Pt1 Patterns in Animal and Plant Reproduction According to the Talmud, with Comparison With Modern Biological Scientific Knowledge (Bekhorot 7b-8a)

Reproduction patterns of fish; mammals; bats; dolphins - 4 rules; Correlation between the position of male reproductive organs (external vs. internal) and the birth method of the female

This is the first part of a 3-part series. This part contains Pt1 and Pt2 in the outline that follows:

Outline

1. Pt1 - Reproduction patterns of fish; mammals; bats; dolphins - 4 rules

2. Pt2 - Correlation between the position of male reproductive organs (external vs. internal) and the birth method of the female

3. Pt3 - The relationship between the time of mating and the time of birthing across different species - 3 rules

4. Pt4 - Mating positions - 3 rules

5. Pt5 - The gestation periods of various animals and their parallels in the plant kingdom - List of 11 animals and their corresponding plants

Intro

This sugya makes extensive statements about biological phenomena.

This series will interpret the sugya through the lens of contemporary biological science. Many of the assertions hold true; some principles function effectively as general rules of thumb.

Nonetheless, numerous claims within the sugya do not align with current scientific understanding.

This article aims to methodically review and verify the accuracy of the statements made in the sugya.

The Passage

Bekhorot.7b.20-8a.14

Pt1 - Reproduction patterns of fish; mammals; bats; dolphins - 4 rules

Comparison With Modern Biological Scientific Knowledge

1. Non-kosher fish spawn offspring (דג טמא משריץ), while kosher fish lay eggs (דג טהור מטיל ביצים) - It’s unclear what the meaning is off the statement that “Non-kosher fish are mashritz (משריץ) offspring”, as opposed to kosher fish, which “lay eggs (מטיל ביצים)” . Steinzaltz translates mashritz as “spawn”. But “[a]s a verb, to spawn refers to the process of freely releasing eggs and sperm into a body of water”.¹ It may mean tadpoles.² However, both kosher and non-kosher fish can lay eggs. For example, sturgeon, which is non-kosher, lays eggs.³

2. Any animal that gives birth to its offspring, nurses them (כל המוליד, מניק); and any animal that lays eggs, gathers food [and feeds it to its young] (כל המטיל ביצים, מלקט) - The first part is generally true.⁴ However, Steinzaltz’s bracketed “[and feeds it to its young]” isn’t really true; many reptiles and fish lay eggs and do not actively gather food to feed their young; the young are often left to fend for themselves after hatching. But the passage may mean “gathers” to simply mean that the mother doesn’t nurse the offspring.

3. Bats lay eggs and nurse their young (חוץ מעטלף, שאף על פי שמטיל ביצים, מניק) - This is incorrect. Bats are mammals and do not lay eggs; they give birth to live young and nurse them.⁵

4. Dolphins reproduce like people (הדולפנין פרין ורבין כבני אדם)⁶ -The phrase likely aims to highlight the fact that dolphins, like humans, give birth to live young rather than laying eggs. This is a trait shared among all mammals, including humans and dolphins.⁷

ת"ר: 

1. דג טמא: משריץ, דג טהור: מטיל ביצים 

2. כל המוליד: מניק, וכל המטיל ביצים: מלקט 

3. חוץ מעטלף, שאף על פי שמטיל ביצים, מניק

4. הדולפנין: פרין ורבין כבני אדם 

מאי דולפנין? 

אמר רב יהודה: בני ימא

The Sages taught that 

1. a non-kosher fish spawns its offspring, while a kosher fish lays eggs. 

2. Any animal that gives birth to its offspring nurses them, and any animal that lays eggs gathers food and feeds it to its young. 

3. This applies to all animals except for a bat [atallef ], as although it lays eggs, it nurses its young.

4. The dulfanin reproduce like people. 

The Gemara asks: What are dulfanin? 

Rav Yehuda says: They are creatures that are called sons of the sea.

Pt2 - Correlation between the position of male reproductive organs (external vs. internal) and the birth method of the female (giving birth to live young vs. laying eggs)

Comparison With Modern Biological Scientific Knowledge

The Talmudic passage quotes a beraita and Abaye with statements about male reproductive organs.

The beraita states a correlation between the position of male reproductive organs (external vs. internal) and the reproductive method of the female (giving birth to live young vs. laying eggs).

Abaye states that the male wild goose’s testicles are external, while the domestic goose’s testicles are internal. 

To evaluate these claims based on modern biological knowledge:

1. External testicles imply live birth (כל שביציו מבחוץ, מוליד), internal imply egg-laying (כל שבפנים, מטיל ביצים) - It’s indeed mostly the case that many animals with internal testicles, like most birds and reptiles, lay eggs; while mammals typically have external testicles and give birth to live young.

2. Specific Claim About Geese: The claim that wild geese have external testicles is incorrect. All birds, including both wild and domestic geese, have internal testicles. Birds lay eggs regardless of the external visibility of the testicles, which is consistent across the class.

1. כל שביציו מבחוץ, מוליד;

2. וכל שבפנים, מטיל ביצים

איני? והאמר שמואל: אווז, ואווז בר -- כלאים זה בזה 

והוינן בה: מ"ט? 

אמר אביי: זה ביציו מבחוץ, וזה ביציו מבפנים, ותרוייהו מטילי ביצים

[…]

The baraita continues:

1. In the case of any male animal whose testicles are external, the female gives birth to live offspring,

2. and in the case of any male animal whose testicles are internal, the female lays eggs.

The Gemara asks: Is that so? But doesn’t Shmuel say that a domestic goose and a wild goose are considered diverse kinds, and one may not crossbreed them with each other (כלאים - Kil'ayim). 

And we discussed it: What is the reason? 

Abaye said: In the case of this one, the male wild goose, its testicles are external, and in the case of that one, the domestic goose, its testicles are internal. 

[…]

1. Wikipedia, “Spawn (biology)”.

2. “A tadpole is the larval stage in the biological life cycle of an amphibian“ (Wikipedia, “Tadpole”). This fits with the general meaning of the root sheretz (שרץ), see my discussion in one of the next installments.

3. See Sturgeon - Wikipedia > “Life cycle”.

4. Which give birth and nurse their young, see Mammal - Wikipedia:

“ Mammals are characterized by the presence of milk-producing mammary glands for feeding their young [...]

All modern mammals give birth to live young, except the five species of monotremes, which are egg-laying mammals.”

5. See Bat - Wikipedia > “Reproduction and life cycle”.

6. The Hebrew name (דולפנין) is from from Greek delphín, the source for English dolphin.

7. It’s notable that the meaning of the word dolphin itself is “[fish] with a womb".