On 18-Feb-2005, Scott Weiser wrote:

Could you please
post a reference to such a definition and also a reference that
clearly demonstrates that such definition is the only one that
is widely accepted by the scientific community.

Do you have an alternate theory?

You still didn't answer the request. But then, you can't.

Once again, it's because you don't know what you're talking about.

Which simply dismisses intelligent design while touting evolution without
explaining your version of evolution and without a rational analysis of my
question as to why sharks are still sharks 400 million years down the
evolutionary line.

You haven't identified what _my_ version of evolution is - in fact you
haven't identified what any version of evolution is and you haven't
demonstrated that _your_ version of "evolution" even exists in the
scientific community.

You understand nothing about evolution of any kind. You don't understand
sharks, either.

First of all, the only thing that remains constant in shark evolution is
gross morphological characteristics. In fact, over millions of years,
many shark species have died out and have been replaced by new species.
The fact is that DNA is changing all the time. We know that. However,
we know that most DNA plays no apparent role in morphology, so a mutation
is not always likely to result in a visible change. In fact, many
mutations produce no change at all. If you move beyond gross morphology,
sharks have changed a lot over time; Compare a great white to a whale
shark.

We know that DNA mutations occur in humans as well, and at a fairly quick
rate. In spite of that, there have been no morphological changes in
skeletal remains during the entire history of Homo Sapiens. No favourable
change means no lasting change.

Changes do not necessarily result in morphological differences. There is a
single species of iguana that swims - all others are dry land creatures. The
swimmer evolved as a result of a change in habitat from a change in ocean levels.
It lost its food supply and survived by learning how to swim and feed on the
bottom of the ocean. Only an expert can visually tell the difference between
the swimming and dry land species, since the morphology is much the same.

In the Amazon, there are flowering plants that produce a toxin used by the
Yanomami to hunt and fish (by putting the toxin on their spear and dart points).
There are two species - one that produces a strong toxin and one that produces
a weak one. There are _no_ morphological differences between the two.
Evolution isn't just about morphology.

As Rick has pointed out, Darwin did not observe constant change - he observed
statis. He observed that when an environment changes, an organism _may_ change
to match its new environment. This is due to DNA mutations or recombinations
that produce a favourable result in the new environment. Once that match
has established, there is not reason to change again and the organism retains
its current characteristics.

Mike