Total Drek

Or, the thoughts of several frustrated intellectuals on Sociology, Gaming, Science, Politics, Science Fiction, Religion, and whatever the hell else strikes their fancy. There is absolutely no reason why you should read this blog. None. Seriously. Go hit your back button. It's up in the upper left-hand corner of your browser... it says "Back." Don't say we didn't warn you.

Tuesday, March 23, 2010

It's reader Q&A time!

Interested reader Kyle left a request/comment on yesterday's post that went as follows:

Show me the missing link then. If evolution isn't fact it takes faith by definition. If it is fact then we would be able to show the missing link between land and airborne animals. And there isn't one. It is impossible for a land animal to evolve into a flying creature because of the difference in lung structure. The lungs would collapse into themselves before coming to a form that could sustain the life of the "inbetween" stage.


Now, there's a lot here, Kyle, so I hope you'll permit me to unpack your comment and respond to it bit by bit. Rest assured, however, that I will do my best to answer your main question- just please do me the courtesy of taking the time to read my response.

Show me the missing link then.


You begin by bringing up the whole "missing link" notion, which is a compelling image but unfortunately reflects a somewhat misguided notion of evolution. The thing to keep in mind about evolution is that it does not argue that at some point a member of one species gives birth to a member of a different species- roughly akin to a fish spontaneously giving birth to an amphibian. Instead, at each generation the offspring resemble the parents about as much as offspring usually resemble parents. Over long stretches of time offspring and parents at one point may differ rather a lot from offspring and parents at another point in time but, nevertheless, there is no sudden, dramatic cleavage between the two. As such, there is no one "missing link," but instead a whole succession of gradual changes leading between two forms. This is all the more critical because the concept of a "species" is- by and large- one made up for our convenience. In nature, two creatures we might consider different sometimes can and do produce fertile offspring. And at some levels (e.g. bacteria) the trading of genetic material between "species" is commonplace. This means that on a literal level responding to your request is impossible because there is not and never will be a missing link- not because evolution is wrong, but because the common conception of it is wrong.

By way of analogy, I'm sure you resemble your father to at least a degree. Likewise, you probably resemble your grandfather to a probably lesser degree, and so on with your great-grandfather, your great-great-grandfather, your great-great-great-grandfather and on until, say, your great^50-grandfather. Odds are that you don't look all that much like your great^50-grandfather despite the relation- there has just been too much time separating him and you, even though at every generation father and son resembled one another. Now imagine that you have an oil painting of your great^50-grandfather and a photo of you and you proudly show them to a friend who responds, "You two look nothing alike! You're pulling one over on me! I need to see the missing link between him and you!" How do you respond? At what generation does the "missing link" occur? When in this chain of gradual change is the pivotal moment? Obviously, there is no such pivotal point- the change is spread out over many, many successive generations. Nevertheless you might find a painting of an intermediate relative, say your great^25-grandfather, and present that. Your friend still may refuse to accept this evidence, however, and point out that now there are two "missing links": one between your great^50-grandfather and your great^25-grandfather, as well as a second "missing link" between your great^25-grandfather and you. You might show your friend the family tree linking all of you- as biologists show us the family tree linking species (more on this later)- but your friend wants something "more real". And so you are left digging through family heirlooms and records trying to find a painting or photo of every one of your male ancestors between you and your great^50-grandfather so that you can close all the "gaps". This is roughly analogous to the situation evolutionary scientists are in- we have the oil paintings and photos for some of the members of a chain. We have the family tree. We even have resemblances between steps that make the sequence pretty unmistakable but, nevertheless, there comes the demand for the "missing link".

So, given all of this, I hope you will forgive me if I respond to your demand in a way other than by pointing at one specific fossil and suggesting- fallaciously- that it is the "missing link".


If evolution isn't fact it takes faith by definition. If it is fact then we would be able to show the missing link between land and airborne animals. And there isn't one.


You're right that if evolution is fact we should be able to show evidence for it- and, in fact, we have. There's gobs of evidence for it. We've demonstrated evolution at the microscopic level both in the lab and in the wild. We've demonstrated evolution at the macroscopic level both in the lab and in the wild. We've even observed evolutionary change in human populations within a historical timeframe, although this change was relatively minor. Added to this is the DNA evidence that demonstrates conclusively that all life on earth is related at a fundamental level. Now this is an important point, so allow me to elaborate: life on earth with few, if any, exceptions uses DNA as its carrier of heritable material. Moreover, this DNA operates in essentially the same way. This is roughly akin to noticing that not only is every book in a library written in the same alphabet, but that the grammar and syntax are always the same. The words, however, change and the degree of difference between those words allows us to see how similar, or different, various species are. And we indeed find that every organism is related to every other one in a logical and coherent manner. This is key because it did not have to be the case. Under creationism, there's no particular reason to expect such an all-encompassing set of links among existing organisms. God could have simply made every creature from scratch, starting over so as to perfect each one for its role. Instead, we see evidence at the morphological and genetic levels that each creature is simply a variation on the last one- exactly what we should see if evolution is correct. You'll note at this point that all of the evidence I've brought up- every last bit- derives from experiments and observations carried out right now. None of it relies on fossils, and that's a critical point: without even looking at the fossil record we can conclude with absolute certainty that evolution can and does occur. This is not in dispute, we've seen it both under controlled conditions and in the wild. We've observed the current DNA similarities between all creatures. We know that evolution is going on around us right now because we have seen it happen. Digging up fossils that show evolution occurring is thus helpful, and sometimes very informative, but is not fundamentally necessary to show evidence for evolution.

Looking at your comment more broadly, you remark on the issue of fact and faith. First off, I wonder if you aren't falling back on the old argument that "evolution is just a theory." This, too, is a misconception of sorts, because in science a "theory" is not a wild, unsupported guess. A theory is, instead, a logically rigorous set of explanations that has been vindicated by repeated testing. Other prominent theories include the germ theory of disease, atomic theory, electrical theory, and the theory of gravity. All of these are "just theories" but, nevertheless, your microwave works, you don't fly off the surface of the earth at random, and good sanitation helps prevent disease. Now, it is true that science relies on a degree of faith, but this is different from relying on Faith. The faith that science uses is akin to making limited assumptions and testing those assumptions whenever possible. So, for example, we might assume that radioactive decay occurs at a constant rate and use that assumption to study phenomena, but will still try to test that assumption as often as possible. We can never really be certain that in a moment or two things won't change but, by and large, since they never have before, we have faith that they're not going to suddenly, radically alter. The alternative Faith, on the other hand, refers to certainty in specific things whose existence or role cannot ever be exposed to testing- such as Faith in god. Science, and evolution, does rely on faith, but it eschews Faith, and thus your sketched argument is invalid.


It is impossible for a land animal to evolve into a flying creature because of the difference in lung structure. The lungs would collapse into themselves before coming to a form that could sustain the life of the "inbetween" stage.


And here we come to the crux of the argument: that it is impossible for land animals to becoming flying animals because the lungs would collapse along the way. I was, I admit, somewhat surprised that this was the hook on which you decided to hang your opposition: I've usually seen greater attention paid to the more dramatic change from aguatic to air-breathing animal. But, that said, since the discovery of Tiktaalik, one of those hypothetical "missing links", perhaps it seems less wise to argue in that direction.

You don't provide much detail to your objection, which is a shame because it is demonstrably and trivially incorrect. There are a multitude of flying insects, such as the Dragonfly, which are both animals (i.e. members of the kingdom animalia). This is an important point because insects do not have lungs at all, and yet, they still fly. And so we can see that your objection is without merit, because animals don't need lungs to fly. I suspect that you will not like this argument, however, and will dismiss it because insects are small, seemingly unimportant, and obviously not what you mean. That would be an unwise reaction on your part- if powered flight can be achieved with the simple breathing apparatus used by insects so long as the insect itself is small (and there is evidence that in times past some flying insects were quite large), then there is no reason why powered flight using unbirdlike lungs should be impossible so long as the organism is small enough. Increases in size would, thus, follow changes to the lung structure. And if we quickly search the web we very rapidly (as in "the third hit") find an article that compares modern bird structures to fossils of flying dinosaurs to trace the evolution of lung capacity and animal size. This research finds, as I suggest, that the organism grew in size as the lungs became more efficient.

Still, you're probably referring to an argument like this one that asserts that since the airflow in the avian and reptilian lungs is different one could not have evolved from the other. This sidesteps, of course, the fact that the aquatic to air-breathing shift would seem to have been more difficult, but nevertheless has been supported by transitional fossils as well as extant species that occupy intermediate stages. But, nevertheless, you assert that powered flight is imossible because it can't be supported without specialized lungs. I earlier pointed out that this was wrong because insects do it without lungs. I now maintain your claim is incorrect because bats manage to fly quite dextrously while using standard mammalian lungs. Critically, however, in bats airflow is bidirectional, much as it is in reptiles, and not unidirectional as it is in birds. And so, again, we have a macroscopic and now highly advanced creature capable of agile powered flight that does not have the specialized lungs of birds. And even if you were to respond by saying "Yeah, well, how did birds come to do it with specialized lungs, then?" I would simply respond by pointing out that their predecessor dinosaurs appear to have already had that structure, or something similar, before flight appeared.

So, in short: your basic assertion fails on numerous grounds.

In closing, allow me to encourage you to take the time to actually explore the research on evolution. It is not a faith position but a scientific theory that has received extensive testing. Allow me also to point out that most scientisits, and most people who believe in evolution, also believe in god. Accepting one does not mean rejecting the other. Indeed, if you reject evolution because you believe in god, it seems that you are trying to claim that god could not have done it that way if he had chosen to- which seems just a tad presumptuous for one as devout as yourself. There is overwhelming evidence for evolution and one can only assume that if there is a god, we were expected to put it together.

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8 Comments:

Blogger LemmusLemmus said...

"A theory is, instead, a logically rigorous set of explanations that has been vindicated by repeated testing."

Ahem, ahem. A system of explanations that is wrong - such as one that has not been vindicated by repeated testing - is still a theory.

The mistake in the claim that evolution is "just a theory" is that it isn't just a theory, but instead a theory which has withstood scrutiny. Which is quite a feat to accomplish. Crafting such a theory, I mean.

Tuesday, March 23, 2010 11:38:00 AM  
Blogger Drek said...

Hey LemmusLemmus,

Yeah, I've seen different arguments on this point from different scientists. Some prefer to refer to a set of such explanations that has not been vindicated by testing as "hypotheses", thereby reserving the term "theory" for something more profound. I'm comfortable with your preferred approach, though, and really just went with the more specific definition for clarity's sake. The essential point, on which we both agree, is that evolution isn't just a wild guess precisely because it has been exposed to extensive testing and emerged successfully.

Cool?

Tuesday, March 23, 2010 12:30:00 PM  
Blogger LemmusLemmus said...

Well, I'm not the kind of person to get excited over definitions! It's just that I hadn't heard your more restrictive use of the word before - but then, I'm not even a native speaker of English, so don't put too much weight on it.

As for theory vs. hypothesis, what I've been taught is that an hypothesis is a single claim, while a theory is a system of hypotheses - if you have at least two interconnected claims, you have a theory. (In practice, it may be hard to distinguish where one hypothesis ends and the next one starts.)

And then there is the use of the word "theory", not unpopular in sociology, referring to everything that's not empirical. But that's another matter.

Tuesday, March 23, 2010 1:10:00 PM  
Blogger Drek said...

Well, I don't think it's a native English vs. non-native English issue so much as differing perspectives between various parts of the scientific community. I tend to prefer the definition under which it isn't a theory until it has received substantial verification, but I'm not a stickler for it.

You're right that the term theory is overused (regardless of the choice between the different ways of defining it that we've discussed) in much of sociology. For what it's worth, American sociology is very different from most European sociology (and, I would argue, more scientific in orientation) and there's a solid core of sociologists who are more rigorous in what they call theory. At the same time, we also have a lot of folks who are quite sloppy, which leads to all kinds of frustration.

Tuesday, March 23, 2010 1:46:00 PM  
Blogger LemmusLemmus said...

To switch gears: Isn't it frustrating to write a longish essay in response to a short comment and then not even having the commenter reply?

Wednesday, March 24, 2010 11:27:00 PM  
Blogger Drek said...

Yeah, it's a tad frustrating, but I'm semi-accustomed to it at this point. Really, I write the longish essays less for the commenter- who rarely comes back for fear of learning something- and more for the next person who might stumble over the post and/or comment. I sometimes worry that if I don't respond thoroughly that some later person will smugly get the idea that it was because I can't rather than that I chose not to because the original comment was just so silly.

Thursday, March 25, 2010 6:49:00 AM  
Blogger Jay Livingston said...

I'm not Kyle, but I was impressed by this post -- grateful for it too. Now I don't have to take bio.

Thursday, March 25, 2010 11:01:00 AM  
Blogger mig said...

Sigh, reading this old post is reminding me too well of the current hullabaloo over some Purdue research findings that radioactive decay varies (VERY VERY SLIGHTLY) over time, possibly due to solar neutrino flux:

http://www.purdue.edu/newsroom/research/2010/100830FischbachJenkinsDec.html

But then:

http://whyhomeschool.blogspot.com/2010/09/radioactive-decay-isnt-constant.html

(oooh, fear the themeclones!)

Sunday, September 12, 2010 3:35:00 PM  

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