[wendy1946]

What about the possibility of life being seeded on Earth from a celestial collision?

Any sort of an ancient alien theory as to life getting onto Earth originally just kicks the can a block or two down the road as far as evolution/evoloserism goes. No such theory can answer the mail for the Haldane dilemma or the amounts of time it would actually take for our present biosphere to arise ala Darwin/Gould if that were possible (it isn't).

[numberonepal]

There is evidence of a "jump" in human evolution - possibly brought on by genetic manipulation.

Haldane's Dilemma shows that not "enough" genes could have substituted in the human species since the last common ancestor with other apes.