h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Sorry about that, Gif.

Okay, now that you've clarified your position, I can understand what you mean. And, really, it's impossible to debate. All I can really say is that whatever happened, I believe God was involved. And I also believe that somehow the "truth" of things can be found in the Bible and in the palientological/historical record.

It's not much of a conclusion, but it's maybe as close as we can get without rehashing the entire thing. *shrug*

-Eagle 1

I'm Ste!

Montana: "...what I meant was that if you feel the need to correct creationists based on the fact that their science is wrong, then why are you so surprised that they're trying to tell you *your* science is wrong, and it doesn't fit *their* principles?"
The way you describe it makes it sound like we're having a rational, perfectly logical scientific debate. That sort of thing is not possible with creationists. I am suprised when they respond with their version of evolution that fits their dogma because it is wrong. There's no two ways about, no fluffy happy middle ground; the lies that they spread about evolution are just plain incorrect. Also, as soon as you try and shoehorn science into an agenda it is bound to get warped.

"Furthermore, isn't part of the solution to the mess knowing where each side is coming from?"
Trying not to sound too arrogant, but I know exactly where they are coming from, as you hinted, it is them who do not have the capacity for thought outside their small world (wow, I'm harsh with these lot nowadays).

Potholer (hello again, sir ): "Reasonable debate about particular bits of science is another matter, but it requires some kind of factual common ground before the debate can be of any use."
Agreed, and your common-or-garden creationist only has the misinformation passed down from the Institute of Creation Research (http://www.icr.org/ look! we have white coats and everything!) and no real grounding in biology, so it really doesn't take much to tear down their paper-thin points. Which then inevitably leads to them resorting to bloody-minded stubborness .

Gif:
I think ID just points to the complexity of life and says "that cannot happen by chance" (without even bothering to look at if it could, or if it does). ID focused towards the evolution of man is more akin to the Anthropic Principle (anti-Copernican rubbish). And the "irreducible complexity" comes down to a lack of understanding about molecular evolution.

You describe punctuated equilibrium very well and I never really considered that mankind was in one of the "plateaus" before. Scary stuff. We will only start to evolve again when enough of us are dying, as with the AIDS epidemic in Africa (as I mentioned in a previous post) and malaria.

"On an unrelated point, surely if evolution has a purpose, it's not random, and therefore not evolution?"
I think it's very important to note that evolution is not random, it is made up of random and non-random forces. It is unguided, unconscious, but it has rules. The most obvious being natural selection, where the environment automatically chooses the most suited (common sense really).

On that note, if evolution WAS guided by a consciousness, would you really be happy with that situation? When I look at the struggle for existence that is life, all I see pitiless indifference. If there IS a consciousness helping evolution along then it is not one that I want to associate myself with because evolution is cruel, heartless and full of fear and death for all involved. That's why we developed medicine to opt out of this misery. What does everyone think?

Eagle 1:
I have nothing but respect for you. Creationists could learn a lot from you.

I have a VERY good article from Natural History Magazine here, if you're interested in this debate in the slightest I would HIGHLY recommend reading it. It starts of with four creationists stating their position and then some real scientists critically examine them, it covers all of the main creationists subjects (i.e., the ones discussed here): http://www.actionbioscience.org/evolution/nhmag.html it goes into a lot more detail than you usually see with this debate.



Ste

Okay, sitting in an internet cafe it would just cost me too much to get into this. And I think most of my arguments can be found in the backlog.

In Malaysia a large population is Muslim and Christian, I wonder if I will get burned on the stake as a heretic.

apparently, I'm Ste's 's advocate! Ste, dear, did you see the paranthetical statement after that...that this is assuming the creationist are being logical, and most of the time, they aren't?

Gif, when you say "punctuated equilibrium," does that mean that there are necessary surges in evolution? So everything goes along pretty much the same for a while, and then, in response to something fairly cataclismic, evolution occurs?

I was agreeing with you!

Punctuated equilibrium was a modification of Darwins idea that said that life evolved in constant tiny little increments. It came about because the evidence in the fossil record conflicted with Darwins view. Darwin thought that as more and more fossils were found the gaps fossil record would be "filled in", with the "transitional species" showing how one species evolved into another. Suffice to say these species never emerged (something that creationists like to remind people of). Hence the idea of evolution as a steady-state process punctuated by periods of rapid evolution. It makes sense really, if the environment that the organism is in isn't changing, then it is unspurising that the organism doesn't change. When environmental change does occur the ones that just happen to be suited to these new conditions survive (something that the creationists conveniently ignore or don't know about).



Ste

So the changes are in response to something that hasn't happened yet? Or am I confused?

(which is certainly possible...unlike all of you science types, I am approaching this from a historian's standpoint)

Imagine a population of animals (of the same species), each of their individual genomes is pretty much the same. Over time mutation, sex, and other elements mess and mix all of these genomes up slightly, each in individual ways with the result that within this population there is a lot of varation at the genetic level. This is happening all of the time.

Then, along comes a dramatic change in the climate and the animals' habitat suddenly changes. The individuals in the population that by chance happen to be best suited to the new climate (the variation, as mentioned before has, by chance, given them the genetic makeup to deal with the change) are naturally selected; they will thrive more than the individuals that are not (this is what's known as a genetic bottleneck).

So, genes and genomes are mutating and being mixed up all of the time *which enables* a population to adapt to a changing environment.

Ste

Ah! Now I get it. Thanks.

The most famous such change of environment occurred about sixtyfive million years ago when a meteor strike wiped out the dinosaurs. The first clue to this was found in a thin layer of clay that lies on what is known as the KT boundary (between geological strata of more than/less than sixty five million years old. This clay contained high levels of iridium, an element uncommon on earth but common in meteorites. This is also a good example of the way different scientific disciplines work together in solving puzzles.


Noggin

*searching her memory for dim recollections of undergraduate minor in geology*

wasn't there something about the magnetic poles shifting, as well? Wouldn't that create a slow evolutionary process that would be completed by the dying off of those who aren't adapted?

Cheers Ste. Yes, I agree with your opinions on I.D. Frustratingly, I can only download the first 2 paragraphs of the article you referenced. www.icr.org is always good for a giggle, my fave article is their visit to the Natural History Museum in London and their relief that it's not a 'Cathedral to Atheism'.

Montana: Magnetic poles do reverse every few thousand years, and that causes molten magnetic rocks to set in different directions. This provides us with a 'clock' to date rocks (lots of magnetic reversals = a long time), so it is a good argument against a young Earth. I am not sure it would have any direct effect on animal populations, though. Possibly migrating animals might get lost and freeze.

So a general question to all: How would you say that something like the liver (or any other major organ) evolved?

Gif

Actually, good 'ol Google has (nearly) the whole thing cached. It's also available at http://www.evcforum.net/RefLib/NaturalHistory_200204_SpecialReport.html

Gif

Does punctuated equilibrium challenge the idea that natural selection occurs at a constant rate, or that mutation occurs at a constant rate? My understanding was that the theory proposed it was the latter, that somehow, mutations speeded up at certain times, enabling rapid adaption to whatever new environment the creatures were exposed to.

Although most people will accept nowadays that natural selection is highly variable and punctuated, as evidenced by the KT mass-extinction (one of many), recent ice ages, even more recent effects of mankind introducing new species into places that had no defenses for such species, plus experience with diseases such as AIDS and the 1918 flu; I thought that the evidence for accelerated mutation over short time periods was less clear.

Punctuated equilibrium (I believe it was Gould's phrase - although the abbreviation of 'punk eek' sends shivers down the spine) was initially unpopular because it sounded like Cuvier's catastrophism.
Essentially, punctuated equilibrium is as follows; Longish periods of relative evrironmental stability during which species become established and adapted to available niches are occasionally interrupted by severe environmental crises, be they in the shape of glbal warming, massive ice-age, extreme volcanism, or the infamous and over-rated bolide impact on the K-T boundary (A706862).
The important thing to focus on is not so much the nature of the catastrophe, but the niches that become available after the event. In the unlikely event that a peculiar disease wipes out all life except for insects, bacteria, rabbits and snakes, the niches previously occupied by all other animals will eventually be filled by the animals left, once sufficient adaption has taken place. This is not to say that animals will 'decide' to adapt, but that within any sufficiently large population, there will be 'species drift' enough to produce, say, rabbits that are better suited to climbing trees than their brethren, and insects that may grow large enough to fulfill the role of birds.
A neat example of this (used by DNA in 'Last Chance to See) is the Kakapo - a ground dwelling parrot which fills the niche of the rabbit in a country devoid of them. This is where we witness rapid speciation - as animals adapt to new niches.

I suppose there's also the issue of puntuated preservation to be considered. Even if things *were* smoothly varying, the irregular sampling of irregularly preserved animal and plant remains could still result in a rather patchy record.

Bear with me here, but the magnetic pole shift also causes the earth's axis, which is tilted ever so slightly, to tilt the other way, if I remember correctly. Now, even the smallest change in the earth's axial position can result in major climactic change, and thus, a changing axis would, by extension, create a different climate (i.e., the ice ages). This would not be a rapid change per se, but certainly would affect the adaptability of species.

The earth's axial tilt is approx 23 degrees, which is responsible for the seasons. Although it wobbles slightly it doesn't change direction. The magnetic poles do not correspond to the axial poles, the magnetic field being generated by the solid iron core of the planet.

Noggin

The inner core is solid (as is presently understoof), the outer core is liquid iron. If you're interested they think they may have detected another core within the core...
http://news.bbc.co.uk/1/hi/sci/tech/2290551.stm

Yes, yes, yes. I know all that. I'm gong to see if I can unearth this dim memory....I know that somehow the magnetic pole shift did something to the axis or perhaps the rotation....back soon!

Woodpigeon: As far as I am aware, the rate of mutation is not affected. Actually, I'm certain the rate of mutation per se is not affected, though possibly at certain times it is easier for mutations to become established in the gene pool (so the apparent rate of mutation might be greater). This would happen during 'easy' periods, though dramatic changes in the morphology of the world population (that we would recognise as the appearance of a new species in the fossil record) would occur only when the newly-well-adapted creatures fill the large vacancies left by the newly-extinct critters during 'hard' times.

It seems that this understanding of evolution should predict that mass extinctions coincide with (or narrowly preceed) periods of rapid evolution. The 65MYa dinosaur extinction / mammal apearance event would be one such example, but does anyone know how other mass extinctions correlate? Given that we are living through a period of mass extinction, should we expect to see radically new life appear on the planet over the next million years or so?

Montana: The Earth's tilt and spin may cause the chaotic effects in the liquid core that in turn cause the changes in the magnetic field, but I'd be surprised if the reverse is true. (Which is not to say that I know for sure it's impossible ...)

Gif