Question: How did life begin?

Paul O'Mahoney answered on 8 Mar 2016:

There’s some debate about this, and I’m not sure if anyone is 100% sure, but this is one theory I have read (if I can remember correctly!):

Most life started out as tiny single celled organisms, but there were also things called prokaryotes too. Eventually, one of the prokaryotes attached itself to a cell, and got eaten up by the cell. Instead of being destroyed, they formed a symbiotic relationship – meaning they each gained something from it. Basically, these prokaryotes became the mitochondria in our cells, which are often called the power factories in cells. This gave the cell lot of energy, and allowed it to do more complex things and eventually form multi cellular organisms, and eventually humans!