According to Anselm, the answer might be “No.” In Cur Deus Homo (“On Why God Became Man”) 2.8, having just argued for why man’s restoration from sin could only be accomplished by a God-Man, Anselm explains why it was further necessary that the human nature assumed by God in the Incarnation should be descended from Adam.
But if he creates a new man who is not from the race of Adam, this new man will not belong to the human race which is descended from Adam. Consequently, he will not have an obligation to give recompense on behalf of this race, because he will not be from it. For, just as it is right that it should be a human being who should pay recompense for the guilt of humanity, it is likewise necessary that the person paying recompense should be identical with the sinner, or a member of the same race.
For Anselm, Adam’s race can only be redeemed by “one of its own,” and so for the atonement to be effective, it must be accomplished by God becoming incarnate in someone actually born of Adam’s race. Anselm’s argument, however, is fascinating as much for what it might say about the possibility of being human as it is for what it says about the possibility of the atonement. Anselm denies that any “new man” who is not a biological descendant of Adam can be of the “same race” of Adam. It’s possible that by “race” (genus) Anselm simply means Adam’s genealogical line, and not the species of humanity itself. If, however, we take “race” to mean the human race, the philosophical and theological implications are nothing short of explosive.
If being either Adam or a descendant of Adam is necessary for being of the same species as Adam, it means that the only way to be human is to be related to Adam. Being a genealogical descendant of Adam is the very possibility of being human. If so, then the problem with Anselm’s hypothetical “new man” is that, by not being a member of Adam’s race, he is not really a man at all, but an alien, something other than man, a kind of “non man,” whatever his biological similarities to man might be. (This, incidentally, might give us another perspective on why, according to Aquinas’s later argument, every angel is its own, distinct species: not being individuated by matter, angels must belong to different species in order to be differentiated from each other. If we take our cue from Anselm, not just material embodiment, but also genealogical kinship, is necessary for two things to belong to a common species.) According to Hellenistic metaphysics, a thing’s genealogical pedigree was accidental to its being, to its whatness. In Anselm we see the possibility of a more Hebraic metaphysics, one in which genealogy is not accidental, but essential. Much as you being the son or daughter of your specific parents is necessary for you to have been at all (there is no “possible” you, even for God, except as the child of your parents), so it might turn out that there is not any possibility (even for God) of being human except as a descendant of Adam. This wouldn’t be because of some kind of limitation, necessity, or constraint on God, but rather because this would be simply what God himself had determined what it means to be human (just as he determined that what it means to be you is to be a specific child of your parents). For God, there is no such thing as being human without being either Adam, his wife, or one of their progeny. (Here we also seem to have part of the metaphysical significance of Eve being taken from Adam’s side, so that she also might be a “member of the same race.” Adam is the possibility of Eve–no Eve except as the one taken from Adam’s side–and Adam and Eve together are the possibility of every subsequent human being.) What this would further mean is that there is no absolute, abstract, Augustinian “divine idea” of man-as-such for God, or if there is, Adam himself is that idea: God doesn’t know or determine “man” as a possibility except as a member of the race of Adam. Adam, therefore, is not just the father of the human race, he is the very archetype of the human race. When he fell, the very possibility of being human fell along with him. This is the modal metaphysics (or at least part of it) behind original sin, but also behind our salvation. For the human race to be restored, it would need to receive a new archetype, one who was at once a member of the “old” human race and the very possibility of a new one. It turns out, consequently, that when we say that Jesus is the “new humanity,” we are actually being as literal as one can possibly be. As the Second Adam, Jesus, not figuratively, but literally and metaphysically is what it now means to be human.