"Scott Lurndal" wrote in message
. ..
Let's see. The mantle contains U235 and Thorium, both of which
produce gammas during decay. The earth is continually bombarded
by cosmic radiation, which can easily tweak a chromosome or gene pair.
DNA is also damaged by environmental effects (poisons, etc). Combining
any two sets of genes results in a new set of genes.

2) How survivable was a "between-thing"? For example, one of those
between-things that was *almost* a bird -- it couldn't run fast and it
couldn't fly -- so how could enough of them survive long enough to evolve
into something good enough to survive?

The survivable "between things" survive, those that can't, don't. That's
the _whole point_ of evolutionary theory.


Interestingly enough, it appears that genes - then self-replicating protein
encoders rather than a definable life form - may well have aggregated from
several sources, each supporting the other in formation of something
approaching life.

The easiest answer to the "where's the missing link" query is "in the
mirror." It may not show in your face, but it's in your genes. Pretty much
all that was tried and discarded is still available, even if it is
suppressed.