Throughout history, the pig has been an animal with a deeply fraught significance for Christians and Jews as well as Muslims. Why, for example, are Jews forbidden to eat pig meat at the same time Christians happily serve up ham for Easter?

The answer may involve more than simply the biblical prohibition against Jews eating pork. If you understand the pig’s symbolism, you can understand the complex and often tortured relationship between Jews and Christians, says French cultural anthropologist Claudine Fabre-Vassas.

In her book “The Singular Beast: Jews, Christians and the Pig” (Columbia University Press, 1997), Fabre-Vassas depicts the pig not only as a beloved figure in medieval and modern Christian households, prized as both a pet in peasant cultures and a source of delicious food, but also as a symbol of a hated figure, the Jew, of the very group that scorns it as unclean. Fabre-Vassas argues that the cultural tension between those who did and those who did not eat pork helps set the stage for a murderous anti-Semitism.

The Jewish interdiction against the pig is first mentioned in the Old Testament. In Leviticus 11:27, God forbids Moses and his followers to eat swine “because it parts the hoof but does not chew the cud.” Furthermore, the prohibition goes, “Of their flesh you shall not eat, and their carcasses you shall not touch; they are unclean to you.” That message is later reinforced in Deuteronomy. Muslims, who follow Mosaic law, inherited the prohibition.

Over the years, various explanations have been offered for the Old Testament commandment. The 12th-century rabbi, Moses Maimonides, court physician to the Muslim sultan and warrior Saladin, said the prohibition against eating pig meat was for health reasons as it had a “bad and damaging effect” upon the body.

Beginning in the 19th century, scholars offered a different explanation. In “The Golden Bough,” Sir James Frazer wrote that pig meat was forbidden because it had originally been an animal used for sacrifice. “All so-called unclean animals were originally sacred,” Sir James wrote. “The reason for not eating them is that many were originally divine.”

British anthropologist Mary Douglas, in her 1966 book “Purity and Danger: An Analysis of Concepts of Pollution and Taboo,” explains the prohibition as a problem of taxonomy: The pig did not fit conveniently into the Israelites’ definitions of what a domestic animal should be (the cloven hooves, the failure to chew their cuds like cows). Animals like pigs that cross over definitions, Douglas argues, that crawl instead of walk or swarm instead of fly, defied the tribal need to create an intellectual ordering of the world. Disorder of any kind, Douglas writes, provided a frightening glimpse into the chaos inherent in the universe.

Later, another anthropologist, Marvin Harris, gave a decidedly utilitarian explanation for the taboo against pork, arguing in his 1974 book “Cows, Pigs, Wars and Witches: The Riddles of Culture” that the prohibition was a response to the realities of nomadic life in the arid stretches of Palestine.

Harris points out that the pig does indeed wallow in its own filth and eats its own feces, but usually only under conditions of severe drought. Cows and sheep will also eat their own feces under extremely dry conditions, he adds.

But pigs require larger amounts of moisture than cows or sheep, he says, and are therefore difficult to raise in hot, dry climates: It was easier, in the end, to forbid people to eat something that they might long for. “Better then, to interdict the consumption of pork entirely,” Harris writes, “and to concentrate on raising goats, sheep and cattle. Pigs tasted good, but it was too expensive to feed them and keep them cool.”

Whatever the reason, the prohibition against eating pig meat became an identifying feature, a defining characteristic of Jewishness. And that, says Alan Dundes, professor of anthropology and folklore at the University of California, Berkeley, is precisely the reason that Christians not only eat pork, but even celebrate it by eating it on holidays. “You distinguish yourself by not doing what others do,” Dundes writes.

It was in the early Christian period, in the first century, that the great divide opened up between those who ate pork and those who didn’t. Early Christians, then simply a sect among the Jews, were faced with the problem of distinguishing themselves. They did not circumcise their children. And they ate pork, the very animal that their fellow Jews avoided. What’s more, where Jews, under biblical command, drained the blood of meat before they ate it, Christians symbolically drank the blood of Christ, and ate His body through the sacrament of the Eucharist.

“There is virtually no religion that we know of that doesn’t define itself with food,” said Gillian Feeley-Harnik, a professor of anthropology at Johns Hopkins University and the author of “The Lord’s Table: The Meaning of Food in Early Judaism and Christianity” (Smithsonian Institution Press, 1994).