Question: how did life begin?

Leah Fitzsimmons answered on 18 Mar 2014:

It is impossible to know for sure because it was so long ago that we have very little evidence, but there are several theories that people are following up to try and figure this out. What we can be certain about is that life will have built up over time, from very simple single cells to more and more complex organisms.
There was a very famous experiment that was carried out in 1953 that showed that when you have an inactive mixture of the individual bits of living things, you can make more complex molecules when you pass electricity through the mixture. This lead to a theory that the first complex molecules that we could think of as early life might have been made during enormous electrical storms several billion years ago.
One of the other most popular theories is that Earth has never had the right conditions for complex molecules to come about, but instead they were brought here on an asteroid. Only once these molecules got to Earth, with it’s unique atmosphere, could these primitive forms of life become even as complicated as a single cell.