of a wide variety of meats is also advantageous provided visible fat and skin is avoided and low fat cooking cooking methods maintained. Lean red meats remain our most readily available source of iron and zinc in easily utilisable forms and thus have an important place in our diets. Visibly lean red meats - particularly beef have a fat content similar to chicken meat which is widely accepted by consumers to be low in fat. The modern western diet should, I believe, include a moderate intake of lean meats along with as wide a variety of other foods as possible so that fruit, vegetables and bread and cereal foods form the basis of the diet. 11 The message to this meeting however is to continue work towards increasing the amount of lean meat available to consumers at the expense of excess fat production7 REFERENCES ABRAMS, H.L. Jr (1979). 3. App Nutrit. 31:43-59 ABRAMS, H.L. Jr (1980). 9. App Nutrit. 32:53-87 AUSTRALIAN BUREAU OF STATISTICS (1985). Catalogue No. 4306.0, Canberra : Australian Bureau of Statistics EATON, S.B. and KONNER, M. (1985). New Eng. J. Med. 312 No 5:285-289 FANTINI, L. and MACDONALD, N.A. (1987). J. Food Tech. In Aust. In print at time of writing. FARB, P. and ARMELAGOS, G. (1980). 'Consuming Passions : The Anthropology of Eating' (Houghton Mifflin Co, Boaston). HARRIS, Marvin (1977). 'Cannibals & Kings, The Origins of Culture'. 1 (Random House, New York). HARRIS, Marvin (1985). 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