What size were ancient eggs eaten on Passover?

After surveying some of the oldest eggs ever found in archaeological digs, Bar-Ilan University (BIU) Prof. Zohar Amar discovered they were significantly smaller than previously thought. As the Jewish holiday of Passover approaches, new questions about eggs – an important component in the festive Seder meal and as a measurement for matza – have been answered.

When in history were the first eggs eaten and what size were they? The answers have emerged from a new study published in the scientific Jewish Studies Internet Journal (JSIJ) under the title “Egg measurement in the light of ancient reality” and conducted by Prof. Zohar Amar, an expert in ancient flora and fauna from BIU’s Martin department of Land of Israel studies and archaeology. It gave the full story following a preliminary study by Amar in 2019.

Due to their delicacy and fragility, eggs are generally difficult to preserve and thus a rare archaeological find. In his in-depth study, Amar surveyed 15 of the most ancient, well-preserved eggs ever found in and outside

Israel. The earliest evidence examined are large eggshells from the First Temple period uncovered during excavations of the City of David. Eggs dating to the Roman period and the Middle Ages were also studied. These eggs, completely intact, were well-preserved because they were found in septic tanks and sewage.

According to the findings of the study, chicken eggs became a significant part of the food basket only during the Hellenistic-Roman period, and their size was smaller than thought until now. Further, Amar’s analysis of historical sources revealed that the average egg volume in all periods was 40 to 44 cubic centimeters less than that accepted in Jewish law (Halacha). This new data may carry important halachic implications, as various halachic rulings are determined according to the size of an egg, for example the directive to eat matza kebeitza – “the size of an olive” – during the Passover Seder. According to different halachic opinions, this is calculated as between a quarter to half an egg.

THE EGGS ARE SMALLER than what is accepted nowadays according to the calculation of 57 cc made by the late halachic scholar Rabbi Avraham Chaim Naeh,” explained Amar. “The late leader of ultra-Orthodox Judaism in Israel Rabbi Avraham Yeshaya Karelitz, also known as the Chazon Ish, thought that modern-day eggs were smaller and were twice the size in the past with a volume of about 100 cc.”

In fact, eggs’ relatively small volume existed until the middle of the 20th century. Their size and volume increased only in recent generations, following the cultivation of hen breeding.

Kebitza is one of the most important Torah lessons, according to which the size of the minimal etrog (citron) that is kosher for using on Succot is determined. As with the lesson on impurity of food, the main and important use of this lesson is to learn the basics on which the other volumes are calculated. The meaning of an egg in this measure is the hen’s egg, Amar wrote. “Therefore, it seems that they began to hypothesize the useful volume measurements based on eggs in everyday life only when they became a relatively common product in the Roman 5th period, and echoes of this appear in the Talmud. Many Torah studies and discussions have discussed the issue of the egg rate and were based on various calculations and partial information,” he declared.

The egg size was not fixed like nowadays, and it may have changed according to different parameters. Although it referred to an average size, this average may vary from place to place, Amar wrote. “As we know, nowadays different calculation methods are accepted for the egg-in-shell rate. They changed significantly over the generations until the middle of the 20th century. Only since then has there been a certain change in their volume due to the cultivation of breeds of chickens for eggs. It is accepted that the rooster in the ancient Land of Israel was domesticated from several species of wild roosters, including the Bankiba rooster. This rooster probably spread from the Indian region to Mesopotamia, and from there to the Land of Israel at the end of the second millennium BCE.”