What Archaeology Tells Us About the Ancient History of Eating Kosher

A new study of fish remains deepens scholars’ understanding of how the dietary laws came to be

Lod Mosaic
This mosaic featuring fish was likely laid down in A.D. 300 in what is now the Israeli town of Lod. Wikimedia Commons under Creative Commons Public Domain Mark 1.0

In 2017, archaeologist Yonatan Adler and friends paid tribute to a retiring colleague with speeches about how their respective work in the field of archaeology was influenced by each other. After Adler spoke about his research on the mikveh, the Jewish ritual bath, Omri Lernau—senior research fellow at Haifa University and Israel’s top authority on all things fish—spoke about remains of aquatic creatures unearthed in ancient Judean settlements. He mentioned catfish, skate and shark.

Adler, who works at Israel’s Ariel University, was instantly intrigued. According to the Jewish laws of kashrut—the set of rules written in the Torah, the Hebrew Bible, that outline foods suitable for human consumption—these species are deemed non-kosher, and therefore unfit to eat. So why were the ancient Judeans eating them? Did they not yet know these rules? To Adler’s knowledge, no one in archaeology had tried to analyze why remains of the non-kosher fish existed at the ancient Judean settlements. So when Lernau finished his speech, Adler approached Lernau and expressed his interest in the tantalizing relics. The pair agreed to take a deeper dive into where and when the non-kosher fish were being eaten. “I knew it was going to be an interesting subject,” Lernau says.

Now, in a study published today in the journal Tel Aviv, the pair reveals that ancient Judeans, in a period that spans throughout much of the first millennium B.C., enjoyed a diet that didn’t fully adhere to Jewish kosher laws. According to the study, archaeologists have found the remains of three non-kosher species in the two ancients Judean settlements—the Kingdom of Israel in the region’s north and the Kingdom of Judah in the south. Judah residents in particular ate a lot of catfish. These findings help scientists and historians build a more complete picture of how the ancient Judean cultures developed and adopted these rules.

According to rabbinic tradition, Moses, the most important prophet in Judaism, received the commandments that outlined how to live life as a Jew sometime around the 13th century B.C. Scholars don’t know exactly when these rules and practices were written down into the Torah, but in his upcoming book, Adler argues that evidence for its observance does not appear until the Hasmonean period that lasted from 140 B.C. to 37 B.C. And the point in history at which Judean citizens adopted the dietary rules prescribed in Torah into their lifestyles, essentially becoming kosher, is also not certain.

Adler has been working on the Origins of Judaism Archaeological Project, which aims to find out when ancient Judeans began to observe the laws of Torah, including dietary rules. He was hoping that the centuries-old fish scraps tossed away after dinner might help shed some light on that. “I can find out a lot about people by going through their garbage,” he says. “So we can learn a tremendous amount of what people were actually doing through the material remains they left behind—and this is particularly true for food.”

When both kingdoms rose to prominence, an average Judean denizen lived under the rule of a king, and was a farmer who plowed fields and harvested crops. With the exception of the societal elite, most individuals were illiterate. So while the educated intellectuals of the time had penned down laws, scribbling them on animal skins or papyrus, the vast majority of Judeans didn't necessarily know about them and couldn’t read them either. Even if the societal intellectuals may have started adopting kashrut, the masses likely hadn’t yet gotten the memo.

“I am interested in social history, in what, the actual regular people were doing but they didn't leave any texts because they were illiterate and left no writing,” Adler says. Archaeology can help bridge that gap, he notes. “If we want to know what the regular people were doing or not doing, archaeology is a wonderful tool to answer this question.”

The two scientists didn’t have to dig deep for the vestiges of aquatic life— Lernau had a collection of about 100,000 fish remains gathered from dozens of sites in Israel, which spans 10,000 years, from the Neolithic times to the present. Originally started by his father, it has every piece tucked away in an envelope and filed in meticulously labeled boxes. The collection resides inside his home’s Fish Bone Cellar, which doubles as a bomb shelter during times of armed conflict. Lernau spent three years combing through the boxes and identifying fish species eaten at the ancient Judean settlements ages ago. Altogether, he had looked at about 20,000 fish scraps. It’s important not to call them bones, he notes—because while catfish have bones, the skeletons of sharks and skates are composed of cartilage, the softer connective tissues that in humans makes up joints. These creatures don't leave behind bones, but rather calcified fragments of their cartilaginous vertebrae and an occasional tooth.

Shark Centrum
The body of a shark vertebrate excavated from a site in Ashkelon, in Israel Omri Lernau

The two collaborators found that during the Persian Period, which lasted from 539 to 332 B.C., centuries after it is believed Moses received his commandments, ancient Judeans ate a lot of catfish as well as skate and shark, two other non-kosher species. (The reasons for their taboo nature are incredibly complex but have to do with their lack of the proper type of scales.) Fast-forward to the Roman times that span from 63 B.C. to 324 A.D., and the scaleless fish remains nearly disappear from the ancient trash. Unfortunately, very little fish data falls in between the two timeframes examined, in the Hellenistic Period. That doesn’t necessarily mean individuals weren’t eating fish; it may just mean that archaeologists haven’t unearthed enough fish bones from the Hellenistic household rubbish. Typically small, the fish scraps are harder to find in dusty digs, so archaeologists must sift through the dirt to spot them. That’s a laborious and time-consuming process, so scientists will only do that if they expect to find something of value—and fish fragments aren’t a prized item for many researchers.

Lidar Sapir-Hen, archaeozoologist at Tel Aviv University, who also studied the history of Judeans’ dietary restrictions but was not involved in this study, found similar evidence that Judeans weren’t following the laws of kashrut around similar dates that Adler examined. She had examined pig bones found in ancient Judean settlements. Pork is another type of non-kosher food and yet some digs yielded a number of pig remains. The ancient Kingdom of Judah, located in the region’s south part had very few pig bones, but the Kingdom of Israel up north had quite a few.

“It looks like in the Kingdom of Israel, a lot of people ate pork during the 8th century B.C.,” Sapir-Hen says. “So we think that these dietary prohibitions happened later.” Thus, the new study adds to the already mounting evidence that ancient Judeans weren’t strictly kosher. “I was happy to see that Yonatan and Omri came to a very similar conclusion as we did,” Sapir-Hen says.

Lernau and Adler hope that their paper will not only add to the existing knowledge about ancient Judeans, but also will inspire more archeologists to search for fish bones in the primordial dust. “Hopefully, more people will be looking for them now,” Lernau said.

Adler also hopes that the study will encourage scholars of different disciples to join forces in studying history. Scientists often work in silos, he points out. The text scholars bury their noses in books while archaeologists shovel dirt in their digs. He says the two camps could unearth a lot of history together by comparing notes and evidence. “We need to look at whatever scanty remains of the past we have,” he says, “and make the best use of them we can.”

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