Re: [asa] historical versus experimental sciences

From: David Campbell <>
Date: Tue Aug 11 2009 - 13:39:53 EDT

> "We can be confident, based on evolution, that primates are the best place
> to look for something chemically as well as physically similar to us".
> We could be equally confident without evolution.  Aristotle and Linnaeus
> were both capable of seeing that primates and man had a lot in common.

Linnaeus wasn't committed to the fixity of species. Anyone can see
that man and primates have a lot in common, but there's nothing a
priori outside of evolution that says they ought to be chemically
similar as well.

> In other words, if two organisms are a lot alike morphologically, they are
> probably close evolutionary relatives.  And from that we can deduce that
> they will be alike in other ways as well.  But we hardly need the middle
> step (about being evolutionary relatives) to infer that tigers and lions,
> moose and elk, oranges and tangerines will probably be alike in ways other
> than their shape.

No, similarity in shape only tells us that they probably have
similarities in aspects related to their shape. Oranges and tennis
balls are rather similar in shape but differ substantially in
chemistry, texture, etc.

> Regarding the liver example, I prefaced it by "if (let's say)".  Given the
> premise, the logic was impeccable.  If the premise was faulty, then delete
> the example; I could come up with thousands more.  And the point was equally
> made in my example of the broken bone, which apparently is not objectionable
> to you.  So if you understand the point, why quibble over one of two
> examples?

Problems with the other example were already pointed out. (Another
problem with it is the fact that knowing what caused the accident that
led to the broken bone would be useful in trying to prevent similar
accidents.). The logic of inference from the example to the dismissal
of evolution is faulty. Of course, if you circumscribe a problem to
specifically deal with one particular practical issue, and take all
relevant inferences from general principles as given, you don't need
to refer back to the general principles that led to the relevant
inferences. But that does not prove the irrelevance of the general
principles. A baseball player trying to hit a ball does not have to
consider atomic theory, or even to know the laws of motion, but those
underlie what he is doing. If he wants to hit the ball harder, he can
experiment and find an empirical approach, or he can save time by
doing the physics and determining how to maximize the energy
transferred to the ball.

> The point is that medical applications of biology proceed from empirical knowledge of how the creature's organs and systems work.  That is, they proceed from physiology, anatomy, developmental biology, genetics, etc.  If we know that gene number X5B97 (I'm making that up, because I don't know the labelling system for identifying individual genes) causes such and such a kind of cancer, then whether that gene evolved in the Mesozoic or the Cenozoic, whether it was originally transferred to human beings by a virus, or whatever, is all irrelevant.  Wherever it came from, it's now a permanent fixture in the patient's genome, and it's killing the patient, and either we can treat the cancer or we cannot.  If we cannot, the patient dies.  If we can, the patient may live.  And no physician is going to phone up Allen Orr or Jerry Coyne or Richard Dawkins in order to get evolutionary advice on how to treat the cancer, if it's treatable.  They're going to read up on it in specialized !
 texts in physiology, biochemistry, oncology, etc., written by people who actually know something about the day-to-day functioning of human bodies.  They will save the patient, if they do, by thinking like engineers or auto mechanics, not by thinking like evolutionary theorists.<

But to know what the gene does and how it's supposed to work,
evolutionary data may be quite handy. In turn, this will help tell us
how to deal with the underlying genetic problem. Of course, the first
task is stopping the cancer, which depends on medical knowledge
(although discovering a cancer drug in species X should prompt study
of its close relatives to see if there are related useful compounds).
 Cancer itself is something of an evolutionary situation, in which the
cancerous cells are evolving ways to dodge the body's controls while
the body tries to respond. Remembering that the cancer (or any
pathogen or parasite) is continually evolving is an important part of
maintaining medically relevant treatments. Cf. the Doonesbury cartoon
where the doctor asks the creationist patient whether he wants the
original drug or the ones that are effective against the strains that
have evolved resistance to the first drug.

In trying to prevent recurrence, we need to know what the flawed gene
is supposed to do. Just suppressing the gene and seeing what the
effect is on the patient is not a good idea. Rather, we can look at
related organisms to figure out what the function of the gene is,
where it came from, etc. This will help us know how to target the
negative effects of the gene without compromising any useful function.

Another good example of medically relevant evolutionary information
comes from Toxoplasma (a protist parasite usually caught from cats,
can cause severe problems for developing babies but otherwise not much
obvious impact on humans). It turns out to be more closely related to
plants than to animals, which may help in developing drugs that will
target it but not affect us (or cats).

Another area where evolutionary data are very relevant is in
conservation. What's the best common model species to study or
experiment on for comparison with a rare species? Is this population
all that different or not? What populations are safe to mix for
captive breeding? For example, the dusky seaside sparrow was a rare
subspecies in Florida. The last few males were captured and breeding
was attempted with a similar-looking subspecies, but not successfully.
 Molecular studies later showed that despite similar feather colors,
the chosen other subspecies was not very closely related to the dusky
and was not a good choice.

Yet another area is in the use of evolutionary algorithms or in vitro
evolution to develop some end result/product of practical interest.

> I'm sorry, David, but your case for the practical uses of evolutionary
> theory is weak.  Nothing you've said in multiple posts convinces me that a
> Ph.D. in evolutionary biology has any advantage, when it comes to practical
> applications, over an intelligent generalist with empirical biological
> knowledge and plain old common sense.

It depends very much on the definition of "practical applications."
Furthermore, this does not disprove practicality of evolutionary
knowledge. Does a PhD in evolutionary biology have an advantage over
someone with the same background except for the evolutionary
knowledge? Empirical biological knowledge, or any other empirical
knowledge, is quite useful, but having theory to guide generalization
of that knowledge is also useful. My grandfather worked for
Westinghouse and generally had a low opinion of the merits of the
engineers unless they actually talked with the people doing the
factory work to get empirical feedback. Nevertheless, their
engineering training was not devoid of use.

> I myself would have tried a morphologically similar fruit fly in the search for the right pheromone to
> save the crops, and evolutionary theory would never have entered my head.

Unfortunately for this approach, there are a whole lot of fruit flies
that look a lot alike, and some that look really weird that are more
closely related to some ordinary-looking ones than many pairs of
ordinary looking ones. It turns out that the standard lab Drosophilia
is not as closely related to the actualy type of Drosophilia as are
all the weird Hawaiian ones, for example.

> And I've already said that I don't think evolutionary biology needs
> practical applications to justify itself, any more than Newton needed to
> send up a satellite in 1695 to justify his theory of celestial mechanics. My
> point is merely that nobody expects evolutionary theory to be practical, any
> more than they expect the Big Bang theory to be practical, so Darwinians are
> wasting their breath trying to sell it to the public on that basis.

A claim of practical relevance is, of course, a valuable selling point
and so it is likely to be overemphasized. On the other hand, tying
something into practical applications helps someone see that it is of
relevance, and so it is a legitimate pedagogical tool.

> They have to try to sell it to the public on the basis that it is true, i.e., that it accurately describes what happened in the past upon this planet.  And the way to do that is to *provide the detailed, stepwise, genetic mechanisms which can explain the origin of major organs and systems and body plans*.<

That's one way, though certainly not the only way. As pointed out
previously, this is at best beyond present technology and quite
probably humanly impossible to give in every detail with 100%
certainty. However, what we do have are lots of data from
paleontology, comparative biology, genetics, molecular biology,
biogeography, etc. that match what is expected from evolutionary

>  Until they can do this, they have only themselves to blame for the fact that half of the American public finds the theory incredible.<

No, there's also all the people who claim that it promotes atheism,
excuses immorality, or otherwise misuse evolution to promote social
and moral agendas; the people who make bogus claims to debunk
evolution; poor presentation of evolution in textbooks and classes
(better fact checking would generally make textbooks worth a little
closer to the exorbiant prices charged!) and the many factors that
contribute to a generally poor grasp of science among the general
public such as the cultural promotion of making up one's own "truth";
various industries attacking science because it can cut into their
profits by highlighting the dangers of their products, pollution, or
practices; laziness; public school teaching emphasis on politically
correct (whatever the relevant bureaucracy perceives as deirable, not
only the current U.S. political left's correctness) agendas rather
than on learning information, etc.

Dr. David Campbell
425 Scientific Collections
University of Alabama
"I think of my happy condition, surrounded by acres of clams"
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Received on Tue Aug 11 13:41:02 2009

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