Question: Did every animal in the world evolve from some kind of bacteria when the Earth was brought into existence?

Tess Newman answered on 1 May 2012:

The first kind of ‘organism’ on Earth would likely have been a kind of DNA ancestor. This would have been a chain of simple protein molecules, that would have managed to replicate itself. Eventually, over time, some types would have built protective layers around themselves, or learnt how to break up other chains to use the proteins for itself . Over a long period of time, these would evolve into single-celled organisms, such as bacteria, that are the ancestors of life on earth

(If you want to know more about this read ‘The Selfish Gene’ by Richard Dawkins)