Nobody knows how life got started on Earth. The normally accepted theory is that various molecules got randomly combined in the energy rich environment and then evolution automatically took place of the rest. The "organic soup" experiment did show that organic compounds could be produced with relative ease but the pure odds of them combining into something capable of replicating itself are astronomical and unless there is some factor making replicating compounds more likely, would be incredibly unlikely to happen. within the lifetime of the universe.
However what we do know, as this diagram shows, is that life developed within 500 million years of the planet's formation - almost as soon as the mantle had cooled enough for it to survive. If it was a purely random accident the odds of it happening that quickly are small. I see 3 alternatives:
I dunno. This is more complicated than saying how the world can be run.
- That there is some unknown chemical relationship making life bearing compounds more likely so that the formation of life by accident is likely - it would have to be a considerable effect to bring the odds down from unlikely on millions of planets in the life of the universe to likely on 1 within merely hundreds of millions of years.
- That life originated elsewhere and has been carried, at bacterial size, everywhere - if so such life should be endemic everywhere there are or have been conditions that can support it. This is known as Panspermia and fits what we know. Thus we should expect to find bacterial type life on Mars whenever humanity gets off its arse and seriously looks. The probes so far have produced results which cannot be explained as finding life as we know it, nor explained as having found nothing. In this case the level of our ignorance is plain, and considering that we are willing to spend trillions killing people, inexcusable.
- That we live in a multiverse with an infinite number of universes, or at least potential ones. In that case we are bound to live in a universe where life formed because otherwise we wouldn't be here to see it. I believe we do live in such a universe. However in such case there is no particular reason life should have formed so quickly. We will always now be 4 billion years from the creation of life and there would be no real difference if the Earth had been around for 4 billion years rather than 0.5 bn. It would mean that we only had 2.5 bn rather than 5 to go before the sun explodes but that does not affect our ability to investigate the universe now. If this, rather than the panspermia theory were true we would not expect to find life on Mars.
However what also strikes me is that the formation of life may not be the difficult trick.
Looks to me like the difficult and improbable stuff wasn't the formation of life or the evolution of humans but the evolution of anything bigger than a microbe. Go figure.
- 0.5 bn years, or less, possibly much less for life to form.
- 1 bn to start photosynthesis
- 1 bn to develop a cell nucleus.
- 1 bn to produce multi-cellular life.
- 0.5 bn to get up to the reptiles.
- 0.2 bn to get to dinosaurs and mammals.
- & 0.005bn - maximum time to get from the chimpanzees to us.