[TimM]

I'd like to read the original article. I'm sure these popularized science mags omit and distort tons of critical details.

That said, it sounds even more plausible if you consider the possibility that microbial life or protolife in the form of self-replicating molecules form easily and under a variety of conditions. Life or protolife could have formed independently on Earth and some of the comets and say, Mars and other bodies. Earth could have been seeded many times, and the DNA based life we see today may have just been the kind that out competed all the others. Now there are far fewer comets impacting Earth so the likelihood we are still being seeded is much lower.