This question may seem a bit preposterous at first glance, but please bear with me because I think that, although its genesis was perhaps a bit outlandish and might even offend some sensibilities, it really hinges on a fundamental understanding of the interplay of kashrut, halakha, and the spirit of both, which we realized we were both perhaps lacking in. My friend was reading a science fiction story in which a human being was capable of laying an egg. I argued that such an egg would not be kosher, while my friend argued that because there was no explicit kashrut prohibition on such an egg it was indeed kosher, but went on to concede that it would of course violate halakha around menstrual impurity. My question is, would such an egg be kosher? Again, I realize this is a strange question, but for me it cuts to the core of what is kosher and what is treif. Should we judge as treif only things explicitly laid out in the Kashrut as such, or should we apply the spirit of the halakha to things not encountered by our ancestors? Fast-progressing technology make the importance of such judgements highly relevant, for example there has recently been the first "lab-grown hamburger". A futuristic lab-grown bacon is likely not too far away, and I believe the spirit of the kashrut would prohibit its consumption even though, technically, it was never part of a pig. So again I ask, would such an egg be kosher? Thanks for your time, Richard.
Firstly, a person should be disgusted with the idea of eating even derivatives from humans. Rav Kook explains that even eating animals should morally disgust us, and God only begrudgingly allowed Noah to eat meat after the flood (Breishit 9, 3), in order to clarify the differentiation between man and beast. Despite Darwin, man is created in the image of God and we are qualitatively different from animals in our morality, family life, speech, free will, clothing, eating, manners, and really everything. The flood was a punishment for those who treated humans like animals, and slept with animals rather than humans. The constructive educational process included God The constructive educational process included God driving a significant wedge between the two, clarifying to man through allowing meat: “humans you marry and don’t eat, animals you eat and don’t marry!” Even evolution believes that the future (even according to science-fiction!) should see man advancing forward to the level of the original ideal before the flood, when we were vegetarians, and surely not retreating backward morally, to start eating derivatives of humans! Halachically, cannibalism itself isn’t allowed, because there’s a positive (aseh) prohibition to eat only kosher animals (Rambam, Ma’achalot Asurot, 2, 3; Rama Y.D. 79, 1; Bach, etc.). Additionally, there’s a prohibition on defiling or using a dead human body (Y.D. 349), and also, we are prohibited from eating anything disgusting (Bal Tishaktzu, Shulchan Aruch Y.D. 116, 6). Nevertheless, technically, there is no explicit negative (!) Torah prohibition (lo ta’aseh). This had to be the case, for the rule is that derivatives from a non-kosher creature (if there’s a negative prohibition) are non-kosher (e.g. pig’s milk), and we all know that a mother’s milk or a person’s fingernails (it’s not uncommon for some to bite them…), have to be kosher. Accordingly, the poskim would have to decide if a human egg is considered part of the body and accordingly, an explicit positive prohibition (aseh) or, as is more likely, it may be considered just a derivative (for like milk, it is meant to eventually leave the body, and is not an inherent organ) which would technically be kosher (and there’s even no problem of menstrual impurity), but even then, would still be prohibited for it’s considered disgusting to eat. Lastly, I hope you will be just as eager and not embarrassed in the future, to ask practical halachic questions, as well! With Love of Israel, Rav Ari Shvat