Monday, March 28, 2011

A question on biological evolution

If doing biology is impossible without assuming biological evolution, as some people (including at least one commenter on this blog) contend, and if it is also true that biological evolution can only be proven by an appeal to biology, then how does the evolutionary biologist avoid assuming what he's trying to prove?

25 comments:

Singring said...

Doing biology is not impossible without assuming avolution - this is a classic misunderstanding. Dobszhansky's famous quote is that 'nothing in biology makes any sense but in the light of evolution.'

Generations of naturalists did biological research before Darwin came along, some of it very valuable and accurate. They didn't need evolution to do basic biology.

Then, because of the weight of the evidence, biology was accepted in the scientific community. It's therefore not an 'assumption' out of the blue like some mathematical axiom or philosophical first principle - it is simply a theory derived from and consistent with the evidence available. A biologists 'assumes' biological evolution the same way a physicist 'assumes' relativity or gravity - all concepts that were not plucked out of thin air, but were the result of the study of emoirical evidence. So your characterization of evolution as an 'assumption' is badly worded or inaccurate at best.

Secondly, you can go out and study population dynamics in salmon or alkaloid production in plants to your heart's content...but when it comes to interpreting your data, it will only make sense if you do it with an eye to the evolutionary context.

For example, I am just writing up a paper from my thesis on the behaviour of parasitic wasps. The wasps appear to incapable of sensing that their hosts are infected with a pathogen and parasitise these hosts anyway. Now as an isolated observation, this might be nice. But to discuss why the wasps may be doing this and what consequences this behaviour has, you must discuss the results in the context of evolution.

Parasitising infected hosts is bad for the wasp's fitness - so why are they doin it? In this case, the pathogen I used is not one that naturally occurs in their habitat. So there would have been no evolutionary pressure for them to develop a mechanism to detect infected hosts.

Biologists don't need evolution to do research. But only in light of evolution do the results make any sense in a broader context.

KyCobb said...

Martin,

Evolutionary biologists aren't trying to "prove" life evolves, evolution has been an established fact, as Gould defined "fact", for over a century. Only creationists are obsessed with that question. As Singring points out, evolution makes sense of the facts biologists learn through research, otherwise, they would just be stamp collecting.

Andrew said...

Singring,

By evolution, do you mean adaptation? If that is what you mean, I'm not sure anybody would deny evolution, but the precise contours of the definition seem to be the area of conflict.

Andrew said...

KYCobb,

Is this what you mean by how Stephen Jay Gould defines facts:

In science "fact" can only mean "confirmed to such a degree that it would be perverse to withhold provisional consent." (From Fact and Theory)

Singring said...

'By evolution, do you mean adaptation? If that is what you mean, I'm not sure anybody would deny evolution, but the precise contours of the definition seem to be the area of conflict.'

For the purpose of discussion, it doesn't really matter how I define evolution. The simple fact is that, contrary to Martin's assertion, biology can and has been conducted without evolutionary concepts being available.

In answer to your question: I have indeed heard a number of different definitions of evolution, with the most basic and broad one being 'the change in the frequency of genetic information in interbreeding populations'.

I suspect that the subtext of your question - similar to what OTF has previously put forth - is that there is some kind of qualitative difference between 'microevolution' (e.g. adaptation) and 'macroevolution' (e.g. speciation). This is of course complete nonsense and the only places where thes terms are in fatc used on a regular basis at all are creationist websites.

But just to pre-empt any furtzher argument on thi issue: If you are looking for people who believe in the most bizarre and crazy rates of adaptation and therefore 'evolution', look no further than to Ken Ham and his ilk.

These are the people who believe that tigers and house cats all managed to somehow 'evolve', speciate and disperse across the globe from one pair of animals (or maybe 7, the Bible is not quite clear on the issue) that walked off an ark in Turkey some 4,000 years ago.

That is radical, extreme evolution at a speed and intensity no sane biologist would ever accept.

But that's the kind of mental acrobatics Creationists have to perform: 'Evolution is false! Except actually its true its just super-duper fast!'

I don't see how one can do anything but hold such people in contempt and heap them with ridicule.

One Brow said...

Martin,

The notion that something is proven by science is a category error. A common saying is "proof is for mathematicians and alcohol". Note that neither mathematics nor alcohol is a science.

Evolutionary biologists do go around tryijng to provide evidence for evolution, for them that question has been answered.

KyCobb said...

Andrew,

Yes.

Andrew said...

Singring,

Thank you for taking the time to answer my question. I am trying to understand these matters with only a very little biology background, so please bear with me. I do think they are important.

I think you might have argued inconsistently, but i'm not sure. First you said that the definition isn't all that important. Then you said that Ken Ham believes in evolution because he believes that cats adapted at a "crazy rate."

I haven't read Ken Ham in a long time, but I'm pretty sure he would argue that you are using a definition for evolution that he would not accept.

Is it not true that he thinks that adaptation can occur within limits and that thus a cat can change over time to something within the same genetic range but no farther? If he denies that that is evolution, then why do you say he believes in evolution?

On another matter, I have no idea what the range of genetic change might be to a creationist or whatever, but I do think a study that explored the possibility of those limits would be fascinating and profitable regardless of the theological implications.

Do you know if one (or maybe hundreds) has been done and if so can you refer me to it?

Thanks again for engaging my question.

Singring said...

'Is it not true that he thinks that adaptation can occur within limits and that thus a cat can change over time to something within the same genetic range but no farther? If he denies that that is evolution, then why do you say he believes in evolution? '

You have argued for a definition of evolution that basically is synonymous with 'adaptation'. I was simply going by your definition. If you think it is a bad definition, then fine. But then why bring it up?

Ken ham beleives in baramins - i.e. 'kinds' of animals. One of these 'kinds' of animals is the 'cat' kind. I quozte from his website (http://www.answersingenesis.org/articles/nab/really-a-flood-and-ark):

'Many other types of animals— cat kind, horse kind, cow kind, etc.—have similarly been naturally and selectively bred to achieve the wonderful variation in species that we have today.[...]God also made it impossible for the basic “kinds” of animals to breed and reproduce with each other. For example, cats and dogs cannot breed to make a new type of creature.'

So clearly, tigers and house cats both 'adapted' from the two (or seven) precursors that were on the arc. If you compare the DNA or even just the phenotype (i.e. how the animals 'look') it is plainly obvious that even giving the most absurdly liberal leeway in terms of mutation rate and generation length, there simply is no way a tiger and a house cat could have 'adapted' from a common ancestor in less than 4,000 years, let alone a few hundred years or even decades (remember, there's historical records of tigers and cats that go back thousands of years!).

If you can make yourself believe that a tiger and a cat can 'adapt' from a common ancestor in 4,000 years or less, but cannot believe that they can do so in millions of years - then I submit you have an extreme case of cognitive dissonance that borders on the insane.

'...but I do think a study that explored the possibility of those limits would be fascinating and profitable regardless of the theological implications.'

There are many, many studies that have investigated this, here is a review of the data, for example:

http://www.genetics.org/cgi/content/full/148/4/1667

Based on what we know about mutation rates, 4,000 years is nowhere near enough time (not even in the same ballpark!) to produce the gentic variety we see in cats, for example.

Martin Cothran said...

Singring,

Generations of naturalists did biological research before Darwin came along, some of it very valuable and accurate. They didn't need evolution to do basic biology.

So you don't need evolution to do basic biology? I suggest you talk to Art, who made that very claim on this blog. That's who I was thinking of when I wrote this post.

Martin Cothran said...

One Brow,

So would it be correct to say that evolution has not been proven?

Singring said...

'So you don't need evolution to do basic biology? I suggest you talk to Art, who made that very claim on this blog. That's who I was thinking of when I wrote this post.'

I'm not here to speak for Art and I'd like to read the quote you are referring to before passing judgement.

But I assume your question has been answered?

Art said...

It would seem as if Martin is as skilled at reading as he is at math.

Let's try to elaborate:

1. Consider two grant proposals - in any field of biology (doesn't matter). One freely draws upon both the fruits of the truth that is evolution (common ancestry, descent with modification), and one dutifully avoids any and all such reference. One of these will be rich, insightful, and promising as far as outcomes. One will be an empty shell, missing opportunities as it dances around the foundational truth of biology. (Of course, in Martin's world, where merit takes a back seat to entitlement, it is the empty shell that is the preferred project.)

2. Pick a biological subject, any subject. Make a list of what we know of the area. Then scratch off every advance that was grounded in the foundational truth of biology (which includes the long-standing justification for the use of simple model systems, that the fact of common ancestry means that things learned in E. coli, S. cerevisiae, D. melanogaster, C. elegans, M. mus, etc., etc. will apply to other living subject matter) and revisit the list. Needless to say, it will be short.

Can one do biology without evolution? Yes, in the same way one can "do" Christianity without the Bible.

Art said...

While we're at it:

If Christianity is impossible without assuming the truth of the Bible, and if the Bible can only be proven true by an appeal to Christianity, then how does the Christian avoid assuming what he's trying to prove?

One Brow said...

Martin Cothran said...
So would it be correct to say that evolution has not been proven?

It is correct, but it would be more correct to say it "can not be" proven. When you say "has not been", their is a connotation that this is a lack on the part of the evidence for evolution, as opposed to a matter of category.

After all, you could just as easily say the germ theory of disease has not been proven. The radioactivity of uranium has not been proven. The atomic theory of matter has not been proven. The existence of gravity has not been proven. All of those statements are just as accurate as saying evolution has not been proven.

Martin Cothran said...

So let's see if we can get a consensus on or or other here:

Is it possible then to, say, learn basic biology well in a biology text that does not address the issue of evolution, since "need evolution to do basic biology"?

Singring said...

'Is it possible then to, say, learn basic biology well in a biology text that does not address the issue of evolution, since "need evolution to do basic biology"?'

By basic biology I mean descriptive biology. You know, what Linnaeus did, what even Aristotle did. If all you want children to learn is the names of things and pretty much nothing else - then sure, you could learn basic biology 'well' from a textbook - a textbook that would be about 20 pages long and read like a phone book.

Seriously, Martin, are you on a seek and destroy mission to burn and explode even the last vestiges of your credibility as an educator?

You could teach kids the names of plants and animals, for example...but then all they would be doing is memorizing words. The nomenclature makes sense only in the context of evolution! You could teach kids that there are broadleaf and conifer tree species - but why and where they exist only makes sense in light of evolution. You could teach kids that humans and rats both have a liver. But that would only make sense if you also taught them the evolutionary history of humans.

I am surprised that someone who just days ago wrote a passionate defense about the study of latin based in part on the premise that it teaches analytical and critical thinking is now advancing the position that all kids really need to learn in science is a word salad - no critical thinking necessary, no analysis desired. But then why should they be learning latin of those skills are not required?

You are not making an ounce of sense Martin. And once again I will say that it comes as no surprise to me at all that the US is doing so poorly in science education if those who think of themselves as the prime educators in the country can honestly advocate the teaching of biology without reference to evolution.

According to you, a biology class would go like this:

'Hey kids. This is a duck! It quacks and it can fly. For your homework, write the word 'duck' ten times. See ya tomorrow!'

You know what I would like to do? I would give the children who you say 'ace' your logic exam an exam on biology. I have a suspicion they wouldn't so well.

Singring said...

P.S.:

Cue the 'Where did I say I advocate the teaching of biology without reference to evolution?!' response by Martin in 5...4...3...2...1.

Andrew said...

KyCobb

Thanks. Are there any other kinds of facts? For example, in common speech, people generally think a fact is an individual, particular bit of information, like, for example, that I typed this post on my keyboard (which I did, and then put this past tense sentence in at the end).

I know that every (or most) individual bit of information has complex elements to it, but considered as a "fact" it is regarded as a particular combination of elements that make it a fact.

It's also generally regarded as something already accomplished and presently existing as a fact. (This may have to do with its etymology, which, as I understand it, comes from the perfect tense of facio - to make. A fact is something "made," at least in an analogical sense).

For example, it is a fact, not a theory, that Washington crossed the Deleware or, more currently, that I woke up this morning.

So, with all that qualifying, my question is, is there another kind of "fact" besides the kind Stephen Jay Gould refers to?

KyCobb said...

Andrew,

Washington crossing the Delaware is a Gouldian fact, due to the amount of evidence to support it. You having typed your post with your keyboard is not a Gouldian fact, since, for all I know, you had a friend type it. "Facts" in a legal sense are different than Gouldian facts, since a legal fact can be established merely by being more probable than not in most civil matters. So the definition of the word "fact" depends on the context.

Andrew said...

KyCobb,

Thanks again. I appreciate your directness and confidence.

If I'm understanding you, there are at least two or maybe three ways to understand fact.

1. The Gouldian way, where we can look at something that happened and say only a "perverse" person would "withhold consent."
2. A legal fact, where a person is screwed if the probability goes against him.

And here's maybe a third fact: one that is true although it may not be subject to public review.

I thought of number three because of your questioning, hypothetically, whether I typed my post. It seems to me that whether or not I typed it is not in any way conditioned by who knows that I typed it. It is, if I typed it, a fact that I typed it.

Do you agree that that makes up a third kind of fact?

Andrew said...

Singring,

I'm sorry not to have responded sooner, but you must be patient with me. I'm trying very hard to understand you because I don't want to argue with you about something only to find out either that we agreed all along or else that we were arguing about two different things. I do love a good argument, though, so don't take this as me not wanting to argue.

Also, I'm not necessarily defending Martin. I find him evasive and playful, so maybe I can team up with you on him later. But first I need to understand the argument.

So here's where I am in all this:

You said that biology only makes sense in the light of evolution. That, obviously, makes evolution pretty important in the field of biology. So, always having loved, but never having been able to study beyond high school biology, I want to make sure I understand what this thing is by which I can understand biology better - or at least, without which I cannot hope to understand biology.

So I asked whether by evolution you meant adaptation.

Your response was that it doesn't matter for the purpose of the discussion what you meant by the term. At first I thought, What?! You can use terms any way you want and I just have to let you mean anything and still have a discussion with you? You sound like an intellectual tyrant or a teacher or something. Then I calmed down and read your post and I think I see what you mean. Is this it:

"There are various meanings given to evolution and within those given meanings it does not matter which I am using for the purposes of this discussion with the evasive Martin."

If so, I agree with you, sort of.

It is easy to see how biology makes such amazing use of the concept of adaptation that it has made breath-taking discoveries over the past century. Darwin and/or Mendel and/or whoever else you know about that I don't gave us a model with which we can think about biological change. And it is a model that is obviously right in a Gouldian sense.

But if I'm going to argue with Ken Ham, or with Martin (who does not hold to Ken Ham's position), then it does seem important to worry about what I called earlier, rather imprecisely, "the contours of the definition." Especially if I am going to go to the trouble of dismissing one or both of them as worthy of contempt and ridicule.

A human being is an extraordinary thing to me, and for one to be worthy of contempt takes a real evacuation of one's dignity.

So what I need to understand is, does the term evolution demand, in all uses, adaptation without limitation.

As I said earlier, I'm sure neither Ken Ham nor Martin Cothran would have any trouble with the concept of evolution if it means adaptation or even, the one you helpfully provided: "the change in the frequency of genetic information in interbreeding populations."

I have no trouble defending or using the concept of evolution with either of those two (which are probably one) definitions, if I understand the second one correctly.

But some people believe that this explanation is not adequate to the current state of things. There biggest contentions would probably be 1. that there are non-material realities that demand non-material causes and 2. that there are limits to the process of adaptation.

I believe the first but I don't know enough about the second. So that's why I'm trying to get clarity.

Probably I need to begin with the basic definition. Can you explain to me what it means when you speak of "the change in the frequency of genetic information"?

I don't understand why frequency is the issue, so I probably need that explained first.

Thanks for your patience.

Andrew said...

KyCobb,

It dawns on me that maybe there are only two types of "fact" but it's hard to identify them. At first I thought maybe public facts and private facts, but that's not really the point at all.

It seems like the first would be "facts as perceived" and the second would be facts as what might or might not be perceived. Is the second what people mean by ontological facts?

Singring said...

'I'm sorry not to have responded sooner, but you must be patient with me. '

Take your time, a careful debate is usually much more productive than a rushed one.

'"There are various meanings given to evolution and within those given meanings it does not matter which I am using for the purposes of this discussion with the evasive Martin."'

This is exactly what I meant and I'm sorry if that got lost in the confusion of traing to debate two people at once. I am now focussed on the discusion with you so this hopefully won't happen again.

'So what I need to understand is, does the term evolution demand, in all uses, adaptation without limitation.'

I'm going to do my best to answer this question to your satisfaction. There's two angles from which we need to look at the question:

1.) What the term 'evolution' demands depends on how you define the term in the first place. For example, Ham & Co will frequently lump cosmology, chemistry, geology and whole bunch of other disparate topics in with 'evolution', which is not really an honest or correct thing to do.

In biology there are a number of definitions of evolution that are very similar, but differ in certain points - but all of them include the concept of adaptation driven by random mutation and natural selection either explicitly or implicitly.

In theory, that also includes the concept of 'adaptation without limitation', but there are so many restrictions in actuality that it makes no sense to speak of 'adaptation without limitations' in the context of evolution.

Which brings me to:

2.) Because of the evolutionary history and genetic constraints of organisms, there are practical limits to 'adaptation' - which is precisely why over 99.9% of species have gone extinct. One such constraint is the rate at which mutations occur. Another is the generation time. Both of these factors make it almost impossible for a tiger and a house cat to have 'evolved' from a pair of cats that walked off an ark 4,000 years ago. As I said before, it is Ken Ham who really believes in 'limitless adaptation', not evolutionary biologists.

'I'm sure neither Ken Ham nor Martin Cothran would have any trouble with the concept of evolution if it means adaptation or even, the one you helpfully provided: "the change in the frequency of genetic information in interbreeding populations."'

They might not have trouble with the concept, but they would have trouble with the consequences - one of which is that two distinct species can evolve out of one species - in other words, common ancestry - and that given enough time and teh right conditions, all species on the planet share one common ancestor. Another problem for Ham would be that populations that cannot interbreed are distinct species. Because that would mean that over 250,000 species of beetles 'evolved' from two beetles over 4,000 years. Even Ken Ham would be embarassed to propose such nonsense (I hope). This is exactly why Creationists always speak of 'kinds' of animals and then refuse to define what they mean by a 'kind'.

If you ever attend a Creationist lecture or presentation, make sure you ask them how they would define a 'kind'. I will bet you fifty bucks they will either not answer the question directly or they will give a definition identical to the definition of a biological species (populations that cannot interbreed successfully), which of course would render the whole idea of a global flood and Noah's ark more absurd than it is anyway.

KyCobb said...

Andrew,

"It seems like the first would be "facts as perceived" and the second would be facts as what might or might not be perceived. Is the second what people mean by ontological facts?"

I don't know. I did not take philosophy courses, so I truthfully could not say what an "ontological" fact is.