Natural Science Forum / Biology / Paleontology / January 2005

Philip Bowles wrote:

I'll refer you to your own statement above - "Form a theory as to what
may be true". Science isn't a matter of watching and describing what
happens, it's a process of finding explanations for things that are
observed and that have happened. In the case of evolution, trends that
needed explaining in Darwin's included biogeography (why are related
species found in different environments close to one another while
unrelated species are found in similar environments on the other side
of the world? A creator with a free hand would logically be predicted
to have placed similar or the same tropical species in the tropics
throughout the world, rather than, say, boas in one part and pythons
in another), paleontology (why do species resembling older species
rarely never occur with those species, and why are younger species
more similar to living examples of their kind?), taxonomy (why do
species fall into neat taxonomic groups at all?) and embryology (why
do young amphibians, reptiles, birds and mammals all resemble each
other in the earliest embryonic stage?). Theories that didn't invoke
some kind of evolutionary mechanism had to fall back on "God moves in
mysterious ways" to explain all of these findings, which is not a
scientific approach.

This isn't strictly true - evolution has been observed in pathogens
and the natural selection that leads to the development of new species
(i.e. evolution in progress) in animals. It probably is true that no
one has carried out a sustained study on natural animal populations
for long enough to observe speciation (although it is known to have
happened on historical timescales), but that isn't a necessary
condition of proving the theory, any more than you have to travel
close to the speed of light to prove relativity, despite the fact that
it predicts certain things will happen when you do.

You have forgotten to ask one crucial question - what are the
predictions made by evolutionary theory? Note the plural - no theory
makes only a single prediction. No theory stands on the success of
just one of its predictions, and no theory has been exhaustively
subjected to every possible prediction arising out of it. Nor is
waiting and watching to see what happens the only way of testing a
theory's predictions - in one of the posts I gave a link to I listed a
number of lines of evidence that have been used to confirm what would
be predicted if new species did indeed arise by evolution. No one
makes the prediction "If evolutionary theory is true, we can expect a
new species to arise out of that species at some stage in the distant
future"; it isn't realistically testable, any more than it's realistic
to test "We predict that the sun will die in about 5 billion years".
What people do predict are such things as:

"If species arise by evolution from other species, we can expect a
fossil species to be found with the characteristics of both ape-like
ancestors and human-like descendants"

"If natural selection promotes survival of the fittest, we can expect
a proportion of this pathogenic species to develop resistance to
certain drugs"

"If co-evolution is a real phenomenon, then this orchid with a long
nectar tube is associated with a moth with a proboscis exactly long
enough to feed from it"

And so on and so on. That's the scientific method in action. To turn
it on its head, we can ask "If species do not arise by evolution from
other species, why do we find species with both ape-like and
human-like characteristics?". "If natural selection does not promote
survival of the fittest, how does drug-resistant TB emerge?" and so on
and so forth. Evolution is accepted because it is the best and most
plausible explanation for observed phenomena and, in one form or
another, has passed every test it has been subjected to.

Your thoughts betray a lack of understanding of how scientific enquiry
proceeds, and I haven't seen you clamouring for equally unrealistic
proofs of general relativity or other scientific theories.

Note again the reference to "Darwinian evolutionary theory", not
modern evolutionary theory. Darwin's model can be questioned on the
basis that it didn't make testable predictions about the mechanism of
inheritance, and important concepts were poorly-defined - in some ways
it was more of an outline of the general process than a detailed
theory. A hundred and fifty years (close enough) of research into
evolution has developed and refined these ideas - you wouldn't attack
some aspect of medical research on the basis that, say, Pasteur was
wrong or vague about something, and it's daft to criticise evolution
based on nothing but Darwin's own work.

I was under the impression it was taught as science. Interesting
point, though: What would you have taught in science lessons? Science
doesn't recognise 'fact' in its terminology -  we'd have to ban the
theories of gravitation, electricity, nuclear physics, general
relativity and quantum mechanics, not to mention pretty much the
entirety of cosmology (which is theoretical with very little grounding
in prediction or experiment).

It can more or less be included in the discussion of drug resistance
evolving in pathogens (and to an extent the evolution of
immuno-responses in humans, an increasing number of whom are naturally
resistant to it).

Hiv per se defy the theory of

How, precisely?

You don't keep very up to date, do you? HIV is on the rise in the
developed world, largely because of acquired resistance to most drugs
on the market. HIV research is ongoing and several new drugs are in
the process of being developed. The condition is also treated with
cocktails of drugs, the idea being that virus particles that evolve
resistance to one drug will be wiped out by one of the others, so that
resistance will be unable to become established in the population.
It's a technique that isn't foolproof but it does show that our
attempts to combat disease are reliant on knowing how evolution
proceeds.

Philip Bowles