Kodiac Bears and Polar Bears

Evolution (why do you keep calling it “Darwinism”?) can explain a lot of different outcomes, that’s true. These outcomes are the result of different circumstances, which obviously exist in nature. These aren’t all “just-so stories” - we tend to like to test our hypotheses. We might say “I hypothesise that this group evolved this trait for X reason”, and then go out and try and test it. For example, if we observe a cave-dwelling creature without eyes, we can test whether this was the result of lack of selection for eyes or active selection against eyes. If we observe a cave-dwelling creature with eyes, we can test to see if those eyes are serving a subtle function that causes them to be selected for - we can look at genes involved with the developmental pathways that produces the eyes and see if they appear to still be under selection or not. But, sometimes the hypotheses can be hard to directly test, so sometimes we have to settle for “that seems plausible but we don’t really know”.

The ability to explain different observations is not a bad thing in and of itself, it comes down to the evidence for, the plausibility of, those explanations.

Sorry, but in what universe are Kodiak bears and Polar bears "living in the same wintery environment?

Google image search results for “Kodiak bear alaska”:

Google image search results for “polar bear”:

Notice anything different? About the background perhaps?

That’s a good example. Do you know why it’s possibly to work things out after they happened? Because there’s so much more data available! The more economists learn about the way the global economy functions, the better they can understand it, and in some cases they can see things coming (e.g. how some people saw the 2008 financial crisis coming).

Surely you realise that those are fundamentally different kinds of “predictions” that you’re requiring the biologist and the chemist to make. Predicting the properties of a hypothetical molecule is child’s play compared to trying to predict the state of an ecosystem decades or centuries from now. This largely comes down to exactly how much we know about chemistry versus biology, and especially about the particular scenarios. This isn’t really an “evolution” thing, it’s a “biology” thing. Biology is messy. Life is messy.

In order to predict whether the rabbit would drive the existing mammals from their niche and to extinction we’d need to know much more about the specific small mammals in question, as well as the rabbit. With a few years of study it might be possible to ascertain the fitness of the rabbits in that environment, relative to the other small mammals. It would be possible to work out the available food sources, habitable areas, etc. We’d have to study the larger predators and pathogens present in the environment to see how they might interact with the invasive rabbit species compared to the existing populations of small mammals. Only with all of this kind of information could we begin to feel comfortable making predictions about the state of the ecosystem in the future.

You say “natural selection has always avoided that challenge”, and your hypothetical is also mostly about that. Are you saying you’re skeptical that natural selection actually works?

There’s a lot more to scientific predictions than questions like “what will X be like in the future?” More often, they’re along the lines of “if we run X experiment, we’ll get Y result”, or “if we collect X dataset, we’ll see trend Y”. The theory of evolution is capable of making plenty of such predictions, and has lots of nice examples of confirmed ones, which you must be aware of.


You think it never snows in Alaska?

Have a look at these pictures of the Kodiak islands:


You’ll see some bears and bear tracks there.

Of course I don’t think that, why even bother asking? The point is that Kodiak bears and polar bears do not live in identical environments. Kodiak bears live in a much more forested environment that polar bears do, and contend with much greater seasonal variation. In summer there isn’t any snow so white fur would be useless, and in winter when there is snow there is still dark patches of forest for them to blend into. On the other hand, polar bears basically live in snowy environments all year round.

Why not use the term “selectionist” then? You know how much baggage the term “Darwinism” has.

When dealing with gross anatomical structures like eyes it’s almost inconceivable that selection wouldn’t play at least some role. It costs energy to make the eyes in the first place, and they are a body part more vulnerable to injury and infection. If the eyes no longer have a functional role, then if a random mutation happens to, say, break the developmental pathway that produces the eyes in the first place, that will probably have a positive effect on that organism’s fitness. One way to falsify this hypothesis would be to show that eyes either cost an insignificant amount of energy to produce, or aren’t significantly more prone to injury or infection. We already know that’s not the case. Do you have evidence that would lead us to believe that natural selection played no role in the spread of the “eyeless” trait? I’m all ears (or should that be eyes…?).

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@Eddie this seems transparently obvious. What exactly are you disputing?

That is a good suggestion too. Call it “selectionist” rather than “Darwinism”. Or even consider “pan-adaptionalist”.

@eddie, he is right. Do you understand why?

OK, your point about the bears is reasonable, so I will cede the bear example to you; I don’t need it, because there are so many thousands of others. But it wasn’t quite cricket for you to present only pictures of Kodiak Island without snow! Cherry-picking the data, it’s usually called.

Because in classical Darwinian theory natural selection is the most important single cause of evolutionary change. It’s what serves as the designer-substitute, which brings about, as Richard Dawkins puts it, the appearance of design when there really isn’t any. (See the opening of The Blind Watchmaker.)

If “Darwinism” bothers you, then substitute “classical Darwinian theory.” But if you look through Gould’s Structure of Evolutionary Theory, you will see “Darwinism” and “Darwinian” used countless times, as if Gould thought the terms were not a problem.

“Probably”: indicating speculative, a priori reasoning.

Hard to quantify such things, and hard to show the organism doesn’t have the energy to spare.

I never said it didn’t. It might well have. My point was not that selectionist explanations are never correct or plausible. My point was that they cover too much ground, are too flexible – which was Dan Eastwood’s complaint against the idea of a designer (that it was too flexible, too facile at explaining any possible outcome, and hence hard to falsify or test in any rigorous way). And I’m not alone in this judgment. Both Stephen Jay Gould and Richard Lewontin, both of whom presumably knew a thing or two about evolution, offered the same critique of the selectionist “just so stories” often presented to explain why this or that feature is present or not present in a particular organism.

As I said, I literally just did a google image search for “Kodiak bear Alaska” and took a screenshot of the top page of results. I didn’t cherry pick anything.

Gould wasn’t talking in the context of creation vs evolution, where the term “Darwinism” is often used as a slur to imply that modern scientists hold up Darwin’s work as divine truth.

It’s amenable to testing. I actually added the “probably” in there to cover all the bases, as it’s possible that some mutations that disrupt the “eye-forming” developmental pathway could disrupt other aspects of development, incurring a net negative fitness cost.

Hard, not impossible.

The difference is that these “just-so-stories” aren’t presented as hard facts. As I said earlier, sometimes we have to settle for saying “this is a plausible explanation, but we don’t really know”. The explanations we’re more confident in have more supporting evidence, as with anything.

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Also I have critiqued these just so stories. So you are making our case for us. Mainstream science is not selectionist or Darwinist. So why say it is?

No, they aren’t fundamentally different kinds of prediction at all. They are exactly the same kind of prediction. If you know all the causes operative in something, then in principle you can predict its future states.

I agree with you that the situation is much more complex for an ecosystem than for a molecule. But that doesn’t affect my point at all. It merely means that evolutionary theorists have much more work to do than chemists before they can predict future outcomes. But if their ambition is to produce a science, rather than a quasi-philosophical kind of storytelling, their goal should be to refine their understanding of genes, cells, ecosystems, etc. to the point where they can make such predictions.

Both meteorology and economics used to be in the state evolutionary biology is now, regarding prediction of future outcomes. Both sciences, like evolutionary theory, involve very complex systems which are very tricky to model. Yet both meteorology and economics are now far better than they were 100 years ago at predicting future outcomes. They are so good that policymakers often rely on their judgments. So the thing can be done.

@Eddie, there are questions we can ask chemists (more similar to the one you asked the biologist) that they can’t answer either, and never will be able to do so. You are making a false analogy.

That phrase is vague, much vaguer in contents than “Darwinism.” Do you mean, mainstream evolutionary theory?

And supposing that is what you mean, are you aware that I have been chastised here by biologists (or people speaking in the name of biology) for not acknowledging how central natural selection is to the contemporary theory of evolution?

I prefer to avoid labels like “mainstream science” or “mainstream biology” or “mainstream anything”. I would rather people talked about the individual theories of evolutionary mechanism proposed by individual evolutionary theorists, itemizing the similarities and differences between the various accounts. That would be more helpful in promoting understanding than alluding to some undefined “mainstream” and classifying various ideas about evolution as good or worthless depending on how close they are to the “mainstream”.

I don’t think so. It may be that chemists will not be able to answer all questions. But their goal is to come ever closer to complete understanding of chemical causality and hence to complete prediction. Whether they achieve that goal is another matter, but it gives them hope as they pursue their science. My objection to evolutionary theorizing is not that it hasn’t got as as far as chemistry or physics (that’s OK, because the subject-matter is complex, and I’m not blaming the biologists for that), but that many people who argue about evolution in public seem to be happy if the only kind of predictions they ever will be able to make is “after the fact” predictions, Monday morning quarterbacking, so to speak. And the public is never going to be as impressed by a science which can do only that, as by a science which can predict future events. The public is never going to buy the line that the conclusions of current evolutionary theorists about how evolution works are “as certain as the law of gravity” or the like. The public sees that, despite the complexity of the required calculations, NASA can land a craft on a moving target (Mars) from a moving base (Earth), within a few minutes of the projected time, and within maybe 50 yards of the projected landing point. They don’t believe that evolutionary theorists have anywhere near as good a “handle” on exactly how evolution works as the NASA scientists do on how planetary motion and gravity work. The conclusions – regarding mechanism, anyway – are regarded by the public as tentative and debatable, in a way that the conclusions of NASA engineers are not. This could change, of course, if suddenly all evolutionary biologists were in complete accord regarding evolutionary mechanism – but that’s contrafactual at the moment.

I’ve been sternly admonished by several purported research scientists that it’s the duty of a scientist not merely to find evidence for his hypothesis, but to go out of his way to find evidence that would contradict his hypothesis. I’d say you didn’t exactly go out of your way to determine whether there were any pictures of the Kodiak Islands showing snow. :slight_smile:

Nonetheless, I give you your point – the Kodiak bear’s environment isn’t consistently snowy. So I withdraw that example.

Fair enough, but it’s certainly interesting to note that “just so stories” of this kind play a much smaller role in defending theories in physics in chemistry than they do in defending selectionist theory. I think that has a great deal to do with the public perception that physics and chemistry are “hard” science, whereas evolutionary theory, or much of it, is “soft” science, involving more conjecture, speculation, plausible explanation, etc. than is generally thought desirable in rigorous science.

The lack of curiosity is jaw dropping.

Joshua, I should have included a quotation to make sure you knew what I was responding to. You misunderstood what “I don’t think so” on my part referred to.

I was responding to:

Not to:

“There are questions we can ask chemists”.

My point was that using physics and chemistry we can very often predict future outcomes with high accuracy, whereas with evolutionary theory, at least in its current state of development, we cannot. I don’t think this is incorrect, and I don’t even think it’s news.

I granted that chemists can’t predict everything about the future. But they can predict a heck of a lot more about the future than professors of evolutionary biology can.

They are linked. The questions you can ask chemists demonstrate you are making a false analogy.

That chemists can’t predict everything we might ask them to predict doesn’t mean they can’t predict some things, so your point has no effect on my argument.

The fact is that no evolutionary theorist today can make the kind of predictions I was talking about. And the fact is that chemists and physicists can make many such predictions. Even meteorologists and economists can. You can bob and weave, but you can’t escape this point, since it’s straight fact.

If you want to argue that it’s unreasonable to expect evolutionary theorists to make such predictions, then you can do so. If you want to argue that science doesn’t have to be predictive in that sense in order to be good science, then you can do so. But please don’t argue against the facts. Chemistry and physics are much better at predicting future events than evolutionary theory is. So my “analogy”, as you call it, holds, since that is all it was trying to state.

I think you’re labouring under the misunderstanding that when we refer to the ability of scientific theories to make “predictions”, we’re talking about literally predicting future events. That’s not always the case. As I said in my first reply to you, these predictions can include predicting a particular trend in data once it’s been collected. For example, the classic example that gets brought up a lot is the prediction of finding a fossil intermediate between sarcopt fish and primitive tetrapods in a particular rock layer in Arctic Canada, and indeed this fossil was found - Tiktaalik. This was not a prediction of future events, if anything it was the opposite - a prediction of what was present in the past - but a prediction nonetheless.


That biologists can’t predict “everything” we might ask them to predict doesn’t mean they can’t predict some things, so your point has no effect on my argument.


I fully understand the sense in which you are using “prediction”, and I indicated that I recognized this sense earlier. That does not take away from the fact that evolutionary theory, at present, does not have a firm enough grasp of causality to make predictions about future events. That was the only point I was making.

That does not take away from the fact that chemical theory, at present, does not have a firm enough grasp of causality to make predictions about future events. That was the only point I was making.

Shall we go on?