I like the theory that the amino acids which were essential for life to start came from outer space and got deposited when meteorites hit the Earth. I don’t know how much of it is theory and how much is evidence, though…
That’s an interesting question! I think it would be hard to prove either way. I’d however suspect that it probably started on Earth – for one life would have had to travel huge distances in space, on an asteroid most likely. It seems unlikely life could survive on one of these – perhaps the basic building blocks of life came from space…
Good one! Well the idea that life originated in space is usually based around the idea that we do see some molecules associated with life out there in space. We don’t see life itself out there of course, just some of the molecules that make up life. Some people have proposed that these molecules – or even basic lifeforms – could have hitched a ride to Earth on a comet. There were a lot of collisions with comets and other rocky things back in the early days of the solar system.
This theory is called panspermia, but it is very hard to find evidence for it one way or the other. It is simpler to assume the molecules were already around on Earth – but panspermia isn’t impossible.
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