The previous Ashkenazi Chief Rabbi of Israel, Rabbi Israel Lau, stated in an interview: “The Torah gave a specific dispensation for doctors to use their knowledge to cure, and even to lengthen life, but the formation of new life goes way beyond that. We have no permission to enter the domain of the Creator on questions of life and death.”
We do, however, find some precedents in our tradition for “engineering” which is not strictly for the purpose of healing. For instance the Talmud says that the runners of King David, had operations on their feet, and had their spleens removed, (according to Rashi, neutralized by drugs), in order to increase their efficiency as runners. It is possible to argue that these medical procedures imbued the runners with some tangible health benefits (fitness, endurance) and therefore were permitted, even though the runners were not ill.
It is interesting to note that a great 13th century rabbi, Menachem Meiri, writes that making creatures asexually is permitted since anything performed naturally is not defined as a prohibited act of kishuf (sorcery). His comments from some 800 years ago suggest that one who understands how nature functions is aware of the fact that it is possible to produce beings asexually, such as the cloning of living beings.
Also, according to some commentaries the intervention of Jacob in the breeding of his sheep was a naturalistic manipulation that was not miraculous (Genesis 30:38-39). “In the watering trough where the sheep came to drink, Jacob set up striped sticks... and the sheep became stimulated when seeing the sticks, and when they gave birth, their offspring were striped, flecked and blotched.”
In addition the Talmud relates that the Sages were able to create living beings through their knowledge of the Kabbalah: “Rabbi Chanina and Rabbi Oshia sat every Friday afternoon and studied the Book of Formation. Through their study they created a prime calf, and they ate it. Rava created a person and sent him to Rabbi Zeira. Rabbi Zeira tried to speak to the creature, but the creature was unable to respond. Rabbi Zeira realized then that the creature was a creation of Rava and he returned it to dust”
These creatures, as is evidenced by the creature’s inability to speak, did not have souls and were not really human. However, a child born to a human mother, from a human embryo, would without doubt be a full-fledged human being with its own unique soul.
