"Please remember that evolutionary theory is only an attempt to explain the diversity of life, but not the origin of life."
If that is true then why does evolution postulate Universal Common Ancestry? If it (a) does not postulate the origin of life, and (b) cannot _prove_ the links between the kingdoms (or even between many groups of animals within the kingdoms, like turtles and bats), then why is universal common ancestry part of evolution?
The doctrine of universal common ancestry would make sense if there were a theory of abiogenesis which required it. However, without one, the only reason to suppose universal common ancestry is materialist philosophy.
http://crevo.blogspot.com/2005/04/overselling-universal-common-ancestry.html
Common descent is supported by numerous independent lines of evidence, the most convincing of which is the same kind of DNA evidence that establishes parenthood in the courts.