Looking at the Gemoro, people used to believe that babies born at 7 months were more likely to survive at 7 months than 8 months. A male is born face down whereas a female is born face up. Another source describes 2 channels in the male sex organ; one for urine and one for semen? How did these beliefs arise and how could people have believed things like this if they are demonstrably false? There are also various tereifos that were fatal, but no longer. Was it really the case that no one bothered to check?Alternatively, has nature changed? I believe these ideas are myths which is why I've posted them here. Rambam speaks about astronomy. In those days they couldn't prove things one way or another. The examples above would have been testable in those days as they are today. Is it possible to test if the Talmud's description of human anatomy was correct eg finding a skeleton over 1800 years old. Another example is the idea that people have 248 bones and 365 tendons or muscles. Nowadays we know an adult has 206 bones. Perhaps they looked at a child's body or perhaps they followed an accepted tradition which had never been checked. In summary: Can the scientific beliefs in the Talmud be tested? If reality was the same as today, why did no one point out the errors?

  • Highly related answer: judaism.stackexchange.com/a/38021/15256 Commented Dec 28, 2019 at 19:40
  • I think the gemarra assumes a baby that is born after 8 months would definitely be a stillborn, which would have been easily verifiable.
    – robev
    Commented Dec 28, 2019 at 23:18
  • Also, is this on topic? Sounds like a science question
    – robev
    Commented Dec 28, 2019 at 23:22
  • Mmmm, if nature changed in general and the nature of people in particular, one should ask; why has nature changed? Or, what benefit could be derived from a change in nature?
    – Jonathan
    Commented Dec 29, 2019 at 2:19
  • Also, see Moreh Nevuchim 3:14 where Maimonides writes that "science of those days was deficient... and they did not speak out of traditions from the prophets regarding these matters."
    – Jonathan
    Commented Dec 29, 2019 at 2:49

3 Answers 3


When examining Maimonides' medical writings and comparing them to the medical advice of the Talmud, one is often left in shock. Many, if not all of the ideas contained in the Talmud are erroneous when in comparison to the findings of modern science. How can such pious talmudic rabbis err? Is it possible that such holy men could make mistakes? Maimonides explained that the ancient rabbis were not experts in science and often had to work with the science of their day, and since the science was frequently wrong, it is no surprise that they were also in error.[1]

Thus, the ancient rabbis had limitations and did not always understand science fully. As a result, they are frequently wrong because they relied on the primitive science of their age. But since science progresses, it is no surprise that Maimonides even admits that future generations will understand science better than he does.[2]

Did people’s nature change? No. Natural law is fixed and needs no change. G-d created the world perfect, as the Bible says "Very good."

[1] (Guide to the Perplexed, III:14) 

[2] See Guide 2:24

  • The Gemoro quotes a rabbi telling someone that a snake is pregnant for 7 years. The person tests this and confirms the rabbi is correct. Which snake could this have been or is the translation of arod as snake incorrect?
    – AlHal
    Commented Dec 29, 2019 at 7:38
  • This may be of interest
    – AlHal
    Commented Dec 29, 2019 at 9:38
  • 1
    Thank you for sharing the link. I did not know that Leonardo Da Vinci was the first to study the human body anatomy in this way. Regarding the snake, it is possible that the rabbis observed the pregnancy of snakes. I do not know the specific Gemoro. Whether or or not this is correct does not matter since the ancient rabbis, though wise in Torah, were limited to the science of the Greeks and Babylonia, which was wrong in many ways.
    – Jonathan
    Commented Dec 29, 2019 at 17:14
  • Bechorot 8 appears to use the scientific method of experimentation to prove results. Furthermore the testing is done by gentiles. If the gentiles actually checked the length of the snake's pregnancy, does that not show that nature has changed?
    – AlHal
    Commented Dec 31, 2019 at 7:32
  • @AlHal When Greek scientists found that snakes were pregnant for 3 years, Rabbi Joshua replied that Jews were smarter (Bechorot 8a). The book “Judaism’s Encounter with Other Cultures” and Rabbi Michael Leo Samuel’s book “Gentle Judaic Wisdom” show many good examples of Jews listening to non-Jews. Thus, Maimonides rejected this notion called the decline of the generations and Jewish superiority (see introduction to his commentary on Mishnah and Guide 3:14).
    – Jonathan
    Commented Dec 31, 2019 at 21:27

With these types of questions, one needs to be very careful about how he understands the words of the Sages. Often the contradiction comes from a mistaken or simplistic understanding of their words, and a deeper understanding shows that there is no contradiction.

For example, the first part of the question, about the seven month and eight month babies. Chazal say that a seven month baby can live, and an eight month baby cannot, unless the eight month baby is really a seven month baby who was born late. This is true; there are seven month babies who are perfectly healthy (one was born to a friend of mine), and an eight month pre-term baby cannot survive without medical intervention. Is a baby born at eight months more likely to be pre-term? Halacha seems to say yes. Compared to a seven month baby? Is that an easy comparison to make?

Skipping to the case of trefos, Chazal give us a list of trefos, and there is a dispute if an animal with such an injury will necessarily die. We see that, for some of these injuries, the animals live. That could mean that the reality is like the one side of the dispute, or it could mean that these injuries are not always fatal, and just that such an injury could cause death. The other side of the dispute could hold that some trefa injuries are not fatal at all. Or it could mean that we don't know the proper definition of those injuries that Chazal listed.

  • I don't understand what you are saying about the babies. There are more eight month babies who don't need intervention than seven month babies.
    – Double AA
    Commented Jan 19, 2020 at 23:06

With regard to things discussed in the Gemorah, they were frequently very easily observable and determinable even in ancient times. They couldn't have simply gotten those things wrong.

(The answer which is usually given about the Gemorah which mentions people having 248 bones is not that nature changes. That Gemorah also explicitly says they dissected corpses and came back to ask their Rebbe that they didn't find 248 bones)

Even without the Gemorah, based on non-Jewish medical history books I see no question that things have changed since ancient times. It's simply inconceivable that in ancient times they practiced all those wacky medical techniques (not mentioned in the Gemorah)if they helped no one. They had to have helped back then. If they were really so ineffective people would have noticed. They never could have caught on and been practiced to such a large extent if people didn't see any improvement that they could clearly attribute to having those medical techniques done.

  • Are there any alleged changes in nature that can be tested eg finding a 1500 year old preserved body?
    – AlHal
    Commented Jan 20, 2020 at 20:23
  • Can you give an example of a Gemorah explained by the changes in nature that would be apparent in a 1500-year-old preserved body?
    – Schmerel
    Commented Jan 21, 2020 at 2:09
  • I'm looking at Rabbi Avraham's encyclopedia of medical ethics p. 144. The Gemoro says that there are two channels in the male sex organ, one for the flow of urine and one for the flow of semen. The distance between them is only the thickness of garlic peel (Bechorot 44b). Some rabbis say that nature has changed and today the membrum has only a single channel and the semen enters the membrum at is base next to the body. Others disagree and say the Gemoro refers to the internal origin of urine and semen channels prior to their entrance into the membrum. Therefore, nature has not changed.
    – AlHal
    Commented Jan 21, 2020 at 21:01
  • The Gemoro describes an extra lobe in the right lung found only in wild animals which is called the little rose lobe (Chullin 47a). However, nowadays we find this lobe in all animals. Therefore, a change in nature occurred from what it was in previous generations.
    – AlHal
    Commented Jan 21, 2020 at 21:03
  • Assuming you are correct in your understanding of the Gemorah that is yet another proof that nature has changed. There is simply no way that all animals had an extra lobe but even so Rav Ashi with all the lungs he checked never came across it and Rav Huna quoting the butchers said it is only found in wild animals if it weren't the case at that point in time. Were the butchers all so blind to not have noticed it non-wild animals?
    – Schmerel
    Commented Jan 21, 2020 at 22:26

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