Front end loading (Introduction)

by Carl, Friday, October 03, 2008, 18:28 (5676 days ago) @ David Turell

I found a science daily article titled "MicroRNAs Found In Animals That Appeared A Billion Years Ago" at
 http://www.sciencedaily.com/releases/2008/10/081001145018.htm 
In some of David's post, he has referred to ancient RNA and DNA. Since genetic material doesn't survive in fossils (except small amounts in T-Rex) how can scientists talk about ancient genes. I can see the possibility of finding identical genes in all species within a clade and extrapolating back to the genome for their last common ancestor, but I don't know if that is how it is done, and I don't see how you can then talk about the evolution of that RNA, since all you have is the final product. Does anyone know?
Another thought. David talks of "survival of the fittest" being circular. A way to think of it is as a description of a process - "survival of the fittest", "random survival" and "survival of the least fit" in the case of game animals and trophy hunters.