The Talk.Origins Archive: Exploring the Creation/Evolution Controversy

Testing Scientific Theories
From the thread "SILL NO EVIDENCE to back up Evolution of Man" [sic]

Post of the Month: November 2001
by Chris Ho-Stuart

Subject:    Re: SILL NO EVIDENCE to back up Evolution of Man
Date:       November 19, 2001
Author:     Chris Ho-Stuart

In sds <> wrote:
>> Principles of gravity can be expressed in simple one line equations
>> like f = GmM/r^2; whereas evolution is not expressed in any such simple
>> form. This has nothing to do with levels of certainty.
> Makes it easier to test gravity than evolution, thus I maintain it is more
> certain.

I disagree that ease of testing corresponds to increased certainty.

However, what makes this thread difficult is that I am unsure precisely what propositions you are contrasting. "Gravity" and "evolution" are not propositions, but names for phenomena which most certainly exist, and for which we a good understanding of some aspects and poor understanding of others.

That there is a force between two masses, and that living creatures evolve, are both certain. Asking which is more certain is rather like asking if it is more certain that the USA exists, or that Chinese are human. It is a silly comparison, and I honestly have no idea why or how one would try to quantify or contrast levels of certainty about such things.

That humans and apes are related, and that the Earth and the Sun are gravitationally attracted to each other, are both certain. The only basis for considering some kind of "level of uncertainty" in either case might be...

a) a kind of philosophical position in which one is also uncertain that World War 2 really happened, or whether I really exist or am just a brain in vat being fed simulated experience by maverick researchers, and so on. Quantifying this kind of uncertainty is pretty meaningless.

b) a genuine personal uncertainty about evolution, which is quite common, primarily due to religious opposition and poor knowledge of the available facts and data. This kind of personal uncertainty is common, but subjective, and does not reflect any kind of useful scientific insight.

>> What you may be missing is that this simple equation for gravity is
>> actually wrong. Einstein made a better stab at it with general
>> relativity, which is a bit more complex; and gives more accurate
>> results.
> I know this very well. So you agree that not only do we know that
> f=about GmM/r^2, but we also have an idea just how much error there is
> in this simplified representation. That's much more than can be said
> about evolution (ape-to-man).

Above, we seem again to have an implicit assumption that a model which is simply quantified is thereby more certain. Yet elsewhere we had apparently agreed this was not so.

Evolution is not simply quantified with an equation (though there certainly are mathematical models for many aspects of evolution) but we have already agreed that this is not relevant for deciding "how certain" one might be.

Quantifying errors in the gravitational model which is known to be incorrect is not a measure of certainty; it is a measure of the accuracy of a model known (with 100% certainty) to be a "wrong" but sometimes useful approximation.

Ape to man is not a quantified statement; and there is no error to be measured anyway. It is certain; just like it is certain that the Earth and Sun are gravitationally attracted to each other. Both are certain; and being able to quantify some aspect of these phenomena has nothing at all to do with how certain we are of the basic fact of evolutionary relationship and of gravitational attraction.

We can also find some aspect of this evolutionary model to quantify; let me reflect on that as a better comparison with a quantification of the gravitational force. We could measure the time to the most recent common ancestor of humans and apes.

At this point, a brief aside. I will not use the term "ape to man", as it is rather misleading. We are bipedal apes; making a sharp distinction between humans and all other apes is rather artificial, and reflects our obvious and reasonable special interest in ourselves.

The relationships between many apes species is as shown here. (Read with a monospace font).

                   /  \
                  /    \
                 /      \           (There is no sensible vertical
                /        \           scale. It was simply chosen to
               /          \          fit the labels at the bottom.
              /            \         Lucy is from a now extinct species
             /              \        Australopithicus afarensis; but
            /\               \       that did not fit on my diagram.
           /  \               \      Tree shows relationships only, and
          /    \               \     omits many species. There is only
         /      \               \    on human species living at present.
        /\       \               \   This has not always been the case,
       /  \       \              /\  unless of course true by defining
      /    \       \            /  \ "human" to exclude any other now
     /     /\       \          /    \extinct species.)
    /\  Lucy \      /\        /      \     
   /  \       \    /  \      /        \     
  chimps   humans gorillas orangutan gibbons
Something which *can* be quantified is the time to the most recent common ancestor. Note that we have different common ancestors with different ape species. Of most interest is the time to our most recent common ancestor with the chimpanzees. This is roughly 5 million years. That number is (by comparison with measures of gravitational attraction) highly imprecise. Evolution does not have a simple mathematical formula for defining times to most recent common ancestor, and this has nothing whatsoever to do with it being any more or less certain.

There are some other interesting aspects of the tree which can be used to illustrate things which are not certain. For example; are we more closely related to chimps, or to gorillas, or are chimps and gorillas more closely related to each other than to humans? Three possibilities. This question has been all but resolved by the genetic data. Chimps and humans are most closely related to each other, and then to gorillas. There might be some residual question on the matter, but it is now 99.9% certain; and with more sequencing of the chimp and gorilla genomes, the matter will become one in which dispute over certainty reduces to a kind of philosophical uncertainty about everything, which is not relevant to science or a useful measure of certainty in real life.

GmM/r^2 is certainly incorrect. We can quantify how accurate it is (under certain circumstances) in which other more accurate relativistic theories apply, and in still other circumstances, we have no theory that works at all at present, and no sensible notion of measuring "how accurate" this approximate model is, because at Planck levels the defects are not in accuracy so much as in the notions of space and time implicit in the use of classical equations.

>> Evolution (e.g. ape-to-man) does in fact have backing quite as solid
>> as the backing for the existence of gravitational forces.
> There is just no way you can mean that. Little old me can
> directly demonstrate gravity quite easily, but there's no way
> to directly demonstrate ape-to-man evolution. If you could,
> you'd be famous the world over!

I most certainly do mean that, and the various people who have already directly demonstrated the close relationship of apes and humans by various means are famous the world over already. The paleoanthropologists like the Leakeys who have found many transitionals which defy simple classification into "ape" and "human" are the most famous in popular culture; and the geneticists and microbiologists who have resolved questions concerning which apes are most closely related to which other apes (humans included) are also famous but perhaps mainly in scientific circles.

None of this is Nobel prize stuff. The relationship has been known since the time of Darwin and before (though lack of a mechanism made skepticism a more reasonable position in the nineteenth century). The steady accumulation of data throughout the twentieth century has illuminated the relationship, and this data is mainly useful not for confirmation of the obvious fact of relationship; it is for spelling out the details.

>> Comparing "levels of certainty" is not useful.
> It is to me! I want to know how sure the scientific community is
> of something before I decide to bite off on some proposed concept.

Ok. They are 100% certain. Really.

The only basis for uncertainty about the relationship of apes and humans is either sterile philosophical uncertainty about *everything* (which is of little immediate concern to the scientific community) or a religious insistence on treating the bible as a scientific alternative, or a lack of knowledge of the details.

With respect to the scientific community, the relationship of apes and humans, and our shared ancestry, is as certain as anything can possibly get in science.

>> Of course gravity exists. Of
>> course we are related to apes. That gravity can be (approximately)
>> expressed as a simple one line equation does not make it more
>> certain.
> But the fact that it just so happens to be easily demonstrated does.
> Large-scale evolution would take eons to directly demonstrate.

I think we continue to run aground on the idea that "direct" observation is somehow "more certain" than "indirect" observation of effects or consequences. This may be a useful distinction in the popular view, and it can be very useful for education or persuasion outside of science; but within the mainstream scientific community the distinction is a bit suspect, and it does not correspond to "more certainty".

We have never observed a complete orbit of Pluto: but we have observed parts of its trajectory, though only indirectly through very sensitive instruments. That Pluto orbits the Sun is, however, no less certain than the orbit of a satellite around the Earth. That one is "directly" observed has nothing whatever to do with making it "more certain".

Let me try and make the point another way. The Grants conducted a twenty year detailed observation of finches in the Galapagos islands. They observed and documented and measured evolution in action over that time; very high rates of evolutionary change. Nothing comparable in the way of continuous careful direct observation of evolution had been done previously. And yet... this did not make evolutionary change any more certain. Evolution was already certain. Scientifically, the significance of their work was for its insight into the details of known phenomena.

>> The interesting questions are in the bits which are not
>> certain. How gravity works at Planck scales. How the various
>> australopithecines fit into our ancestry. These are uncertain, to
>> be sure; but the kinds of uncertainty to which you seem to be
>> referring are something different; as if there was a useful notion
>> of contrasting how certain we are that there are gravitational
>> forces with how certain we are that humans and apes are related.
>> One might as well compare how certain we are that the USA exists,
>> with how certain we are that Chinese are really humans.
> Both of your examples (the last two) are know with essentially 100%
> certainty. The existence of gravitational forces are known with
> essentially 100% certainty. Large-scale evolution is known with
> something less - say 99.99%, but that's still quite a different
> category and should always be presented as such.

No; it also is 100% certain. This is a real point of disagreement; and the various reasons you have advanced for asserting this distinction are not persuasive. You speak of "direct observation", and of "measured errors", but neither of these imply increased certainty in science, in the way you suggest.

>> >> Not only is there a theory of evolution, but it has been
>> >> confirmed by all of the observations to date.
>> >
>> > Why make such false statements - it's unnecessary. There
>> > are many observations that are highly controversial as to
>> > whether they do or do not support the theory of evolution.
>> > For example, in experiments involving over 3000 consecutive
>> > generations of fruit flies, no increase in complexity or
>> > viability was ever observed. This observation certainly
>> > doesn't support the theory of evolution. Even in the face
>> > of efforts to increase mutation rates, no clear genetic
>> > improvement has ever been observed in any form of life.
>> > We must be alarmed by this if we subscribe to this theory.
>> This is simply wrong.
> I assume you mean my conclusions are wrong, not the facts stated.

No; I mean some of the facts stated are not facts; they are incorrect; and also that the implicit assumptions are incorrect.

Let me walk through the above paragraph, to give my perspective.

>> > There
>> > are many observations that are highly controversial as to
>> > whether they do or do not support the theory of evolution.
>> > For example, in experiments involving over 3000 consecutive
>> > generations of fruit flies,

The experiments on fruit flies are not controversial as to whether or not they support evolution. There is the usual sterile "controversy" outside of the scientific arena as to whether demonstration of evolutionary change has anything to do with "macro-evolution" or some such; but I presume we are here speaking of the scientific community. Here there is no particular "controversy" associated with the fruit fly research. It does demonstrate and confirm and illuminate many aspects of evolution.

>> > no increase in complexity or
>> > viability was ever observed.

Here is an implicit assumption that evolutionists should expect an increase in "complexity" or "viability". But since fruit flies are already well adapted to their environment, we do not expect to discover a kind of generic increase in viability. That appears to be founded on a common misperception of evolution as a ladder of continuous progress against some absolute standard.

What has been observed and measured is adaption to artificial changes in environment; and this corresponds better to real evolutionary expectations.

The term "complexity" is a give away. This is not something evolutionists measure; it is something which critics of evolution invoke without ever defining clearly. It is also founded on a misperception of evolution as ladder of continuous progression.

>> > This observation certainly
>> > doesn't support the theory of evolution.

The real observations made certainly do support the theory of evolution.

>> > Even in the face
>> > of efforts to increase mutation rates, no clear genetic
>> > improvement has ever been observed in any form of life.

This is simply false. The archives document a number of unambiguously beneficial mutations. But again, evolution is not about a kind of continuous "genetic improvement". It is about genetic change, and consequent phenotype change, and about selection of variations based on immediate local environments.

The observations of finches to which I have alluded above plainly show (as expected; but the rates involved were surprising) that evolutionary change is not continuous improvement by any objective measure, but chaotic change that tracks a local environment to change first in one way, and then back again in another.

>> First of all, we don't expect to be able to form "better" or "more
>> complex" fruit flies over 3000 generations.
> Yes we (some of us) did - that's why we performed the experiments.
> We thought that was one possible outcome. That is the key to
> the overall theory of evolution. Better adapted (as far as
> proliferation goes) offspring prevail.

That expectation would be an error, and it is incorrect that such expectations were the reason for the experiments or were part of the expectations of the scientists involved. What was expected was that we might be able to form slightly "different" fruit flies by altering local environments in which they lived. (It was not expected that we could make "better" fruit flies by any generic measure, and most certainly not "more complex" -- an undefined notion of no particular interest to the scientists involved, precisely because it so meaningless.)

>> Fruit flies have had
>> far more generations than this to become adapted to their present
>> niche.
> But we were looking for even the slightest detectable change and found none
> of the sorts needed to support large-scale evolution.

There were indeed plainly detectable changes, and the changes found were indeed of the sort which were as expected for the changes that can accumulate to give large scale evolution.

>> To test real evolutionary theory, rather than a straw man,
>> one tries to change the niche in which the flies exist, and see if
>> they can become better adapted to a new niche, or show signs of
>> divergence when subjected to artificially distinct environmental
>> conditions. And this *is* observed, as expected, and observations do
>> in fact support evolutionary theory, and allow its further refinement.
> You are wrong here. These results simply demonstrate what everyone
> on both sides of this issue agrees on - natural selection and genetic
> variability. Any knowledgeable antievolutionist would expect precisely
> the results that have been observed. I said you are wrong - I mean only
> if you claim the results supported large-scale evolutionary theory.

What, precisely, do you think is wrong? My description of what fruit fly experiments are attempting? My claim that signs of adaptation and divergence are directly observed? My claim that observations made support evolutionary theory? My claim that observations have allowed refinement of evolutionary theory?

Or are you objecting because you insist that only a "direct" observation of "large-scale" change (by which you apparently mean change sufficiently large that evolutionary theory would expect it to take millions of years) can be a support of evolutionary theory or allow its further refinement?

I have tried to spell out where you are wrong above; perhaps if you can do the same for me it might help.

And here is an analogy...

The galaxy is bound together by gravitational forces. This is large scale gravity. It is not directly observed, because we have nothing like the available time to observe even a single rotation of the galaxy or its long term motions. But we do observe localised motions of smaller bodies, and construct a theory which can be applied to the structure of a galaxy. Is there a useful distinction here? Is observation of orbiting bodies a good way to support and refine gravitational theory and does this, or does it not, help explain the longer term motions and structures of our galaxy?

>> You appear to be thinking of evolution as a theory by which life
>> continually ascends into better and better, or more complex and
>> more complex, along some plain sequence. The real problem may
>> simply be (no offense intended) that you don't really know what
>> evolution actually entails.
> No offense taken, but I think I really do understand it pretty well.

Um. OK. In that case, would you perhaps be able to give a definition of "complexity" which makes sense of your statements about fruit fly experiments? Specifically, how would you measure whether or not a change to a fruit fly made it more, or less complex?

I propose to test your definition by seeing if a fruit fly is more, or less, complex than a house fly.

>> >> The problems raised by religious objections to science are generally
>> >> naive and/or out-of-date. The problems that scientists are dealing with
>> >> are far more interesting and far more intractable than the false
>> >> problems raised by religious objectors.
>> >
>> > That's a bit over generalized, but I probably agree to some extent. But
>> > I don't think any credible antievolutionist (no, that's not an oxymoron)
>> > has any objection to science. I do agree there are plenty of incredible
>> > ones that do!
>> Agreed.
> That's the first time anyone of a dozen or more posters has used that word
> in response to me! That's truly amazing, because I know I'm not 100%
> wrong 100% of the time!

I'm an agreeable chap. :-)

Best wishes -- Chris

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