US school's new challenge to Darwin

That was a very good read, thank you for bringing it to my attention. It's well past midnight here, so I'll try to answer in the morning.

And the Global Warming thing was just my poor attempt at a pun. I was trying to avoid a flame war, and thus, reduce heat output into the environment.

 

Nope, sorry. We know for a fact that before gender was introduced, all lifeforms were self-reproducing (logically). Then, at some point, we got hermaphrodites (e.g. snails), who could self-reproduce but had the added advantage of being able to exchange genes by mating. Then certain members of the species remained reproductive (arbitrarily labeled "female"), while others lost that ability and became pure gene (sperm) donors (arbitrarily labeled "male"). You see this in both plants and animals. The evolutionary advantage of this arrangement is discussed in my previous post.

Now if we follow your logic, if God created man first, then men would have no nipples at all --after all they were an added extra for women, where they have a distinct function.

As Matkubiki said, we enjoy sex because a strong sexual drive is an evolutionary advantage --it makes your species want to procreate even when conditions are pretty harsh. Look at some Third World countries: there may be famine, disease, war, but people keep breeding like, well, rabbits, which follow the same principle. Over here, we would too of course, but we have access to birth control that allows us to endulge our biological drives without the unwanted consequences (artificial sweeteners and low-fat foods exist for the same reason. ). This, incidentally, is why it is so difficult to keep teenagers celibate until their psychological maturity has caught up with their sexual maturity. Sex is wired into the brain as a basic drive, as natural and compulsive as eating and breathing.

We are not unique in that; other animals enjoy sex too. The Bonobo chimps in particular, use it for relationship building, not just for procreation (like us). Dolphins turn out to have a high sex drive, and many animals will happily beat each others' brains in, in competition for a mate... and we all know that a dog or rabbit will pretty much hump anything.

We have. In particular the Flagella, flagship of ID, has been demonstrated to be a product of evolutionary processes, with clear intermediate stages still existing all over in nature. But I see Malf has beaten me to it with a link.

And dude, what we defend against we create... the best way to guarantee flaming is to tell someone that they are. We're all cool here.

 

Allright, a quick rebuttal to the article linked. Please bear with me, it's been a few years since Bio.

In the essay, there are four ways in which the author proposes that an Irreducibly Complex (IC) system may have evolved:

* Previously using more parts than necessary for the function.
* The parts themselves evolve.
* Deployment of parts (gene regulation) evolves.
* New parts are created (gene duplication) and may then evolve.

His first suggestion, while possible for some things, simply can't cover others. Say, the first living cell. It simply isn't an option, as there was nothing beforehand that was more complex to become it.

His second suggestion is rather improbable. It claims, basically, that all the parts needed could evolve seperatley, and then come together in just the right way to create something that is favored by Natural Selection, which then evolves into an IC system. A brief analogy: What are the odds that randomly cut and drilled peices of wood, randomly stiched and cut bits of cloth, randomly machined parts of metal, and a whole pile of random bolts and fasteners could happen to be tossed together in such a way as to create an airplane? While yes, given enough time, it is possible, Evolution really can only go back so far, before it starts to run into cosmic problems. Such as, say, the contraction of the sun.

Argument the third: He also argues that genetics can change, and thus, the protiens they create change as well. While this obviously can happen, it is very unlikely that it will do anything favorable. Even if it does, it's just one change. To get from one IC system to another would take thousands of favorable changes, each one of which must be better than the one before it. He says that "When a protein is deployed out of its usual context, it may be co-opted for a different function." Probability strikes again. The odds of a randomly-generated protein interacting with a randomly chosen system to create a better system are remarkably low. First off, the system needs to have a spot for the protein to come in to. Then, the protein needs to actually fit. Then, the entire expanded system needs to actually be able to do something useful. Odds? Rather slim.

And then, there's the fourth option: genetic duplication. This is, simply enough, the argument that a gene could get itself copied, so two proteins are produced instead of one. Then, both of the duplicate genes mutate, in different directions. Soon, instead of two identical proteins, there are two different proteins that rely on each other to work correctly.

It's the revenge of probability, I'm afraid. Once again, all the mutations have to happen in the right way, at the right place, at the right time. The odds that hundreds, or even thousands of them could happen, precisely as needed? Remarkably low.

As an IC system, I would propose a living cell. Remove any of its components (cell wall, mitachondria, flagellum, nucleus, and vacuoles, to name all that I can think of), and the cell stops working. Ignoring the first option (it's a cheap escape from situations like this), how could a cell come into existance?

 

Here is where we hit concepts such as reiteration, non-linear dynamics, Critical Dependence on Initial Conditions, Emergence and suchlike... Bear with me...

First, you are proposing the wrong mechanism for the wrong phenomenon. "Previously using more parts than necessary for the function" does not work for cells, because it does not apply to cells. Cells are a product of accumulative and exponential evolution. However it does apply in other ways. There is selective advantage in efficiency because there is less to go wrong. But there are other reasons also: some cave-dwelling fish, insects and amphibians for instance have lost their eyes, because in the absence of an advantage (i.e. to be able to see your environment) to outweigh it, they have become a big disadvantage in an environment where bioluminescence is a common trick to lure prey.

Onto: "The parts themselves evolve". Single-cell lifeforms, especially at a bacterial level, produce new generations very fast (every 20 minutes), and do so not only by the billions, but also exponentially. Start with one little blighter, and in one day (72 generations) you have 2361 billion-billion of them. And they don't take up much space --you can fit all of them comfortably on a post stamp. Now wait another day (144 generations), and you have <buffer overflow> bacteria... Now wait a few million years... got the picture? Plenty of opportunity for random chance to result in a few tweaks.

The reason why you can't see apparently random mutations resulting in something with the same level of sophistication as an airplane is because you are not considering the sheer exponential number of reproductive trials and the accumulative effect of mutations in that exponential context, each building on a previous successful mutation, again and again, with constant selective forces brought to bear on every generation (reiteration).

Rather like we created airliners by messing about with kites and falling to our death in interesting contraptions for hundreds of years, before getting to the Wright Brother's simple wood, bolts and cloth constrution flying 100 yards, to Biplanes, then Dakota's, then Boeing 747s and then Stealth Fighters in a comparatively short time afterwards, life messed about for millions of years with simple pro-kariotic single-cell life forms and then blammo! The whole thing takes off exponentially and cumulatively.

The story doesn't end there though. It is a common phenomenon that when systems attain a certain level of complexity, they all of a sudden start exhibiting new properties that weren't present before. If those properties convey any selective advantage at all, they get passed on. Mutations occur, of course, and selective forces again are brought to bear on them, which (accumulatively) can give rise to more or different complexity, more emergence, and so on and so on (again, re-iteratively). The more complex the system, the more room for new variety and new emergence.

"Deployment of parts (gene regulation) evolves". Again you argue about probablility and chance. Same as above: exponentiality, and accumulation, reiteration and emergence.

Another idea to consider: simple rules can give rise to extremely complex and unpredictable behaviour. Consider a chess game. A finite board with 64 positions, and 32 pieces, each of which can move in only a very limited number of ways. Yet we all know chess is an immensely complex game, and I doubt that all possible combinations of moves will ever be made (another example could be a program called "Langtson's Ant", but I'll leave you to consider that one for now...). So a short, simple sequence of genes, with simple "rules" on how they affect protein sequencing, can underpin complex interactive cellular processes and constructs indeed.

"New parts are created (gene duplication) and may then evolve". This process is much simpler than you think. The same gene can give rise to two quite different(ly functioning) proteins; it is a matter of how they fold. The probem for cells is that when DNA (or rather, RNA) is transcribed into proteins in the ribosomes, these proteins sometimes have an annoying habit of folding the wrong way. In order to correct that, cells use prions (yes, from Mad Cow Disease fame) which are tough proteins that sort of "shoehorn" the errant protein into its correct shape. Prions don't rely on DNA for procreation; they use themselves as templates for reproduction (The prions in Bovine CJD are mutations that happen to go around shoehorning certain proteins in the CNS into shapes that are 1. copies of the prions themselves, but also 2. harmful to the proper functioning of the CNS). Prions probably existed outside of (and before) cells, but they were sort of co-opted in the cellular process, a bit like mytochondriae were.

The problem with your example of a cell as IC system is that you reason in the wrong direction, and also decide to take away big chunks of it at a time. However you can probably take away about 90% of a cell's DNA and it will happily continue to function (or, as recently demonstrated in the case of a fertilised egg cell, even grow into a healthy lab mouse). As i said before, most DNA is legacy... However we can see plenty of examples of singe-cell "life" that doesn't have any of the components you mention: virusses. Just a vessicle with some RNA --that's it. There are the prokariotes --cells that have no nucleus whatsoever. And although cells cannot survive without mytochondriae, mytochondriae themselves manage quite well without the rest of the cell.

 

Erm... no, tbh.

We are not looking at the first living cell. If we could then the argument for IC/ID/Evolution would be a lot lot easier.

What we can look at (and we do), is a single cell organism in a world filled with many cells that have survived before and will continue to strive after.

And withen these single celled organisms, evolution as been observed.

Maybe you would call that a 1-in-a-million chance? maybe even a 1-in-a-billion chance? Well, what ever it is, it is still a chance. If you were to say there was a 0 chance, then your argument would hold water. As it is, even the smallest of chances remains a door of oppurtunity.

They say that to win the national Lottery is a few million to one afaik, well.. people seem to win it quite frequently some weeks, and sometimes nobody wins for weeks at a time.

As long as there is a chance, however small, there is way. Just because the probability is too small for some people to comprehend, doesn't mean it is not possible.

same as above, just because you find it unlikely, doesn't mean it's impossible.

change can happen for good or for bad... the bad get discarded, the good move forward. the ones that did not change remain indifferent until there comes a point in time where the changes for good out number the indifferent and that's called natural selection.

that's the thing you guys tend to see it as... ít happened at the right time, place, right way'.... it was never explained like that.

It could have failed on numerous occassions, faultered, changed paths more than once... just because you only see one snap shot on the process (i.e. us) doesn't mean that there was a straight line in which everything happened... branches occured.. one branched mutated in a different way to the others, that way happened to be better... then that group also branched off and some branches mutated and did one fair well... some branches mutated and benefitted, some remained the same.

then all of those also branched off, some remained the same, some mutated, some benefitted, some didn't..

and... so on a so forth.

it didn't just mutated straight away to a better complex organism, and then mutated in the right way again, and again.

 

Good point. The name for this reasoning trap is "the anthropic principle". We marvel at how things in the Universe turned out to be just so that it gave rise to us, and the infinitessimal probability of it. But we can only do so because we happen to be here to do so. It might (or may) so easily have turned out very differently on innumberable occasions, but then we wouldn't have been there (or weren't) to know about it.

It is like marvelling at the probabilities of your parents meeting to produce you. They did, so you're here to marvel about it. But they could just as easily not have, and then you wouldn't have been here to know they didn't.

 

Thats a very good point and one that i love to mull over. People saying, "what if the earth was a tiny percentage closer to the sun, then none of this would have happened." But in our current situation (or even dimension if you like such ideas) the probabilty of it being placed here is 1. If it were somewhere else we wouldnt be here but maybe something else would thinking the same things.

 

FACTS:
1) 10 million years ago sky-octopi were the top level predators. No one knows about this because they were too squishy to leave fossils.
2) sky-octopi are resposible for 90% of things that have evolved. We only have opposeable thumbs because our monkey ancestors used them for gouging sky-octopus eyes.

 

You really do your name justice, don't you?

 

I thought this thread had died violent painful fiery death....

 

It should have...

 

Ideoteque,

Wow, I didn't know that this scientific fact was so widely known. However, they were actually sky-squid and not occies and secondly your thumbs might be related to whichever species of monkey you wish, but I have no such relatives. Keep up the worthy research and provide regular reports of your findings.

Touchwood.

 

(i'm assuming you mean that you don't come from a common ancestor as apes)

explain why you look so similar to one (not insulting). you both have similar hand structure, some people are even as hairy as apes; you walk in a similar manner (some species); and you would also fight to the death to protect your young.

not to mention that you share some insane percentage of identical DNA as an ape. i'm not saying that somewhere way back in the day your granpappy did the nasty with an ape, but it's essentially assured that if you went far back enough, the ape and you would have a common ancestor. you're like cousins.

 

Amazing, just like Darwin!!!

Thanks for the input, but I did not see any while at Llanfairpwllgwyngyllgogerychwyrndrobwllllantysiliogogogoch.

Touchwood

 

did your cat run across the keyboard?

 

Cats and Keyboards, what an interesting DNA mutation assumption. But alas no dear I'm_Not_A_Monster, tis nought but a location in Wales.

Dymuniadau gorau,
Touchwood.

 

Closing this thread, seeing as all attempts at serious discussion are being waylaid in Wales or eaten by sky-octopi...