I have occasionally mentioned this here before, but since today and tomorrow bring us a rare event - the succession of one emperor by another in Japan - I thought it would be timely to bring this up again.
Sometimes the claim is made that, because the biblical genealogies come with specific names and ages, this demonstrates their historicity. The underlying assumption seems to be that genealogies with specific names and ages (or dates) must therefore be intended to be historical and must function historically; and that if they are falsified by critical study, their function is eviscerated and whatever purpose they serve is therefore fatally undermined. A close corollary to this seems to be the assumption that a genealogy with a verified historical referent at one end, must therefore be equally historical throughout - or else errancy and evisceration follow.
To demonstrate this is not universally the case, though, and therefore might not necessarily be the case with the biblical genealogies, we only need to look at the genealogy of the Japanese Imperial House. This genealogy terminates with the very-much-historical Akihito (now Naruhito), in the present day, preceded by a succession of equally historical emperors and dates going back many generations. But if you go back far enough, the genealogy gradually encompasses figures for which no historical referent can be found - and eventually the figures become quite mythological. Jimmu, the first emperor in the line, is entirely legendary and in turn descended from the sun goddess Amaterasu.
Yet the genealogy is maintained and respected by the Imperial House and the Japanese people to this day, despite its ahistoricity. Why? Perhaps because its function is not just as a ledger of recent emperors, but as a national statement about the unity of the Japanese people and the legitimacy of their sovereign: one people and one island nation, under one line of heads-of-state, founded and blessed by heaven, since time eternal.
So too, then, could not something similar be the case with the biblical genealogies? At the very least, the idea that the historical falsification of a genealogy renders the genealogy errant and hence worthless, is falsified by this example. After all, I don’t see anyone saying that the Japanese imperial genealogy is false and therefore it cheapens, weakens or undermines Japanese imperial tradition, legitimacy, etc. Nor on the other side do I see Japanese imperial apologists rising-up to defend the historicity of Jimmu and the other emperors. The whole thing is a non-controversy, it seems, so why need it be a controversy for Christians?
PS: The Japanese imperial genealogy: https://en.wikipedia.org/wiki/Japanese_imperial_family_tree