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> Even the lifeforms that we do know of, occupy a very broad spectrum in all metrics, existing at all sorts of extremes. But all lifeforms we know evolved from
by Scarblac 9y ago
> Even the lifeforms that we do know of, occupy a very broad spectrum in all metrics, existing at all sorts of extremes.
But all lifeforms we know evolved from one common ancestor, it's one tree of life. As far as we know life evolved here only once.
So we know that once life happens it can become completely ubiquitous, but it doesn't say anything about that crucial first step.
- Retric 9y ago> But all lifeforms That's not nessisarily true. Single celled organisms have a rather fluid exchange of genetic information even our 'single cells' are really several different organisms. It's possible life evolved many times on earth and current single celled organisms and thus all life has a mismatch of ancestors. Further, life may regularly evolve even today, but simply get eaten due to the stiff competition. PS: We know life evolved at least once, but the high end could be multiple times a second on earth.
- padobson 9y ago> It's possible life evolved many times on earth It's also possible it evolved elsewhere and rode here on a meteor - or was brought here by some other lifeform several orders of magnitude more advanced than us, using earth as their own cosmic terrarium.
- Retric 9y agoWhy not both. We could also be descendants of an invasive alien species that killed off all of Earth's native lifeforms. It's good practice to assume the simplest possible solution. However, the full range of the full range of what might have happened is ridiculously large.