I found a very interesting article about 'life forms' that do not require DNA. It's still controversial, but it could shine some light at how to really define a life form. And it would point in the direction of abiogenesis.
Here's the link:
http://news.bbc.co.uk/1/hi/sci/tech/3729487.stm
Let me know what you think.
Here's a quote from the article:
"One of the questions we always get back is: 'well, how do you know it's alive if it doesn't have a unique DNA sequence?' This is true," Dr Miller explained.
"But if you go back to how we defined life prior to our knowing about DNA, our criteria was that things multiplied in culture. This is what we have."
In 1996, nannobacteria came to the attention of the world's media when scientists announced they had found fossils in a Martian meteorite of what appeared to be nano-sized bacteria.