Can you supply substantive evidence or demonstration that shows that natural
selection was the causal factor behind any of the major changes in life's
You wrote, "Natural selection can give a partial account for transitional
that they are better adapted than the ancestor for the niche they are
transitioning into. The variation must arise by mutation if it is going to
persist (unless the organism can transmit learned behavior). The fact that
a particular transitional form survives and goes on to evolve into the new
form might be largely attributed to natural selection."
My comment: This is not evidence, Dave. Take a real case from paleontology.
The modern blue whale is supposed to have evolved from some original
mammalian land ancestor. This is not a simple transition to another little
niche, as you know. This transition involves a long series of incipient
forms. The ancestor was presumably well adapted to its terrestrial
environment. Would the first mutation toward an eventual aquatic blue whale
been adaptive for the ancestor? It had to lose its well-adapted paws or
hooves for initially poorly adapted flippers. What niches did the incipient
forms fill? How did natural selection, which by definition only enhances
immediate adaptation, carry the incipient forms through so many inadaptive
Alternatively, isn't it just as rational to posit some unseen _directing_
force at work that drove the land-to-sea transition in spite of the passage
through many inadptive stages? Doesn't it seem to you that a long-range goal
was involved in guiding the whole passage?