Brian Williams wrote: > > >> 3- What is the latest estimate of the age of the earth, and consequestly the earliest life form? > > > >Sorry, but I forgot. I think it is about 20 billion years though. > > Wrong! By most estimates, the UNIVERSE isn't even 20 billion years > old. The earth is about 4.5 billion years old, and the earliest life > forms appeared about 500 million years ago.
The earth is about 4.5 billion years old, but life (depending on your defintion)appeared much earlier than 500 million years ago. The oldest fossils (stromatolites) are 3.5 billion years old. The "universal ancestor" that gave rise to archaebacteria, eubacteria, and the nuclear line was around 3.8 billion years ago if I have my numbers right.