[ericbarrett]

The fossil record indicates life on Earth appeared no later than about 800,000,000 years after it first formed, and possibly much sooner.

While there’s no real evidence for panspermia, it is a fun topic to read about. I recall one hypothesis is that DNA (or RNA) based life evolved shortly after the Big Bang (500,000 years?) when the universe was a balmy lumpy-gas bath of 0-100C. If this were true, it would follow that life is as pervasive as the cosmic background radiation and we should expect to find it in every crevice. Mind-bending.

[ardy42]

> I recall one hypothesis is that DNA (or RNA) based life evolved shortly after the Big Bang (500,000 years?) when the universe was a balmy lumpy-gas bath of 0-100C. If this were true, it would follow that life is as pervasive as the cosmic background radiation and we should expect to find it in every crevice. Mind-bending.

That's pretty unbelievable, since at that time stars hadn't formed to create heavier elements, so the elements available were hydrogen, helium, and a little bit of lithium. DNA is mostly carbon and nitrogen.