Date: Fri, 31 May 2002
Evolution?
Thomas M. Miovas, Jr.
> From Michael Pomerantz
>
> I am not extremely knowledgeable in Evolution. I
> can see the direct connection between say, primates
> and human ... and I can somewhat understand some
> aspects of natural selection (but not all of that). But
> I have never understood how evolution explains
> how we got from say, frogs to human. How did we
> get from one species to an entirely new species? I
> have never seen any fossil records even remotely
> proving how we jumped from one species to the
> countless species in existence.
There have been some excellent science shows on the Discovery Channel, the
Science Channel, The Learning Channel and PBS regarding these sorts of
issues. One of them is even called "Evolution" which goes into a great deal
of detail (which I think is on PBS). You can check their web sites for more
information.
However, I think there are some false premises in the question.
Just because a species is considered (or classified) as lower than some
other species doesn't necessarily mean that the higher species came from
the lower one.
<HB: I don't think there is a factual, biological basis for a distinction
of "higher" and "lower." There is: earlier and later, and there is "simpler
and more complex." But "higher" and "lower" are informal, anthropomorphic
terms.>
In general, mammals came from an ancestor that was amphibious, but that
doesn't mean that mammals (including man) came from frogs. Both frogs and
man came from a previous species that was neither frog nor man, but some
type of amphibian.
And evolution doesn't go in one direction only -- say from amphibians to
mammals. Whales came from wolf-like animals that developed fins and
eventually lost their hind legs altogether. I know...whales are not
amphibians in the same sense that salamanders and frogs are, but they *are*
mammals that live entirely in the water, but have to breath air.
<HB: Evolution doesn't have a direction at all, let alone not
being uni-directional.>
One interesting thing brought up by the series "Evolution" was how the
bones of fish are connected and positioned (in relation to one another, not
overall) in much the same way as the skeleton of man. For instance, the
bones in the fins of fish correspond to the arm, wrist, and fingers of
humans -- minus a few extraneous bones; though they have found an extinct
amphibian that had, I think, seven or eight fingers.
In a similar manner, one of the episodes of one of the series showed quite
well how a reptile-like animal that stood on it's hind legs could become a
bird over time. Not only is the overall bone structure very similar, but
the motions of grasping for something running in front of it are remarkably
similar to the motion of the flapping wings of a bird. In essence, all that
the bipedal reptile-like animal needed were feathers and a lighter bone
structure to be able to take off in flight -- and they have found fossils
that show these changes occurring.
