Evolution backward reasoning?

OK, here’s a question that will probably start off some sort of fight. Just what we needed around here, another argument.

In the grand battle between “evolution” and “creation” proponents, I have problems with both sides. But here I want to address one of my problems with the standard evolutionary preaching.

There have been many people who pointed out the fallacy of saying that since two legs was the optimum number, then God must have created us specifically and intially with that number. The point is that this uses backwards reasoning. If we had three arms or something, we would be saying “imagine if we only had two. Think of all the things that we couldn’t do! Thank God we have three!”

Ok, but aren’t evolutionists doing the same thing?

For all the talk about animals that have evolved elaborate camouflage, supposedly as a product of eons of evolution, there are those that stand out like beacons. Here I’m thinking of salmon who turn bright red just when there are bears around to smack them out of the river and eat them. If they were the color of riverbed, we’d be saying, “Evolution has provided them with protection. I mean, what would happen, if say, they were bright red? They’d be easy prey. Evolution has bred this out of the species.”

It seems that every time there seems to be some adaptive characteristic, people say “Look; evolution at work protecting the species.” And every time there is something that is a drawback, “Well, it doesn’t matter.” It all seems a little too easy and almost hypocritical to me.

Imagine if people had exoskeletons. We’d all be saying, “And evolution has of course provided us with protection from our environment. Without our exoskeleton, we’d be prey to all sorts of cuts and injuries that just bounce right off our exoskeleton.” But since we don’t, we say, well, it doesn’t matter.

Isn’t this all reasoning after the fact?

Well…yeah. That’s science. You look at the facts and base theories on those facts. I.e. Animal X procreated. Animal Y didn’t. Obviously Animal X did something right. You then theorize as to what it was that Animal X did right. Sometimes it may just be luck.

To paraphrase Sherlock Holmes, you don’t change the facts to fit theories.

Evolution isn’t perfect. It just so happens that even with certain disadvantages, these species have managaed to survive. The salmon you speak of, rather than evolving camouflage, merely eveolved mass reproduction. It’s not exactly a concious choice here.
As for the three arms business, it’s quite random. If a human had evolved with three arms or an exoskeleton and survived and flourished, then we’d have them wouldn’t we? It’s all about randomness.

Sincerely, SDStaff hopeful

You might be interested in some of the books by Stephen Jay Gould. He addresses some of the problems/misconceptions about evolution that you bring up. For example, people often talk about evolution as if it is consciously striving to produce the perfect creature, when, in reality, natural selection often produces outcomes that are just adequate for survival. (Yes, salmon get eaten by bears, but there are a lot more salmon than bears.)

Gould also talks in great detail about the “what if” question in his book “Wonderful Life.” It discusses an early period in natural history when there were apparently many more “basic” types of animals than there are today. Many of them disappeared in a catastrophic period of extinction, but he points out that the ones that survived (including the ones that eventually led to all modern animals) were not necessarily superior to the ones that didn’t. It was just luck of the draw.

One of the things my philosophy of science professor was careful to stress when we studied evolution is the misconception that all current traits have been selected “for” by the pressures of natural selection. While a bright pink bear would be selected against pretty quickly, there are traits that can be simply along for the ride: they aren’t selected for, they’re simply not selected against. We’re pretty sure by now that our appendices offer no survival advantage (among other mystifying organs); because we’ve survived via other traits, appendices may have the illusion of conveying some survival advantage.

To think otherwise is a fallacy on the part of some evolutionists, and not a problem with evolutionary theory. It seems perfectly sensible to me that some traits may be neutral.

Natural selection does not “work” at anything, least of all “protecting;” it is the description of an outcome, as mentioned earlier. Natural selection is the fact that one individual of a species survived to reproduce–not the species itself, natural selection is limited to local conditions–and that outcome increases the chances that the offspring will survive to reproduce, within the local conditions. But natural selection cannot “protect” a species by selecting for characteristics that will, say, be useful when the next 10-mile-wide asteroid hits. Natural selection is not predictive. So any use of active verbs to describe evolution and natural selection is inconsistent with the theory and its mechanism, and are at best straw men.

Such thinking is called teleology.
From Merriam Webster:

Main Entry: tel·e·ol·o·gy
Pronunciation: "te-lE-'ä-l&-jE, "tE-
Function: noun
Etymology: New Latin teleologia, from Greek tele-, telos end, purpose + -logia -logy – more at WHEEL
Date: 1740
1 a : the study of evidences of design in nature b : a doctrine (as in vitalism) that ends are immanent in nature c : a doctrine explaining phenomena by final causes
2 : the fact or character attributed to nature or natural processes of being directed toward an end or shaped by a purpose
3 : the use of design or purpose as an explanation of natural phenomena

  • tel·e·ol·o·gist /-jist/ noun

Nowhere in evolutionary theory does it say that every trait must be advantageous in every possible circumstance. Evolution also doesn’t say that we are optimized for dealing with every possible situation, so it’s usually pretty trivial to think of ways some species could be better protected against certain threats. If rabbits weighed 300 lbs they would not become dinner for bobcats! Or, like you said, if humans had exoskeletons we wouldn’t get as many cuts. But such “what if” games can be played for any combination of traits. If humans had exoskeletons, then you could find disadvantages to that and say, “we’d be better off without our exoskeletons”.

Re: salmon, you’re just looking at one small part of the picture. Maybe being red increases the risk to those salmon of being eaten by bears, but among all the threats to salmon, bears are probably not very high on the list. The redness could be selected for if it conveys enough of an advantage in other ways (perhaps being able to easily find mates?), even if it also had disadvantages, and it could also persist just by not being selected against.

Not really. The evidence for evolution is not based on organisms being optimally suited to handle every possible threat.

peas on earth

WOW! I like that word, Nickrz!! I have to try using it in several sentences…

As for the original question,

shows the standard mis-conception about evolution that leads to many of the attacks against it by ‘creationists.’ Evolution is the description of a process by which the myriad random genepool modifications that are thought to occur result through ‘natural selection’ in changes to species. In other words, evolution is a description of the end result, not a force in action. Obviously, for any species, there will be those units that have progeny that survive to procreate, and those that do not. The fact that I have a pink belly may make me easy pickings for a bear (actually a bad assumption, cause most of the time the belly isn’t easy to see from above), but if it helps me produce progeny that manage to procreate, then everything is hunky-dory.

The REAL trouble with evolution as a theory of how humans got here is when humans assume somehow that everything about them is ‘perfect’ having been the ultimate result of evolution. Personally, I have to question that, having had my appendix nearly blow up on me at 2 am one morning. :slight_smile:

Evolution as a theory fits the available facts reasonably well. The real trouble with it is that we can’t ever KNOW what really happened, so why bother worrying?

Thanks, guys (generic).

These are reasonable replies, and even better, support my theory! And who doesn’t want their theory supported?

So the conclusion around here seems to be that yes, there is a problem with such reasoning, and those that do it have committed the same sin as those who say that we’re “perfect” because God made us that way. Evolution is not a force itself, trying to make things happen.

But you have to admit that many, many times it is presented that way, even in textbooks. “Evolution has provided the species with…”

Arrrgghh… As I’ve said to high school chemistry classes, I may not be a brilliant scientist, but I’m a picky scientist (if indeed I have any real claim to the title at all), and that’s half way to being good right there. When textbooks present inaccuracies, it drives me crazy. I don’t mind making analogies, etc., but quotes like the one above are just plain wrong.

That reminds me, I have to rant on a moment, it even bugs me when the SAT I has a reading passage which describes an experiment where someone tried to see if having small, non-flying wings gave an insect a possible advantage in dispersing heat, thereby making it possible that proto-wings were selected for because of reasons other than flying. She said it could have, but then the passage says that she had provided proof of a transition between non-flying and flying insects.

She did nothing of the kind! She proved that it wasn’t out of the realm of imagination. I realize that SAT reading passages aren’t supposed to do anything but provide a context for questions, but it does put in the kids’ minds that it was proof. (And how does a heat dispersal organ end up developing the muscles and aerodynamics for flight? And where are the species who never got past the heat dispersal usage stage?)

Oh yeah, while I’m here on a stump, the SAT also asks for decimal answers to be given to three decimal points, even when the question clearly has measured values that are in only two significant figures. WHAT ARE THEY TRYING TO DO TO ME? Here I spend months and months TA-ing a high school chem class and ramming sig. fig.s down their throats, and ETS goes and throws it right out the window. I guess that’s what happens when you have math people writing the test, not scientists.

Only scientists use sigfigs. Mathematicians either use the whole answer or arbitrarily set a limit. For example 3/4 = 0.75, not 0.8 as sigfigs would show it as. Which one is more accurate? I personally hate sigfigs because they are a set of mildly complicated rules often misunderstood that often lessen the accuracy of an answer.

I understand that mathemeticians might not concentrate on sig. fig.s. But what is this bit about them making the answer less accurate? If you only measured your values to the hundredths value of the number ( the 3 in 23 for instance), then don’t use that value in a calculation and claim at the end that you know the calculated answer to the ten thousands part (the 4 in 7,594). To do so is to lie.

Not sure how one should get a point across to a HeadlessCow, but in engineering, sigfigs is where it’s at. Used right, they keep you advised as to just how much you know, and not more. The complement of this statement is that engineers don’t know everything. . .at least not yet.

Ray (ex-EE)

As for evolution, it’s just a passive sieve wired up to environmental history. If History had wanted salmon that eat bears, it would’ve. . .well. . .evolved them.

Ray (whatever would bring about my existence. . .say an individualized anthropic principle)


My vote is to move this to Great Debate. I’m tired of seeing this topic.


What people often fail to understand is evolution doesn’t do what is best it does what works.

Animals are put her basically to reproduce. Even if it isn’t a great feature as long as it continues to work (in other words the species continues to thrive) it won’t change.

An example of this is having one common passage for air and food. That isn’t the best solution but it works. And if it workd evolution doesn’t back up and change.

Try reading this book: The Blind Watchmaker by Richard Dawkins.

Evolutionary science IS after the fact.

If it wasn’t, it could adequately predict what creatures will evolve which characteristics.

If it was a real science, it could show with a predicted error what life can evolve from certain environmental conditions. I.E. from a complete evolutionary theory, we should know what kind of life could exist, if any, within a certain degree of error, exists on Mars, before getting there.

Evolutionary science IS after the fact.

One beer is less than two beers.

Evolution is not science. A science is an area of study which attempts to deduce what rules govern how things happen, in order to be able to predict what things will happen in the future. Physics, biology, psychology (ok, just kidding about that one), etc.

Evolution is first of all a theory. It is a theory postulated as to how differing species developed. It is based in part on observing the evidence of presently non-existent species, and in part on observing the behaviour of presently surviving species. If you want to understand the theory, you should start with the works of Charles Darwin, in which the theory that evolution of the species by natural selection is originally (so I was taught) proposed.

I do not know if it has ever been established that natural selection actually can result in the development of a new species. Perhaps someone knows of a controlled experiement resulting in such a change?

There is nothing wrong with attempting to explain data as it appears - the trick is doing so with the correct reason, as all flatearthers know :wink:

How can you say that evolution is a science. I was always taught that science has to be:

  1. Observable
  2. Demonstratable
  3. Repeatable

None of these apply to the evolutionary theory.