Since the process of abiogenesis happened once, I don't see why it shouldn't still be going on. Whatever process formed the first organism billions of years ago could assemble new organisms, completely unrelated to the first organism's "family," right? I don't know much about abiogenesis, so I please share your thoughts on this. I suppose the fact that all species have a common biochemistry would lead most people to argue that only one "family" exists. However, I believe some deep sea microbes have an alternate biochemistry, though I'm sure they still use RNA and DNA with the same nucleotides as DNA and RNA elsewhere. Still, for abiogenesis to have only happened once, it must be an event that, statistically, does not occur more often than at least every three or four billion years. And I suppose that could be the case, but I wonder if anyone has explored the possibility that it occurs more often.