Science and the Talmud

The Talmudic approach to the sciences, from astronomy to botany.

Print this page Print this page


The vast lists of plants, trees, and flowers mentioned in the Talmud read almost like a botanical guide to ancient Babylonia. The rabbis categorized the flora around them, often to illuminate both legal and non-legal biblical passages but sometimes seemingly for its own sake.

Fruits that came from trees, as opposed to those that came from the ground, received different blessings. The Talmud reports their extensive investigation to determine what plants grow where. Some major mitzvot required knowledge of botany, such as the commandment to shake a lulav--a bouquet of palm, willow, and myrtle--and to cover a sukkah with agricultural material. What was allowed to cover a sukkah? From where exactly was one to take the palm branch for the lulav?

On  Shavuot, Jews were to bring the firsts of their produce to Jerusalem. But what counted as first fruits? Maror, bitter herbs, were to be eaten on Passover. What kinds of lettuces fulfilled the obligation of maror? All of these required botanical investigations.

Biology & Genetics

The rabbis believed that certain activities conducted by parents could affect the child prior to conception and in utero. In Nedarim 20a-b, the rabbis suggest that the nature of copulation could affect the health of the infant. Once conceived, they believed other behaviors such as smelling an etrog or working in a tannery could  positively or adversely affect the child (Ketubot 60b-61a).

The Talmud also considers the question of whether prayer can help to determine the gender of an unborn baby. The rabbis reject this possibility in Berakhot 60a:

Has not Rabbi Isaac the son of Rabbi Ammi said, If the man first emits seed, the child will be a girl; if the woman first emits seed, the child will be a boy?

Although their understanding of genetics and biology was incorrect, their refusal to link prayer to sex determination implies a positioning of the physical world as distinct from the spiritual in this matter.

Zoology/Animal Behavior

In addition to human traits, animal behavior was also a concern of the talmudic rabbis. For example, the end of Shabbat was determined by the appearance of three stars. The rabbis ask, "What happens if the skies are cloudy and one cannot see any stars?" One is directed to watch the fowls descend from their perches or the ravens fly from the fields (Shabbat 35b). When they do, night had arrived and Shabbat was over.

The Talmud also reports rabbis trying to explain animals and their behavior as mysteries of the world, independent of their contribution to halakhah:

Rabbi Zera met Rav Judah standing by the door of his father-in-law's house and saw that he was in a cheerful mood, and if he would ask him all the secrets of the universe he would disclose them to him. He asked him: Why do goats march at the head of the flock, and then sheep after them? He said (quoting a scriptural verse): It is as the world's creation, darkness first and then light…. Rabbi Zera asked: Why is a camel's tail short? Because it eats thorns and a long tail would get stuck in the thorns. Why is an ox's tail long? Because it grazes in meadows and has to beat off the gnats with its tail…. (Shabbat 77b)

What is striking about this passage is that at first the Torah is invoked in order to explain animal behavior, but then the explanations about the other animals seamlessly move to that which is observable in the world independent of any commandment. The world is not only explainable through the Torah, but also through observation, hypothesis, and confirmation.

All in all, it is difficult to suggest one attitude towards science in the Talmud. Its vastness contains what seem to be attitudinal contradictions. There are times that the rabbis encounter scientific theories that compete with their own understanding, forcing them to discard theories and revise their worldview. But, there are other instances where they decide that their understanding is right because it is based on something that is revealed to them.

Since Jewish law is not based on the Talmud alone, when contemporary science and the scientific understanding in the Talmud conflict, one cannot assume that Jewish law should be revised. Other considerations may compel the law to stay the same, despite the "errors" upon which it seems to be based. Because there is an understanding that science, by its nature, is always provisional, more authority is given to the process of deciding Jewish law, than the facts themselves, scientific or otherwise, upon which decisions are made.

Did you like this article?  MyJewishLearning is a not-for-profit organization.

Please consider making a donation today.

Rabbi Micah Kelber

Micah Kelber received his rabbinical ordination from the Jewish Theological Seminary in 2004 and his Masters of Education from The William Davidson School at JTS in 2005. He served for three years as the rabbi at the Bay Ridge Jewish Center and is now building his freelance writing and freelance rabbi practice in Park Slope, Brooklyn.