This Bible History Daily feature was originally published in July 2012. It has been updated.—Ed.
The origins of Jewish dietary or kosher laws (kashrut) have long been the subject of scholarly research and debate. Regardless of their origins, however, these age-old laws continue to have a significant impact on the way many observant Jews go about their daily lives. One of the more well-known restrictions is the injunction against mixing meat with dairy products. Not only do most Jews who observe kashrut avoid eating any meat and milk products together, many also wait a certain amount of time—30 minutes to a few hours—between eating meat and dairy. Everything the foods touch must be kept completely separate. A fully kosher household, for example, might have two or more different sets of flatware, tableware and cooking ware for making and serving meat dishes separate from dairy-based dishes. Some families even use two different dishwashers in order to maintain the separation. Outside the house, some Jews keep kosher by eating only at kosher restaurants while others have no problem eating non-kosher foods, so long as they maintain a kosher home.
But what are some of the other laws of kashrut, and how are they to be explained? Many of the dietary restrictions outlined in Deuteronomy and Leviticus prohibit the consumption of certain “unclean” animals that either don’t chew their cud or don’t have cloven hooves, such as pigs, camels and rabbits. Likewise, while the Hebrew Bible permits the eating of fish with fins and scales, shellfish like lobsters and crabs are an abomination. Why were such seemingly innocuous physiological traits so objectionable to the early Israelites?
The free eBook Life in the Ancient World guides you through craft centers in ancient Jerusalem, family structure across Israel and articles on ancient practices—from dining to makeup—across the Mediterranean world.
One possible reason may be that the Israelites wanted some way to distinguish themselves from their non-Hebrew neighbors. Archaeological excavations of Iron Age I sites in Israel have shown that while pigs were a popular part of the Philistine diet, they were entirely absent from the herd-based economy of the Israelites. According to Ronald Hendel, such culinary distinctions soon became codified markers of cultural identity, whereby “the Philistine treat became an Israelite taboo.”*  Perhaps similar efforts to affirm Israel’s uniqueness lay at the heart of other animal prohibitions.
But according to kashrut, even permissible animals have to be prepared in a certain way in order to remain kosher. As explained in Deuteronomy 12:23-24, for example, the blood of a slaughtered animal cannot be ingested, for “the blood is the life, and you shall not eat the life with the flesh.” The Israelites, like many ancient peoples, believed that an animal’s blood carried the soul of the animal and therefore should not be consumed.**  Thus, before a piece of meat could be cooked, it had to be fully drained of its blood. Though not discussed in the Bible, traditional kosher methods for doing this include broiling the meat or a combination of soaking and salting.
The Last Supper is history’s most famous meal. Was it a ritual meal held in celebration of the Jewish holiday of Passover? Read Was Jesus’ Last Supper a Seder? by Jonathan Klawans online for free as it appeared in Bible Review. 
Kosher law also forbids the consumption of wine that has been made, bottled or handled by non-Jews. Although this prohibition does not appear in the Hebrew Bible, it seems to have been followed as early as the second century A.D. In antiquity, wine was often used in libation rituals to various deities; for Jews this meant that any “pagan” wine could potentially have been made or used as a sacrifice to a foreign god. Thus, in order to avoid coming into contact with contaminated wine, Jews began making and bottling their own wine in accordance with Jewish law.
Learn about farming and dining practices in the Biblical world in the BAS Library Special Collection Feeding the Biblical World . Not a BAS Library member yet? Join today. 
Learn more about farming and dining in the Biblical world in the BAS Library:
Gershon Edelstein and Shimon Gibson, “Ancient Jerusalem’s Rural Food Basket,”  BAR, July/August 1982.
Mordechai E. Kislev and Ehud Weiss, “Weeds & Seeds,”  BAR, November/December 2004.
Thomas E. Levy, “How Ancient Man First Utilized the Rivers in the Desert,”  BAR, November/December 1990.
Dennis E. Smith, “Dinner with Jesus & Paul,”  Bible Review, August 2004.
Gloria London, “Why Milk and Meat Don’t Mix,”  BAR, November/December 2008.
Jack M. Sasson, “Should Cheeseburgers Be Kosher?”  Bible Review, December 2003.
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*Ronald S. Hendel, “Of Sacred Leopards and Abominable Pigs,”  Bible Review, October 2000.
**Bryan Bibb, “What’s a Pleasing Sacrifice?”  Bible Review, October 2004.