  There are several possible replies, though. First, it is not clear  that the options in twinning are exhausted by the three possibilities articulated above. A fourth possible option, it seems, is that of the four-dimensionalist, who can maintain that the embryo is a human  being from the moment of conception by saying that the pre-twinning  temporal parts of both Barney and Claire simply overlapped,  i.e., what we called Adam was really a shared stage in the lives of  both Barney and Claire. McMahan, for one, simply dismisses this  possibility as absurd (McMahan 2002, 26), but it is not clear why,  especially given that it is a straightforward application of a  powerful metaphysical theory that has quite a bit of independent  support (despite having its own set of problems, discussed earlier).  Second, the implications involved may not be as bad as indicated. For one thing, “death by twinning,” while still a kind of  death, may not be of a kind warranting the same sort of mourning  typically expected to accompany regular “bodily” death.  Furthermore, this kind of ceasing to exist, if it is a different kind of event than that of regular death, perhaps should not be expected  to have the same kind of conditions – like the leaving of  earthly remains – as regular death either. Consider how we  think of the similar “deaths” of splitting amoebas  (Ibid., 27).