Thursday, December 13, 2018

The Making of Twins

A constant claim issued by non-rationalists, such as Rav Aharon Feldman and Rabbi Moshe Meiselman, is that it's absurd to state that Chazal or the Rishonim could have been mistaken about scientific facts, because their knowledge was far ahead of their era; Chazal knew things that have only recently been discovered by modern science. Over the last twenty years I've examined many such claims, and in every single case, I discovered that the alleged modern scientific facts stated by Chazal are either

1) things that do not mean what they are claimed to mean, or are so ambiguous that they can be interpreted in all kinds of ways;

2) things that non-Jews knew also; or

3) things that are not actually true.

I recently came across a new such claim, proposed by our old friend "Rabbi" Yosef Mizrachi. He argues that until twenty years ago, nobody knew how identical twins are formed. They knew that non-identical twins are formed by two sperm combining with two eggs, but they did not know how identical twins are formed. Chazal, on other hand, did know: "The Gemara said, one seed went into one egg and split into two!" Mizrachi goes on to stress how eggs cannot be seen without a microscope, implying that Chazal could only have known this due to supernatural knowledge. (He then segues into mocking evolution, and asks why anyone would go to college and pay to be taught nonsense; he finishes by telling his audience that they don't know how lucky they are to be able to be listening to him.)

Is his claim true? Of course not. Let's leave aside the minor inaccuracy regarding when medical science discovered how identical twins are formed (it was not twenty years ago - it was already known in the nineteenth century). And let's leave aside the inaccurate claim that a human egg is too small to be seen without a microscope - it isn't. Let's just address his claim that the Gemara said that "one seed went into one egg and split into two."

There ain't no such Gemara.

What the Gemara (in Yevamos 98b and Niddah 27a) actually says is that twins are formed "when one drop (tipah) divides into two." The word "drop" refers to the male sperm, not to the female ovum. Similarly, Aristotle believed that twins result from an abundance of sperm; it is the intuitive, albeit incorrect, conclusion. Chazal did not know that females produce ova. Rather, they had a different idea as to the role that a woman plays in the formation of a fetus:
"Our Rabbis taught: There are three partners in the creation of man - God, the father and the mother. The father seminates (mazria) the white substance, from which are derived the bones, vessels, fingernails, brain and the white of the eye. The mother seminates (mezara'at) the red substance, from which are derived the skin, flesh, hair and the black of the eye. God provides the spirit, the soul, the beauty of the features, vision for the eyes, hearing for the ears, speech for the mouth... and intelligence." (Niddah 31a)
Ramban elaborates that the fetus is not formed from any female "seed," as there is no such thing; rather, the "red substance" to which the Sages are referring is uterine blood. Tashbetz writes similarly.

So, rather than Chazal knowing how twins are formed long before modern science discovered it, Chazal actually had a mistaken view of fetal development (as did everyone in antiquity). It is, of course, very psychologically reassuring to believe that Chazal knew modern science through supernatural means. Alas, there is no evidence for it, and overwhelming evidence against it.


For further discussion, see:
Jeremy Brown, On Twins, and the Sperm that Splits in Two
Edward Reichman, The Rabbinic Conception of Conception: An Exercise in Fertility

33 comments:

  1. Is there a tradition of rabbis claiming a superior knowledge of science? I believe there is and your fight is with a much larger and more ancient group of rabbis than rabbis meiselman and feldman.

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    1. The key word here is "believe." Your belief, unsupported by proof of any kind, motivates no response

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  2. Please explain. Didn't they dissect bodies? What did they think the function of the ovaries were? Why did only women have them?

    When I dissected grass-hoppers in science class we knew what the eggs were.

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  3. Even if the Gemorah is referring to identical twins, there would still be a big problem.
    The context of both of these Gemorahs is that the only way for twins to develop is from one drop splitting into two and therefore twins must come from one father.
    This has serious Halachik ramifications, as can be seen in those Gemorahs.
    However, if we say the Gemorah was only referring to identical twins, then presumably non-identical twins can come from two fathers, as they are from two drops.
    Hence, the entire basis for the Halachah of the Gemorah falls away!

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    1. of course as far as we know, biologically speaking, non identical twins can in fact come from 2 different fathers.

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    2. You ask a very good question!
      Can someone please attempt an answer?

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  4. Mizrachi says seeds cannot be seen with a microscope.
    You counter that ova can be seen with a microscope.

    Dave

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    1. If you listen to the video, he says both.

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    2. not only both can be seen but in in-vitro fecundation the spermatozoa can be introduced in the ova with a micro-pipette.

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  5. As soon as I read this "The Gemara said, one seed went into one egg and split into two!", I knew that he never read the Gemara! I did a little research while reading a book about birth control and halacha. HaZaL, especially the Zohar believed in Preformism, or that the sperm was a completely formed human, and needed to be planted inside the uterus. This is probably why the Zohar feels that masturbation is a sin worse than murder, as it is the murder of millions of tiny humans.

    Clearly knowing that is the way HaZaL viewed it, you know that Miz is making things up.

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  6. The motivation to attempt to quantify chazal, rest assured stems not from a place of truth or humility....

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  7. You wrote "Rabbi" Mizrachi in quotes.Is he not really a Rabbi? I am not arguing;i honestly do not know. Thanks.

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    1. I have investigated him and have not found a single Yeshivah of note where he has attended and he certainly has not received any form of smichah. In fact his whole background, supposed yeshivah he runs in IL, army service, wall st. success etc. are all shrouded in mystery. Really he is a skilful manipulator with a gift for words and social media. His completely negative approach to kiruv - based on the 'stick', fear and violent castigation of the other - taps into current populist trends.

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    2. He is a Rabbi. The quotation marks are because it is unfortunate that he is one.

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    3. I don't think he received semicha. Now that doesn't mean he can't be called "rabbi" - the term rabbi just means someone who teaches Torah. But I don't know if he does that either. The lectures of his that I have heard are just rambling mussar tirades without any Torah content.

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  8. The father seminates (mazria) the white substance, from which are derived the bones, vessels, fingernails, brain and the white of the eye. The mother seminates (mezara'at) the red substance, from which are derived the skin, flesh, hair and the black of the eye

    There about a million inaccuracies in this statement alone

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  9. I can't quite articulate this fully but I don't think Chazal are referring to the physical body in the way that you take it.
    There is an interesting piece in the Ramchal where he describes that the information about the child is passed over to the mother in the "tzurah of the seed". Aryeh Kaplan translates 'tzurah' as 'DNA', in other words reinterprets the statement in physical terms. But I don't think that's what it means. 'Tzurah' is tzurah. As in the Greek 'forms'. This would imply some kind of background information that would determine how the phsyical DNA and cells would unfold to create the child. I think this is more what Chazal are referring to, and not that the physical bones come from the father and the physical flesh comes from the mother.

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    1. This is unlikely. We say these kinds of things in hindsight with modern knowledge that they didn't have. People say the same thing about the four elements, the four humours, etc.

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    2. The Sfas Emes says repeatedly that the four elements have their roots in the Name of Hashem. remember the hishtalshelus olamus of the Ari's kabbala and at a certain point it seems you lose sight of Hashem and His name manifests in a covered way.

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  10. This comment has been removed by the author.

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  11. Natan, you might write a post pointing out the following. . .

    The Mesechet Shabbat talks about a 7th month baby, 8th month baby, and a 9th month baby. It notes that the 7th and 9th are viable, and the 8th is not. Obviously, this is now scientifically not true.

    The Hazon Ish resolved this, by stating that nature has changed, which is the classic anti-rationalist perspective.

    I discovered that this 7th,8th,9th month meme comes straight from Hippocrates, and was widely held in the ancient world. I learned this in an article by a group of Brooklyn OBGs who saw that many ethnic immigrants were petrified about their babies being born in the 8th month!

    So, apparently, Hazal,when confronted with a "medical" question, asked the most brilliant secular doctors in their time. They were very RATIONAL in their approach.

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    1. there are a number of possible reasons why a meme would be widely believed in the ancient world, but the most obvious and simplest (Occam's razor and all that... ) is that it was believed because it was true. in other words people believed what their observation demonstrated. the only reason to reject that explanation (and thereby label the chazon ish's perspective "anti rationalist") is if you have a prior ideological (ie non evidence based) commitment to believing that nature has not changed.

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    2. Not necessarily, people believed it because of the authority of Hyppocrates, and the "logic" of his argument based on his own observations, but first it was very difficult in these times to be sure of the date of procreation, some are going so far to say that women initiated this belief in order to get rid of illegitimate children which without care were doomed, but in any case the nature can't change in such a drastic manner that a less developed embryo should have been more viable than a more developed one, and then come to a state were the survival chance of a 7 month is 90% and a 8 month 95%, of such a thing אין חדש תחת השמש, I think that the chazon ish tried merely to avoid liglug chachamim. but as Bread from the land said there is no shame to accept the best of science available, but as Jean d'Orméson said : "science clear up the ignorance of yesterday and will became the ignorance of tomorrow".

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    3. My (extremely fraternal) twins were born at 7 months at 3.5 lbs and 2 lbs. They survived due to modern science in the NICU. The one who was 2 lbs would never have survived without that. I thank Hashem for creating human beings with the intellect to understand the world and create.

      Now I've got to get these wound-up toddlers to go to sleep.

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  12. Good post, point #2 in particular. Most of us don't realize that chazal are relatively late, historically speaking, and that the Greeks and Romans preceded them on many topics by many hundreds of years. Not just on scientific theories, but also (jarringly, to some) legal theories, methods of interpretation, and countless stories or legends.

    It's not the "fault" of anyone; few people today, of any faith, have any real knowledge of the classics.

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  13. Everyone knows where twins come from. The stork stops at the photocopier on the way out the door. There are two settings: identical and fraternal...

    Besides, who cares where twins come from as long as they get their shots.

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  14. For further discussion, see:
    Jeremy Brown, On Twins, and the Sperm that Splits in Two
    Edward Reichman, The Rabbinic Conception of Conception: An Exercise in Fertility

    I think you meant to write
    To see where I copied all the factual information in this post, see:
    Jeremy Brown, On Twins, and the Sperm that Splits in Two
    Edward Reichman, The Rabbinic Conception of Conception: An Exercise in Fertility

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  15. Please don't make any anachronism, you can find the same inaccuracies in the Greek authors, from which this statement was very likely lent.

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  16. What do you make of the gemara in Rosh Hashana where the sages report a tradition about the length of a day that turns out to be highly accurate?

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  17. I recall some years ago Natan Slifkin had a stereotypical post mocking Chazal's tradition that wisdom comes from the kishkes

    Had he even been up to date with contemporary science, he and his choir would have discovered that Chazal was avant garde re: gut microbes
    while showing off his obsolescence

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    1. Gut microbes contribute to our thinking? Granted, some people do their best thinking while sitting in a Certain Place...

      OK OK off color joking aside, the presence of the trillions of organisms that live in the colon does not negate the function of the brain. I could take your attempt one step further: there actually are neural connections in the intestines that are somewhat autonomous from the brain. But their only purpose is to operate the gut! Not to decide moral values! The idiom "knowing something in my gut" is a curious thing, as are many idioms, and probably relates to an emotional feeling being translated into a physical feeling (ever have butterflies in your stomach?).

      Anyway, the passuk (bochein k'layos) refers to kidneys, not intestines. If microbes take up residence in one's kidneys, one becomes rather painfully ill.

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  18. Keep it up natan! I know you are a lonely voice in the jungle, but you can never know what time will bring forth

    ReplyDelete

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