Religious restrictions on the consumption of pork are a tradition in the Ancient Near East. Swine were prohibited in ancient Syria and Phoenicia, and the pig and its flesh represented a taboo observed, Strabo noted, at Comana in Pontus. A lost poem of Hermesianax, reported centuries later by the traveller Pausanias, reported an etiological myth of Attis destroyed by a supernatural boar to account for the fact that "in consequence of these events the Galatians who inhabit Pessinous do not touch pork". Concerning Abrahamic religions, clear restrictions exist in Jewish dietary laws (Kashrut) and in Islamic dietary laws (Halal).
Although Christianity is also an Abrahamic religion, most of its adherents are permitted to consume pork – justified by Peter's vision of a sheet with animals and several verses of the New Testament which guides Christians with the Good News of the Gospels. Since Christianity lost most of its roots from Judaism, Christians are not bound to some restrictions of Mosaic Law. However, Seventh-day Adventists consider pork taboo, along with other foods forbidden by Jewish law. The Ethiopian Orthodox Church does not permit pork consumption.
The Torah (Pentateuch) contains passages in Leviticus that lists the animals people are permitted to consume. It first notes what qualifies an animal that is absolutely permitted:
Any animal that has a cloven hoof that is completely split into double hooves, and which brings up its cud that one you may eat.
Animals that have cloven hooves and chew their cud are ruminants such as cows, sheep, and deer. This text does not specify every possible animal by name, only their behaviors.
The text goes on to describe specific animals that are known and meet one, but not both, of those qualifications, thereby prohibiting their consumption. It does not elaborate on the exact reason for prohibition other than physical characteristics.
Pigs are described in this section as prohibited because they have a cloven hoof but don't chew their cud.
And the pig, because it has a cloven hoof that is completely split, but will not regurgitate its cud; it is unclean for you. You shall not eat of their flesh, and you shall not touch their carcasses; they are unclean for you.
Deuteronomy expands on the list of permitted animals.
You shall not eat any abomination.
These are the animals that you may eat: ox, lamb, and kid,
gazelle, deer, and antelope, ibex, chamois, bison, and giraffe.And every animal that has a split hoof and has a hoof cloven into two hoof sections, [and] chews the cud among the animals that you may eat.
Deuteronomy reiterates what Leviticus states on pigs.
And the pig, because it has a split hoof, but does not chew the cud; it is unclean for you. You shall neither eat of their flesh nor touch their carcass.
One example of verses from the Quran on pig consumption:
He has only forbidden to you dead animals, blood, the flesh of swine, and that which has been dedicated to other than God . But whoever is forced [by necessity], neither desiring [it] nor transgressing [its limit], there is no sin upon him. Indeed, God is Forgiving and Merciful.
Scottish pork taboo was Donald Alexander Mackenzie's phrase for discussing an aversion to pork among Scots, particularly Highlanders, which he believed stemmed from an ancient taboo. Several writers who confirm that there was a prejudice against pork, or a superstitious attitude toward pigs, do not see it in terms of a taboo related to an ancient cult. Any prejudice is generally agreed to have disappeared by 1800.
The cultural materialistic anthropologist Marvin Harris thinks that the main reason for prohibiting consumption of pork was ecological-economical. Pigs require water and shady woods with seeds, but those conditions are scarce in the Middle East. Unlike many other forms of livestock, pigs are omnivorous scavengers, eating virtually anything they come across, including carrion and refuse. This was deemed unclean, hence a Middle Eastern society keeping large stocks of pigs would destroy their ecosystem.
It is speculated that chickens supplanted pigs as a more portable and efficient source of protein, leading to the religious restrictions.
Maimonides, the Jewish philosopher and legal codifier, who was also court physician to the Muslim sultan Saladin in the 12th century, understands the dietary laws chiefly as a means of keeping the body healthy. He argued that the meat of the forbidden animals, birds, and fish is unwholesome and indigestible. According to Maimonides, at first glance, this does not apply to pork, which does not appear to be harmful. Yet, Maimonides observes, the pig is a filthy animal and if swine were used for food, marketplaces and even houses would be dirtier than latrines.
The Chinuch Sefer HaChinuch (an early work of Halachah) gives a general overview of the Jewish dietary laws. He writes "And if there are any reasons for the dietary laws which are unknown to us or those knowledgeable in the health field, do not wonder about them, for the true Healer that warns us against them is smarter than us, and smarter than the doctors".