Is the theory of evolution "testable"?

General Questions
#1

First off, I’m a great fan of the theory of evolution. I think it’s got a few kinks, but overall - good theory. I certainly don’t think intelligent design or creationism offer a better theory.

But after reading this article on the University of California being sued by Xtian high school students for saying they don’t have the education requirement for incoming freshman, a friend pointed out this part:

She then asked, “So how exactly is evolution testable? I mean, we can breed dogs to have flat faces and teeny legs, but does that really test that evolution happened without any outside influence?”

And I said, “Uh…well…ya see…”

Obviously, my rapier wit astounded her, and I won the argument hands-down. Only in the not doing that at all sense. So I need Doper help!

#2

Sure evolution is testable. For example, the theory makes the prediction that species extremely similar in morphology, divided by some geographic barrier, will also be extremely similar in genetic material. So you go out and examine species’ morphology (just like Darwin did with Finches on the Galapagos Islands), then you measure their similarity in DNA (Darwin couldn’t do this, but I’m sure he would have loved to)… you’ve tested the prediction, and guess what you find?

You could also predict from evolutionary theory that somewhere out there are fossils that share characteristics of major taxonomic groups that are now quite distinct (there should be such fossils because those groups would have had a common ancestor). You dig for fossils, and then you turn up things like Archaeopteryx, or you get surprised by still extant ones like the Coelocanth.

The problem with your friend’s question is right here:

She’s actually asking from a Creationist assumption, that science has to show there was no outside influence. This is impossible, especially when the outside influence is an invisible, intangible, omnipotent, (yet sandal-wearing) fellow in the sky. I can’t show that an invisible intangible guy didn’t flick crumbs off my muffin this morning: how would I go about testing that idea?! Science isn’t interested in untestable influences. It is interested in what can be tested.

#3

Just so. Evolutionary theory isn’t about proving that there is no god. It is about explaining observations in testable fashion. This is getting old by now, but one of the problems with the ID position is that it essentially says to science, “Ok, then, prove that there ISN’T a designer.” It’s just about impossible to prove a negative. And that’s not the responsibility of those who claim that evolution is a substantive explanation of life on earth. Science is about using evidence to support suppositions and assertions. No one can tell us WHY evolution and natural selection are at work, but they are. That, we can support with evidence. That’s the whole problem with the so-called debate. I suggest you search any of the recent threads on ID and evolution and you’ll see a number of articulate posts that will help you in your discussions. xo, C.

#4

Of course evolution has outside influences, if by “outside” you mean outside of biology. The shifting of continents was an outside influence. The Earth shedding its primordial heat was an outside influence. The solar cycle still is an outside influence. The K-T Impactor 65 million years ago was an outside influence.

And we also have a pretty good handle on why evolution occurs. The premise of natural selection is tautological: Those that die, die, and those that live, live (or more precisely, those that don’t reproduce, don’t reproduce, and those that reproduce, reproduce). Does one really need to ask why that’s true?

#5

My point was that apparently, many people are asking why that’s true, and the fact is that at some point, all science ends with that question. For many of us, the answer that is perfectly satisfactory is that that’s just the way the universe works. Clearly, many people need something else.

#6

Evolution never claims that there was no outside influence. For all we know, God, Shiva, Ahura Mazda, or a superintelligent band of space aliens have been guiding our evolution.

But to affirmatively say that one of those deities actually has done it (per ID or theistic evolution) is NOT in the realm of science. Science says, “things have changed,” whether it has been guided or not.

If confronted with an impossibility, such as “the eye could not have evolved without the simultaneous gain of 6 different functions,” then the scientific answer is “we don’t know how it happened,” not “God must have done it.”

If wackos insist on legislating the supernatural into science classrooms, I vote that science teachers respond by teaching that our evolution has been guided by space aliens.

#7

“Testable” of course in a scientific context does not mean just that a something can be demonstrated by means of experiments. As others have indicated, it just means that you can make predictions based on your hypothesis, and then test whether those predictions are true or not. These tests can be based on purely observational data. Evolutionary theory has been subjected to many thousands of tests of this nature, and has not been falsified (which is the best you can do in a scientific context).

As others have indicated, the hypothesis that there was some invisible undetectable influence on evolutionary events is untestable and therefore is outside the realm of science. The whole question indicates a basic misunderstanding of what science is all about.

#8

And even without those outside influences, there are still significant inside influences. Species change not only in reaction the earth’s changes, but in response to changes in their fellow species: prey, predators, parasites, and competitors.

As one of many examples, Richard Dawkins described the cheetah and the antelope as being locked in a never-ending “arms race”, one that slowly unfolds over millions of years. Antelope evolve to better detect and run away from cheetahs. Cheetahs evolve to better hunt down antelope. Repeat indefinitely.

So even on a static planet — which Earth certainly isn’t anyway — you’d expect to see evolution happening. No intelligent design is necessary.

#9

I think a lot of confusions with evolution would end if we just separate two completely different aspects of it.

The math theory, that does not need evidence, since it can be derived from set theory and formal logic, and it can be tested using any number of computer algorithms, as simple as John Conway’s Game of Life. If the logic is consistent, then the theory is true, regardless of how it affects biology.

The biological evolution theory, which says that for the some time ago certain strings of hydrocarbons fit the mathematical model and started evolving, which can be tested by fitting modern and historical evidence to the mathematical model(which is already proven)

This is akin to the problems people had with heliocentric models of the universe. There’s also two aspects here:

Mathematical: If two bodies attract according to given rules(law of gravity), they can orbit each other.

Physical: It seems that bodies attract each other, so there must be something orbiting something here.

Now any creationist argument against evolution of heliocentric solar system would have to bring in evidence against the Physical/Biological parts of it, NOT mathematical. Unless someone brave is ready to admit that either the postulates of math do not lead to those theorems, or that the postulates of math cannot be used to model the real world, opposers are stuck with arguing that the model fits the evidence, not that the model is faulty.

#10

Ahh! Good! I knew there was a basic problem there I just wasn’t seeing. Too much blood in my caffeine stream this morning.

And there’s the other part of it, in nice neat lay-speak.

#11

To criticize myself here: I apologize for the bad modifying phrase. Richard Dawkins is not himself an example of predator-prey evolution. Or if he is, that’s all beside the point I was making.

Astronomy and geology, just to name two other fields, have the same “problem” your friend is objecting to. You can’t build stars or continents in the laboratory and then watch what happens to them. This inconvenient fact doesn’t make these disciplines unreliable, or a big bunches of wishful guesswork. It just means (as already said for evolutionary biology) that they are observational sciences and not experimental.

#12

I read a book a while back that talked about testing evolution, I think it refered to Darwin’s Finches in the title. Some scientists went back and looked at the finches that so facinated Darwin. The scientists did a load of observations about available seeds and beak size and time it took the finches to eat the seed and how much they got out of the seed. They tried to see if their observation could reveal anything about evolution.

As I recall, they found that mathematical analysis showed that there were niches, beak lenghts that seemed to confer some advantage in that microenvironment, and the finches on the island seemed to be evolving to fit the niches on the island. I don’t remember it all that clearly, does anyone else know more of that book?

#13

Actually, there are a couple of predictions that the theory of natural selection makes that are testable, or at least observable. The theory holds in part that random genetic mutations occur such that over enough generations a given population with no selection pressure will experience genetic drift. This means that if a population of a species is split up, the separated populations will diverge genetically when under no selection pressure. If the populations are of a species that undergoes sexual reproduction, that means that if enough generations go by, the two populations will be unable to mate with one another if they are later reintroduced to each other. If I recall correctly, this has actually been observed in the laboratory for some species with a short reproductive cycle.

On the other hand, the theory of intelligent design holds that genetic changes are due to some entity that shifts species to be ideal for the environment in which they live. You would have to believe that this IPU (Invisible Pink Unicorn) took the time to enter the laboratory over a period of, say, 40 years, manipulating the genetic code of these two populations for some unknowable reason that makes them display behavior that mimics the exact expected behavior suggested by the theory of natural selection.

#14

Sounds like The Beak of the Finch, by Jonathan Weiner.

#15

Evolution would predict that micro-organisms that breed multiple generations in an observable amount of time should be seen to adapt to changing conditions. This prediction has been tested in both laboratory and natural conditions and found to be true. Evolution has been tested.

#16

Dude, the IPU is so 1990’s. Believe on the Flying Spaghetti Monster and thou shalt be saved.

#17

All the creationists I know then say: “Micro evolution has been observed, but not macro evolution.” My response is simply: what do you think happens when microevolution goes on for thousands to millions of years?

It’s amazing to think that the huge amount of evidence that shows evolution is a pretty solid theory, and a surprising proportion of the population would rather take a literal translation of a book written 5,000 years ago.

(FWIW, I’m a Christian, but believe that the Bible’s creation story is a big metaphor…God:“I made the universe.” Moses:“How?” God:“Got 500 years to listen to the basic science you don’t know before we get into quantum physics, genetics, biology, and advanced chemistry?” Moses:“um, no, I’ll just write that you made it.”)

#18

There’s a really cute short sci-fi story with this premise… actually Moses comes down and tells Aaron (I think) to write the history of the last four billion years on Earth for the book of Genesis. Aaron dissuades him based on the cost of papyrus and demands on his time, so Moses sighs, and says “OK, seven days.”

I think it’s Asimov, but I’m not sure.

#19

Evolution has been observed, but not intelligent design.

#20

I completely agree with you. I don’t understand the logic. The ID arguments are basically a thought experiment…it’s like: Evolution doesn’t make sense to me, but intelligent design does, so that must be the way it is, even though all the evidence points to evolution right now.