Stem cells used in medical research generally come from fertility clinics, which produce more embryos than they can use. This isn't an accident -- it is essential to their mission of helping people have babies. Often these are "test tube babies": the product of an egg fertilized in the lab and then implanted in a womb to develop until birth. Controversy about test-tube babies has all but disappeared. Vague science-fiction alarms have been crushed by the practical evidence, and potential political backlash, of grateful, happy parents.
In any particular case, fertility clinics try to produce more embryos than they intend to implant. Then -- like the Yale admissions office (only more accurately) -- they pick and choose among the candidates, looking for qualities that make for a better human being. If you don't get into Yale, you have the choice of attending a different college. If the fertility clinic rejects you, you get flushed away -- or maybe frozen until the day you can be discarded without controversy.
And fate isn't much kinder to the embryos that make this first cut. Usually several of them are implanted in the hope that one will survive. Or, to put it another way, in the hope that all but one will not survive. And fertility doctors do their ruthless best to make these hopes come true.
In short, if embryos are human beings with full human rights, fertility clinics are death camps -- with a side order of cold-blooded eugenics. No one who truly believes in the humanity of embryos could possibly think otherwise.
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