12-05-2003 20:37									#1
	Yes, it's another damned evolution question... Support Apolyton, buy GURPS/ Alpha Centauri

But first, the disclaimer/notice(it worked last time, maybe it'll work again):
I AM NOT A FUNDAMENTALIST ATTACKING EVOLUTION. NOR AM I AN ATHEIST ATTACKING RELIGION. PERSONAL ATTACKS TREATING ME AS SUCH WILL GET NO RESPONSE FROM ME OTHER THAN A SPOT ON MY IGNORE LIST WITH YAVOON. THANK YOU.
AND PLEASE DON'T THREADJACK. PROSELYTIZE SOMEWHERE ELSE, I'M POSSESSIVE OF MY THREADS.

With that said, I seem to remember a response to a creationist in a previous thread that went along the lines of, "stop reading crap like Philip Johnson and look up 'transitional forms' from a reputable source."
As it so happens, I've since read Johnson's stuff(long story), and his argument seems aware of transitional forms but maintains that they do not exist, or at least haven't been found. Which is to say, no real, significant tfs that bridge the gaps between evolving types. There was a feathery dinosaur called archeopteryx and there is a primitive bird called the hoatzin, but he maintains to the effect that none of the freakish creatures that should have gone between have been found. I myself also wonder how such tfs could have reproduced unless by staggering coincidence similar aberrations appeared at the same time, seeing as cross-species breeding nowadays results in sterile offspring most of the time(tiglons, mules, etc.).
I ask mostly in the spirit of an inquiring mind here: do such forms exist, and if so, could somebody point me to a resource describing them? I've tried web searching but all I got was links to unfounded diatribes by either side of the issue. I'd like to reiterate that this is not an attack on the theory as such...

	12-05-2003 21:12									#2
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http://www.talkorigins.org/faqs/faq-transitional.html

Claims that there are no "transitional" fossils are bogus, because Creationists move the goal post whenever the evidence is presented to them. We have plenty of examples in the fossil record of marked "transition" in animals. Keep in mind that the further back you go, the more difficult it is to find intact fossils. Since speciesation occured such a long time ago in geologic history, the likelihood of finding fossils from that time is very remote.

	12-05-2003 21:41									#3
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When I was still a university student I was lucky enough to take a class on evolution and the fossil record in which we got to see several claims made by creationists such as Johnson. Ussually, the creationist will stand around demanding a "missing link" or transitional form (which he claims is missing) then once a transitional form is found they go about trying to deny it is similiar species.

Personally, I think their sceptism improves the science by making scientists extra careful of what they publish. In the end these people won't except anything which doesn't confirm their religious beliefs so they cannot be concidered scientists.

	12-05-2003 21:42									#4
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I've seen a lot of stuff on discovery channel tracing, with fossils, the evolution of man...

	12-05-2003 21:46									#5
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Lastly, you also have to remember that much of our understanding of the deep fossil record is based upon a handful of fossils from each species. That means scientists are never sure if they have a typical or atypical example of a given species. The scientific method just demands that people make up and test plausable theories based upon the evidience at hand so when new evidience surfaces (like when a new fossil is discovered) then you adjust your theory.

Many creationists seize upon this adjustmant as saying all of evolution is wrong because scientists move species A from being a sub-species of B into being it's own free standing species. The reality is the over all system is fine and the only thing people are arguing about is where individual fossils fit in.

	12-05-2003 21:52									#6
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Of course, since science is based on making predictions, just ask a Creationist what predictions he can make based on a Creation model, and an explanation for the transitional fossils we do have (like the walking whale found in 1993), and the varying levels of fossil strata that strongly support the evolutionary model.

	12-05-2003 21:56									#7
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	12-05-2003 21:59									#8
	Re: Yes, it's another damned evolution question... Support Apolyton, pre-order Civilization IV

quote: Originally posted by Elok With that said, I seem to remember a response to a creationist in a previous thread that went along the lines of, "stop reading crap like Philip Johnson and look up 'transitional forms' from a reputable source."

That's yours truly

quote: Originally posted by Elok As it so happens, I've since read Johnson's stuff(long story), and his argument seems aware of transitional forms but maintains that they do not exist, or at least haven't been found. Which is to say, no real, significant tfs that bridge the gaps between evolving types.

That's one of my biggest problems with Philip Johnson and his ilk. When overwhelming evidence presents itself, they just dismiss it with the wave of a hand.

Creationist, "I don't see how you can say birds evolved from dinosaurs. Where are the transitional forms?"

Evolutionist (goes around digging, eventually finds something that fits), "Hey, look at this marvellous fossil. It has both bird and dinosaur features. It is unmistakably a transitional form between birds and dinosaurs."

Creationist, "No it's not. It's just a freak accident."

Evolutionist, "What? WHAT??!"

quote: Originally posted by Elok I myself also wonder how such tfs could have reproduced unless by staggering coincidence similar aberrations appeared at the same time, seeing as cross-species breeding nowadays results in sterile offspring most of the time(tiglons, mules, etc.).

Why do you need these coincidences? These transitional forms could not be a result of corss-species breeding. For one thing, birds didn't exist. Anyway, As environmental conditions changed rapidly, individuals with certain mutations are favoured. As a result, they could survive and pass their genes to the next generation.

quote: Originally posted by Elok I ask mostly in the spirit of an inquiring mind here: do such forms exist, and if so, could somebody point me to a resource describing them?

Do they exist? No. Did they? Yes, of course. Otherwise, where did the fossils come from?

	13-05-2003 01:06									#9
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Well, UR, my point about the propagation was that the development of new species involves, naturally, a change in DNA. Different species tend to have different numbers of chromosomes(don't goldfish have 96 or something ridiculous like that?). Mutations resulting in different numbers of chromosomes in humans typically lead to things like Down's or Klinefelter's syndrome, which cause sterility, deformity, or both. Extra chromosomes have a hard time fusing with normal DNA into viable offspring. At least, that's the explanation I always heard. Now, different numbers of chromosomes aren't necessarily related to the development of difference between species, which is why this is only a minor, possible point of confusion w/me. I asked my dad this question once-he told me that chromosomal organization is an arbitrary biological filing system not related to viability. It still seems strange to me though...I'm not explaining myself very well, am I?
Boris: I think the word is speciation, BTW. Anyhow, isn't it a gradually ongoing process? The human race, as discerned from primitive pseudo-hominids, is only, what, two million? Pretty short time in the grand scheme of things. Not that far back. I thought it was pretty much dogma that evolution is ongoing. Actually, if it comes to that I guess there is a pretty smooth chain of developing hominids, just not for earlier species...so you have a solid point.

	13-05-2003 01:59									#10
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Elok:

On mutations:

http://www.talkorigins.org/faqs/mutations.html

talkorigins really is an incredible resource, I would advise giving it a very thorough reading when you have time.

And yeah, I was originally going to say something involving the word "species," but got short and time and lazy and added the -ization without deleting the rest. Oopsie.

Certainly, evolution is a gradually ongoing process [EDIT: not necessarily always, however, as Neutrino points out below, i.e. punctuated equilibrium]. We've even seen speciation occur, in a particular kind of dog that was transplanted away from its native habitat and, over 100 years, changed so it could no longer breed with the original species (I forget the instance, will have to look it up).

Last edited by Boris Godunov on 13-05-2003 at 02:30

	13-05-2003 02:27									#11
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Hmm, I just took a final exam in my Evolution class last week

Speciation is the result of many possible factors, driven by both natural selection and neutral mutations.


To answer your question to the best of my knowledge, Gould came up with the idea of a 'punctuated equilibruim' model of evolution, where evolution basically occurs in spurts rather than at a constant rate (phyletic gradualism). Actual evidence from fossil records show evidence of both punctuated equilibria and phyletic gradualism. If a population of a species is undergoing rapid evolutionary change then the chance that fossils will be found for the 'transition' forms will be smaller than the forms that exist for a long time. This is just one of the possible explanations for holes in the fossil record. Note that similar traits can evolve indepently of each other -- i.e. convergent evolution and homologous traits.

As for hybrid inviability, it can result from difference in chromosome number. Humans have 46 c-somes - our diploid # (2n). Our haploid # is 23 (n). Gametes - sperm, eggs - are almost always haploid in the animal world. If the diploid # is odd, then the hybrid will most likely be sterile.

IMO the transitional forms were produced by a combination of hybridization and punctuated equilibrium evolution. Hybridization is hard to define concretely (hard to classify what exactly constitutes a species).

Hope this makes sense, groggy from lack of sleep.

	13-05-2003 04:04									#12
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quote: Actual evidence from fossil records show evidence of both punctuated equilibria and phyletic gradualism.

Do both models allow for the two to coexist? I would be interested to see how they workaround this problem.

quote: Hybridization is hard to define concretely (hard to classify what exactly constitutes a species).

Nice to see this come from a non-Creationist. Clearly the non-Creationists are allowed to critique where the creationists are not.

	13-05-2003 04:23									#13
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quote: Do both models allow for the two to coexist? I would be interested to see how they workaround this problem.

Most evolution is a mixture of the two. Punctuated equilibria and phyletic gradualism represent the 2 extremes. P.E. states that in between the rapid periods of change, the species remains stagnant. If we introduce phyletic gradualism into this scheme, the stagnant periods are replaced by a somewhat constant change. So we can have abrupt changes once in a while, and between those changes we can have a constant rate of change.

The whole concept of a species is rather hard to define - after all, how do we assign discrete groups to a continuous set (DNA/RNA). One of the topics that's being debated now in this field is how best to define a species. Personally, I prefer the Biological Species Concept (BSC) - species are groups of interbreeding natural populations that are reproductively isolated from other such groups [Mayr, and Dobzhansky and Huxley].

	13-05-2003 04:34									#14
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quote: Originally posted by obiwan18 Nice to see this come from a non-Creationist. Clearly the non-Creationists are allowed to critique where the creationists are not.

When has an evolutionist ever asserted otherwise? And when have they criticized Creationists should they assert such a thing?

Actually, it is Creationists who tend to use this as a strawman. They assert that evolutionists believe in concrete hybridization, then argue against it and think they've scored some sort of tactical victory, when in fact they are arguing a position evolutionists tend not to hold, and one that is unneccessary for the mechanics of evolution.

	13-05-2003 12:22									#15
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quote: Originally posted by Neutrino Personally, I prefer the Biological Species Concept (BSC) - species are groups of interbreeding natural populations that are reproductively isolated from other such groups [Mayr, and Dobzhansky and Huxley].

That seems to be the most accepted definition.

	13-05-2003 12:32									#16
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Once again, I am going to ask the old chestnut: how could free-will evolve?

	13-05-2003 12:35									#17
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quote: Originally posted by Elok Well, UR, my point about the propagation was that the development of new species involves, naturally, a change in DNA. Different species tend to have different numbers of chromosomes(don't goldfish have 96 or something ridiculous like that?).

It depends. Not all species have a unique number of chromosomes. In fact, species closely related, such as the Great Apes, have the same number of chromosomes. In other words, there are all sorts of mutations and not all of them involve making an extra copy of a chromosome.

	13-05-2003 12:36									#18
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quote: Originally posted by Rogan Josh Once again, I am going to ask the old chestnut: how could free-will evolve?

Why do you assume that freewill has evolved?

	13-05-2003 13:02									#19
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Urban:

quote: It depends. Not all species have a unique number of chromosomes. In fact, species closely related, such as the Great Apes, have the same number of chromosomes. In other words, there are all sorts of mutations and not all of them involve making an extra copy of a chromosome.

True, but I think you missed the point. Taking any two species with different number of chromosomes, how can we explain one turning into the other? If we have the same ancestor as chimpansees, how did we lose two chromosomes (or gain, I can never remember)?

I think the answer is the same you get pretty much every time you consider mutations: that an extra chromosome isn't always detrimental. Most of the time, even overwhelmingly so, but every once in a while you get an extra chromosome that actually helps. And rarer still, you get an extra chromosome that not only helps, you manage to pass it on to an offspring.

BTW, about 1 in every 500 females are born with an extra Y chromosome. Most never realize it, as it usually takes a DNA test to discover. Apart from being barred from the olympics, I don't think there is any detrimental effects.

	13-05-2003 13:13									#20
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quote: Originally posted by Urban Ranger Why do you assume that freewill has evolved?

I'm sorry - I thought this was your position. What other mechanism do you suggest? Divine intervention?

	13-05-2003 13:21									#21
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Rogan:

First, you need to define "free will" and establish that we actually have it.

Good luck.

As for the difference between human and chimp chromosome count: we have 23 pairs, the other great apes have 24. This was due to the fusion of two chromosomes, and the evidence for this is the fact that the telomeres at the ends of the fused chromosomes still exist in the middle of the new chromosome.

	13-05-2003 13:25									#22
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quote: As for the difference between human and chimp chromosome count: we have 23 pairs, the other great apes have 24. This was due to the fusion of two chromosomes, and the evidence for this is the fact that the telomeres at the ends of the fused chromosomes still exist in the middle of the new chromosome.

GAAAAH!! You made me learn something today! I was *this* close to going home, but decided to take one last peek at apolyton, and a whole days non-efforts are wasted! How will i ever achieve nirvana this way?

That is pretty neat though. I never knew

	13-05-2003 13:32									#23
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quote: Originally posted by Jack the Bodiless First, you need to define "free will" and establish that we actually have it.

1. The ability to behave in ways which are not dictated by our initial conditions.

2. I have it - don't you? Did you make that post, or was it the laws of physics?

	13-05-2003 13:43									#24
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1. doesn't exist.
2. since it doesn't exist, you don't have it, as well.

	13-05-2003 13:49									#25
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There are plenty of transitional fossils in just the fossil record for humans from upright walking apes to modern humans with a progression occuring over ~4 million years. The interesting time frame to me is what happened during the last 300,000 years, the hominid believed to be the common predecessor of all humans over the last ~400,000 years - homo erectus - was around since 1.6-1.9 mya and remained quite static wrt evolution for more than a million years, then around 250-350,000 years ago, something happened leading to us. What makes this even more curious is that fossils of homo erectus have been found in Indonesia dated as recently as 40-60,000 years ago, living AFTER anatomically modern humans had already "evolved" in Africa.

	13-05-2003 13:56									#26
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there is nothing surprising about it. It's not easy to reach Java from africa. You have to develope map making first.

	13-05-2003 14:10									#27
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quote: 2. I have it - don't you? Did you make that post, or was it the laws of physics?

Alexander's Horse has already noted that I have no free will in this matter.

I was compelled to post, in response to your post. My button was pressed, and I reacted. I am a machine.

	13-05-2003 14:40									#28
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I do believe in evolution (don't get me wrong!) but my major worry would really be the apparent lack of diversity in life forms on Earth. There seem like quite a few, but shouldn't there be more?

For example, why do all mammals have eyes on the front/side of their faces? Wouldn't antelopes benefit from having one on the top of their head so that they could have vision when they are grazing? Predators have them on the front to give them ability to judge distances - but why not also have one behind? Also, there are plenty of creatures who mainly use hearing rather than sight, but still have two (fairly useless) eyes - why are there none with one? Does this mean that all mammals (or I suppose dinosaurs) are decended from the same 2-eyed creatures?

Hearing is another example. Why are all hearing systems basically the same? There must be thousands of ways of detecting vibrations, but only a few of them have evolved. Why?

In genetic terms (or function terms) an elephant is really not that different to a giraffe. It is not terribly long since they diverged in the genetic tree. I don't understand why there isn't a completely differently designed animal, perhaps with a genetic structure which diverged much earlier.

I suspect that there will be some reason for this found sometime - such as evolution sometimes happening in big jumps, soI am not too worried. But I am still uncomfortable with the traditional ideas.

	13-05-2003 14:51									#29
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quote: Hearing is another example. Why are all hearing systems basically the same? There must be thousands of ways of detecting vibrations, but only a few of them have evolved. Why?

because hearing has developed early on, and genetically, there is a very slim chance of developing an alternative hearing system, so what is usually made are upgades and modifications to existing systems. that's the rule. of course, there are exceptions.

	13-05-2003 15:05									#30
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quote: For example, why do all mammals have eyes on the front/side of their faces? Wouldn't antelopes benefit from having one on the top of their head so that they could have vision when they are grazing? Predators have them on the front to give them ability to judge distances - but why not also have one behind? Also, there are plenty of creatures who mainly use hearing rather than sight, but still have two (fairly useless) eyes - why are there none with one? Does this mean that all mammals (or I suppose dinosaurs) are decended from the same 2-eyed creatures?

Yes, they are. And as a random rearrangement of organs would almost certainly be fatal, mechanisms have evolved which tend to keep organs in pretty much the same configuration relative to each other: a configuration which works. This would be a better argument against "intelligent design" rather than evolution.

quote: Hearing is another example. Why are all hearing systems basically the same? There must be thousands of ways of detecting vibrations, but only a few of them have evolved. Why?

There are various mechanisms for sensing vibrations in air, water, earth, a spider's web, and so forth. Species with what we would recognize as "ears" are a minority. But they're the ones we are most familiar with, because they include mammals and birds. Ears evolved from gill cavities in fish: they didn't need them for respiration after they crawled onto land, so they were left with redundant air-filled resonating cavities. The bones of the innner ear developed from the same structures that support the gills in fish, and are generated from similar genes. And Azazel is right, there isn't much incentive or opportunity for mammals to evolve a whole new hearing system now that they already have one that does the job.

quote: In genetic terms (or function terms) an elephant is really not that different to a giraffe. It is not terribly long since they diverged in the genetic tree. I don't understand why there isn't a completely differently designed animal, perhaps with a genetic structure which diverged much earlier.

Not sure what you're getting at there. The locust diverged much earlier, and isn't much like an elephant or a giraffe. Actually, the closest living relatives of the elephant are the sirenians (dugongs and manatees) and the hyrax.