The possibilities of genetic engineering continue to grow. May a Jewish scientist genetically engineer things?
Genetic engineering has been cited by some as both halachically acceptable and problematic in several respects:
- Stem Cell Research -- Unlike some other religions, Judaism does not define a fetus as a human being with full rights until after 40 days of gestation. Yevamos 69a; Nidda 30b. But see Rebbe's position at Sanhedrin 91a (holding that the soul is created at gestation). Accordingly, most poskim permit Jewish scientists to do research on embryo stem cells that are less than 40 days since gestation. Sources: RCA Statement and a lecture I heard from Rabbi Dr. Barry Fruendel.
- Cloning -- Research indicates that, subject to more safety improvements, it will be possible for a woman to take her own skin or bone-marrow cells and create a gamete-like cells with only 23 chromosomes that could be attached to the woman's own egg cell to create a perfect copy of herself. This could be a violation of the concept raised in Niddah 30 that there are three partners to the creation of a new soul, a man, a woman and Hashem. Cloning would appear to intentionally by-pass part of this Divine process. To my knowledge, this has only been studied by our sages from the perspective of unmarried women using in vitro fertilization to have children without having relations. But the decisions of Rabbi Shlomo Zalman Auerbach, zt'l, Nishmat Avraham, vol. 4, Even haezer 1:3, and Rav Moshe Feinstein, zt'l, cited in R.V. Grazi and J.B. Wolowelsky, “Parenthood from the Grave,” The Jewish Spectator 65:4 (Spring 2001, Aviv 5761), appear more concerned that the sperm donor might not be Jewish. So I am unaware of a precedential decision that is directly on point here.
- Transgenic Species -- Already we are seeing the use of DNA material from foreign species injected into the cellular structures of animals and plants to alter those species into what is called a transgenic species -- and also the enhancement of an animal's DNA with the DNA of other creatures of its species, a process called cisgenic. While cisgenic animals and plants are not problematic, the creation of transgenic species crosses into the area of kilayim. Leviticus 19:19 states: "You shall keep my statutes. You shall not let your animal mate with a different species; you shall not sow your field with different species of plants." Most sages appear to agree that, with respect to animals, the prohibition only applies to actual inter-breeding of mixed species. Taking the genetic material of different animal species and making transfers on the cellular level is generally accepted. Akiva Wolff, "Jewish Perspectives on Genetic Engineering," Jerusalem Center for Public Affairs (Oct. 2001). However, there are differing opinions about transgenic plant species. Id.
- Transgenic Animals With Human DNA -- Some scientists believe that research on brain diseases such as Alzheimer's and Parkinson's requires using stem cells to creating lab animals (apes in particular) with genetically human brains. Beyond the ethical considerations raised in the science fiction movie, Planet of the Apes, some commentators have suggested that the rabbis' current view that transgenic animals are not subject to kilayim should be reconsidered if their view is based on the assumption that the animals will be sterile. If they can be made to reproduce with human-type gonads, writes Leora Perlow and John D. Loike (separately), it may be possible that in a few generations the grandchildren of the original transgenic ape could mate with a human. Whereas the species of cross-bred animals was always decided by the mother of the animal (Bechoros 5b), what do we call the product of a transgenic advanced ape male and a human female? And what halachic status will the product have?
And the reason for kilayim is that God created the different species in the world for all the different kinds of souls, in plants and in those that have the animative soul, and he gave them the power of reproduction, that the species should exist for eternity, for as long as He should desire the existence of the world, and He ordered that that power should reproduce the species and never ever change, as is written (in Bereishit) concerning each (species), "l'mineihu" (for its species). And this is the reason that we breed animals in order to preserve the species, just as men come unto women for (the purpose of) reproduction. But one who intermixes two species changes and negates the act of creation, as though he thinks that God did not complete His world sufficiently, and he wishes to assist creation by adding creatures to it.
Genetic engineering is even worse in this regard since you are completely changing the organism.
But this needs to be tempered with the knowledge that virtually nothing we eat today is like Hashem made it. The wheat we eat today is completely different from what they ate in ancient times. (They ate what we call wild Emmer wheat, we eat durum wheat hybridized with goat grass.) The wheat has changed to the point that it can not even self propagate - it requires humans to plant it. (This change is why ancient Matzah was soft like pita, and ours is hard.)
Our cows are much much larger than theirs, same for chickens and turkeys. (Interestingly modern turkeys also can not reproduce on their own.)
The soft corn we eat did not exist in the past. (And to continue the theme, soft corn also can not propagate on its own.)
In fact, I feel pretty confident in the saying that not a single vegetable in the supermarket is like Hashem made it - and not minor changes either. Major differences in the taste, size, how long it takes to grow.
But, all this needs to understood in light of the question of how much change is called change.
After all, it is permitted to graft together plants together if they are of similar species. For example the wheat hybridization I mentioned above is permitted.
So, in that light the plants and animals we eat have not changed enough to be called new species. And genetic engineering usually limits itself to small changes, which are not enough to make a new species.
Not at all. As the Yerushalmi (Nedarim 9:1) asks rhetorically:
לא דייך מה שאסרה תורה אלא שאתה אוסר עליך דברים אחרים
Is what the Torah forbade not enough for you, that you [seek to] forbid other things upon yourself?
As for the reason for the prohibition on kil'ayim, no one claims to have the definitive answer. It is not considered a moral imperative, but rather a chok; a rule without a known reason. We can speculate from here till tomorrow - as Maimonides does in his guide - but it's only speculation. When it comes to deciding halachic matters, such speculation without proof has no place.