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Re: Dinosaurs to birds
On Sat, 23 Jan 1999 Dinogeorge@aol.com wrote:
> Perhaps I can illustrate the idea of "luck" here a little better. Consider the
> California super lottery, wherein the numbers are chosen via a device that
> circulates several lightweight numbered balls in a container until one of them
> pops out. If we knew the >exact< initial conditions and the >exact< locations
> and magnitudes of the circulating forces, we could predict which ball would
> pop out, thereby removing the "luck."
The analogy is somewhat tortured. For starters, the balls (species) are
not passive entities. The environmental "device" may have in _many_ cases
little to do with the outcome. That was the lesson of the recent
Genyornis extinction discovery. As such, species are constantly
influencing their own success and likelyhood of survival by the quality of
adaptations they are able to come up with. And for many of these it is
possible to discern distinct _trends_, i.e., we can tell who the winners
might be _before_ the outcome is announced. And some of these are
apparent in birds. There is a trend to better flight characteristics, to
rapid growth. If one can see these things _before_ the K/T, it might be
worth it to put money on these species to appear after the K/T.
> But knowing the initial conditions to
> the required exactitude is impossible (due, among other things, to
> Heisenberg's Uncertainty Principle, not just the secrecy of the people running
> the lottery); the best we can do is describe the behavior of the balls in
> general terms as "chaotic."
But speciations, extinctions (often the flip side of the speciation coin),
adaptive radiations, morphologies are all _directional_ not chaotic or
random. Indeed, in Dawkin's language, species are quasi-designed. The
relationship between natural selection and the environment has always been
difficult to comprehend. In one sense species are shaped by their
environment (remembering, though, that other species are part of their
environment), in another sense as species become more complex they are
able to respond to environmental changes, they have more flexibility. As
time goes on species become more immune to the vagaries of the
environment. And so the more this is true, the more predictable might be
> In the case of extinctions, the details of the mechanisms are lost from the
> fossil record. There is no way to confirm just how the bolide impact killed
> off each individual organism, which is what you would have to do in order to
> advance a hypothesis beyond "luck."
But luck is itself an hypothesis which has been advanced! In
absence of evidence, claiming it as a default hypothesis is just not fair.
Indeed, given the directional nature of evolution if any hypothesis
deserves special treatment is it this: species possess heritable
morphologies and behaviors. Some of these allow species to survive and
reproduce at higher rates than other species. If an adaptive trend is
discernible before an extinction event, and the species possessing these
adaptations are the survivors of the event, an _excellent_ starting
hypothesis is that these adaptations account for their survival.
Of course this may not be true. But I just don't see how you can claim as
a default that they had _nothing_ to do with it.