CULTURES TEND to impose supernatural sanctions on the consumption of animal flesh when the cost/benefit ratio of a particular species deteriorates. Cheap and abundant species whose flesh can be eaten without danger to the rest of the food production system seldom become the target of supernatural proscriptions. Animals which have high benefits and low costs at one time, but which become more costly later on, are the principal targets of supernatural sanctions.

The most severe restrictions tend to develop when a nutritionally valuable species not only becomes more expensive but its continued use endangers the existing mode of subsistence. The pig is such a species.

Pig raising incurred costs that posed a threat to the entire subsistence system in the hot, semiarid lands of the ancient Middle East. And this threat increased sharply as a result of intensification, depletion and population growth throughout the region after 4,000 B.C.

The pig is essentially a creature of forests, riverbanks and the edges of swamps. It is physiologically maladapted to high temperatures and direct sunlight because it cannot regulate its body temperature without external sources of moisture - it cannot sweat. In its natural forest habitat the pig eats tubers, roots and fruits and nuts. If it is fed on plants with a high cellulose content, it completely loses its advantage over ruminant species as a converter of plants to meat and fat.

Unlike cattle, sheep, goats, donkeys and horses, hogs cannot metabolize husks, stalks or fibrous leaves; they are, no better than people when it comes to living on grass. Forests Reduced

WHEN THE PIG was first domesticated, there were extensive forests covering the hilly flanks of the Taurus and Zagros mountains and the other upland zones of the Middle East. But beginning in 7,000 B.C., the spread and intensification of mixed farming and herding economies converted millions of acres of Middle Eastern forests to grasslands. At the same time, millions of acres of grasslands were converted to deserts.

Agricultural and pastoral intensification fostered the spread of arid land plants at the expense of formerly lush tropical and semitropical vegetation. Authorities estimate that the forests of Anatolia were reduced from 70 per cent to 13 per cent of total surface area between 5,000 B.C. and the recent past. Only one-fourth of the former Caspian shorefront forest remains, one-half of the mountain humid forest, one-fifth to one-sixth of the oak and juniper forests of the Zagros and one-twentieth of the juniper forests of the Elburg and Khorassan ranges.

Today, as R.D. Whyte has noted, "The bald mountains and foothills of the Mediterranean shorelines, the Anatolian plateau and Iran stand as stark witnesses of millennia of uncontrolled utilization."

The ancient Israelites arrived in Palestine during the early to middle iron age, about 1,200 B.C., and took possession of mountainous terrain which previously had not been cultivated. The woodlands in the Judean and Samaritan hills were rapidly cut down and converted into irrigated terraces. Areas suitable for raising pigs on natural forage were severely restricted. Increasingly, pigs had to be fed grains as supplements, rendering them directly competitive with human beings; moreover, their cost increased because they needed artificial shade and moisture. And yet they continued to be a tempting source of protein and fat.

The ecclesiastical prohibition recorded in Leviticus had the merit of finality: by making even a bit of pig raising unclean, it helped put down the temptation to raise a lot of pigs.

Some of my colleagues have challenged this explanation on the ground that if pig raising was really so harmful there would have been no need for special ecclesiastical sanctions against it. "To require a taboo on an animal which is ecologically destructive is cultural overkill. Why use pigs if they are not useful in a stated context?" But it is the role of pigs in an evolving system of production that is under consideration here. To prohibit raising pigs was to encourage raising grains, tree crops and less costly sources of animal protein.

Moreover, just as individuals are often ambivalent and ambiguous about their own thoughts and emotions, so whole populations are often ambivalent and ambiguous about aspects of the intensification processes in which they are participating. Think of the pros and cons of offshore drilling and the ongoing debate about the taboo on abortions. It was not a matter of "cultural overkill" to invoke divine law against adultery or bank robberies. When Jahweh prohibited homicide and incest, he did not say, "Let there be only a little bit of homicide" or "Let there be only a little bit of incest." Why, then, should he have said, "Thou shalt eat of the swine only in a small amounts"? Why the Taboos?

SOME PEOPLE feel that ecological cost/benefit analysis of pig raising is superfluous because the pig is simply an exceptionally unappetizing creature that eats human excrement and likes to wallow in its own urine and feces. What this approach fails to cope with is that if everyone naturally felt that way the pig would never have been domesticated in the first place, nor would it continue to be eagerly devoured in so many other parts of the world.

Actually, pigs wallow in their own feces and urine only when they are deprived of alternative sources of the external moisture necessary for cooling their hairless and sweatless bodies. Moreover, the pig is scarcely the only domesticated animal that will, given the chance, gobble up human excrement (cattle and chickens, for example, show little restraint in this regard).

The notion that the pig was tabooed because its flesh carried the parasite that causes trichinosis should also be laid to rest. Recent epidemiological studies have shown that pigs raised in hot climates seldom transmit trichinosis. On the other hand, naturally "clean" cattle, sheep and goats are carriers of anthrax, brucellosis and other human diseases that are as dangerous as anything the pig can transmit, if not more so.

Another objection raised against an ecological explanation ofthe Israelite pig taboo is that it fails to take into account the fact that the flesh of many other creatures is prohibited in the Old Testament. While it is true that the pig taboo is but one aspect of a whole system of dietary laws, the inclusion of the other interdicted creatures can also be explained by general cost/benefit principles.

The majority of the forbidden species were wild animals which could only be obtained by hunting. To a people whose subsistence depended primarily on flocks, herds and grain agriculture, the hunting of animals - especially of species which had become scarce of which did not live in the local habitat - was a poor cost/benefit bargain.

The taboo on animals with paws probably included the domesticated cat and dog. Cats were domesticated in Egypt to serve the highly specialized function of rodent control. Eating them, except in emergencies, would not have made life better for anyone except mice and rats. Dogs were used primarily to herd and hunt. To produce meat, anything (other than bones) fed to a dog would be better spent put into the mouth of a cow or a goat.

Another category of forbidden flesh in Leviticus consists of water dwellers without fins or scales. By implication, these include eels, shellfish, whales, porpoises, sturgeons, lampreys and catfish. Most of these species, of course, were unlikely to be encountered in significant numbers on the edge of the Sinai Desert or in the Judean hills.

"Birds" constitute the largest group of specifically identified forbidden creatures: the eagle, ossifrage, osprey, kite, falcon, raven, sea gulls, hawk, owl, cormorant, ibis, water hen, pelican, vulture, stork, heron, hoopoe and bat. All of these are also either highly elusive, rare or nutritionally trivial species.

Turning to the category "insect," it is written that "all winged insects that go upon all fours" are forbidden with the exception of locusts, crickets and grasshoppers, "which leap upon the earth." The exceptions are highly significant. Locusts are large, meaty insects; they occur in vast numbers and are easily gathered for food during what is likely to become a hungry period as a result of the damage they inflict on fields and pastures. They have a high benefit-to-cost ratio.

Although the camel is the only domesticated animal specifically mentioned among the non-cloven-footed cudchewers, rabbinical authorities have always included horses and donkeys in the same category. What these three domesticated species really have in common (none of them "chew the cud") is that they are large high-cost/high-benefit animals kept by the Israelites for their contribution to fit animals kept in significant numbers. The horses was used primarily for aristocratic and military purposes, while camels were specialized for deep desert caravans. Neither could have supplied significant amounts of animal protein without interfering with their primary function. Donkeys were the Israelites' principal pack animal, but these too could not be slaughtered for food except at great economic loss. In other words, the domesticated non-cloven-footed "cudchewers" were just too valuable to be eaten. Increasing Prejudice

THE ANCIENT Israelite pig taboo can never be satisfactorily explained in terms of values and beliefs that were peculiar to the Israelites. The fact is that the Israelites were only one among many Middle Eastern peoples who found the pig increasingly troublesome.

The pig taboo recurs throughout the entire vast zone of Old World pastoral nomadism - from North Africa across the Middle East and Central Asia. But in China, Southeast Asia, Indonesia and Melanesia the pig was and still is a much-used source of dietary proteins and fats, as it is in modern Europe and the Western Hemisphere.

The ancient Israelites shared their abhorrence of the pig with the Egyptians. In the words of H. Epstein, one of the outstanding authorities on the history of animal domestication in Africa, "from a position of extreme importance at the beginning of the neolithic period, [the pig] gradually declined in significance, and records from the dynastic period reveal the development of an increasing prejudice against it."

During Middle Dynastic times (2,000 B.C.) the Egyptians begans to identify pigs with Set, the god of evil. Although pig raising survived into post-dynastic times, the Egyptians never lost their prejudice against pork. Egyptian swineherds were members of a distinct caste. They used their herds to tread seeds into the Nile flood plain as part of the planting process, and this useful function - together with the availability of permanent wetlands and swamps in the Nile Delta - may help to account for the occasional eating of pork in Egypt up to the time of the Islamic conquest. Still, according to Herodotus, the swineherds constituted the most despised caste in Egypt and, unlike all others, were forbidden to enter the temples.

Something similar seems to have happened in Mesopotamia. Archaeologists have found clay models of domesticated pigs in the earliest settlements of Lower Mesopotamia in the fifth and fourth millennia B.C. About 30 per cent of the animal bones excavated from Tell Asmar (2,800-2,700 B.C.) belonged to pigs. Pork was eaten in Ur in pre-dynastic times. In the earliest Sumerian dynasties there were specialist swineherds and pork butchers. After 2,400 B.C., however, pork evidently became taboo and was no longer eaten.

The disappearance of the pig from the Mesopotamian diet coincides with severe ecological depletion and declining productivity in lower Sumeria, the cradle of the earliest Middle Eastern states, which became progressively weakened economically, leading to the collapse of the last Sumerian Empire, the Third Dynasty of Ur. By 1,700 B.C. wheat had completely disappeared in the south. Thereafter, the center of population shifted to the north as Babylon began to emerge under Hammurabi. And even that great "giver of abundant riches" could not afford to keep his people fed on pork.

With the rise of Islam, the ancient Israelite pig taboo was incorporated directly into still another set of supernaturally sanctioned dietary laws. The pig was signaled out for special opprobrium in the Koran, and today Moslems are as opposed as Orthodox Jews are to eating pork. Incidentially, the Koran contains an important bit of evidence in support of the ecological cost/benefit interpretation of animals taboos. The prophet Mohammed retained the Israelite taboo on the pig, but he explicitly released his followers from the taboo on eating camel flesh.

The Arabian pastoralists, Mohammed's earliest supporters, were camel nomads who inhabited true desert oases and who were often obliged to make long journeys across barren wastes where the camel was the only domesticated creature that could survive. While the camel was too valuable to be eaten regularly, it was also too valuable not to be eaten at all. Under emergency conditions associated with military campaigns and long-distance caravan trade, its flesh often meant the difference between life and death.

By tracing the origin of religious ideas to the cost/benefits of ecological process, I do not mean to deny that religious ideas themselves may in turn exert an influence on customs and thoughts. The authors of Leviticus and the Koran were priests and prophets interested in developing a coherent set of religious principles. Once these principles were formulated, they became part of Jewish and Islamic culture down through the ages and undoubtedly influenced the behavior of Jews and Moslems who lived far from their Middle Eastern homelands.

Food taboos and culinary specialties can be perpetuated as boundary markers between ethnic and national minorities and as symbols of group identify independently of any active ecological selection for or against their existence. But I don't think such beliefs and practices would long endure if they resulted in the sharp elevation of subsistence costs. No purely religious urge can run counter to fundamental ecological and economic resistance for a long period of time. I doubt that modern-day observant Jews or Moslems suffer protein deficits as a result of spurning pork. Were this the case, I would expect them to begin to change their beliefs - if not at once, then in a generation or so.

I do not claim that the analysis of ecological costs and benefits can lead to the explanation of every belief and practice of every culture that has ever existed. Many alternative beliefs and alternative courses of action have no clear-cut advantages or disadvantages with respect to raising or lowering standards of living.

Moreover, I admit that there is always some feedback between the conditions that determine ecological and economic costs and benefits and religious beliefs and practices. But I insist that on the evidence of prehistory and history the force they have hitherto exerted on each other has not been equal.

Religions have generally changed to conform to the requirements of reducing costs and maximizing benefits in the struggle to keep living stands from falling; cases in which production systems have changed to conform to the requirements of changed religious systems regardless of cost/benefit considerations either do not exist or are extremely rare.