intelligent design bashing is getting old...

[Crayfish]

Yikes, lots of questions. While I could answer most of them, it'd take a book. I suggest that if you are really curious about these things, get a good book on evolution.

The basic ideas of evolution and natural selection (A. there are heritable units which copy with occasional mistakes to produce a range of similar variants; B. those units which are best suited to the organisms' environment tend to increase in frequency) are simple, but their connotations and applications are really complex, especially seeing as we have to essentially reverse engineer to understand them case by case.

For this reason, the questions

Where do eyes come from? The liver, the heart, the immune system, the kidneys, the lungs...

each require a quite lengthy answer. The underlying mechanisms will share themes, but the specific story of how each one developed through a series of useful 'prototypes' is just, long.

For now, I'll focus on the eye.

The human eye, at first glance, appears so complex that unless it was created whole, each part would be useless - what would you do with a lens on its own? An eye requires a number of basic structures to function - a retina with photopigments that respond to light, a lens to focus light, and a few other less essential but useful features such as a pupil to regulate light intensity.

Now, while a lens isn't much good on its own, a light sensitive 'retina' may just be. Light receptive spots (using similar photopigments to our eye) can be seen in many living organisms today e.g. daphnia. These simpler structures lack a lens or pupil but are still useful - even if (in the simplest eyespots) they can only be said to detect the amount of light present, this can still inform an organism whether it is day or night, and whether they are in shadow.

The next step in our process operates on the principle of a pinhole camera. This requires the eyespot to become recessed into a pit or chamber, with a constricted opening. This arrangement offers the functional advantages of directional sensation, and some gross shape detection. A living example is the eye of the[url=http://en.wikipedia.org/wiki/Image:Nautilus.jpg]Nautilus[/quote], which due to a very stable environment is thought to have undergone little modification for the last 500 million years or so.

From here, the advantage of developing a lens can clearly be seen. In fact, even developing a lens with 10% efficiency would be an advantage - there's no requirement for one quite as technically refined as ours to spring into being. This can occur as the transparent cells covering the pinhole aperture split and fill with liquid, followed by the development of a refractive protein (e.g. crystallin in humans), followed by the efficient localisation of this protein, followed by the development of focussing devices (muscles which pull on the lens). Or some order such as that.

As far as I know, there aren't good living examples of these last few incremental intermediates and soft tissues such as eyes don't tend to preserve in fossils, but it serves as an illustration of how each 'prototype' eye is progressively more useful, with only one part of it needing to alter at any given stage.

See my next post for a more general overview.

[LordMatt]

The entire process of going from "no eyes" to "eyes" must take millllllions of years. During that whole time the animal just keeps on developing them. They're useless the whole time. Totally useless.

Wrong. Even half formed eyes gave those that had them some advantage over no eyes. A few individuals developed slightly better eyes, and had a slight advantage over the rest of their kind, and therefore their traits became more prevalent and so on.

In my opinion, "pure" evolutionists haven't got a lot to look forward to - whether they die by disease, old age, as punishment for crime, or some god's wrath, they're going to die. "pure" creationists, reasonable or informed or not, believe they might live again.

If they see the truth of the world they live in, and live their lives accordingly, is that not better?

[Crayfish]

Okay, following on from my previous post and continuing to answer some of the (good) questions asked here.

Why are such obviously inefficient things developed? Myself I think it would be benficial to be able to breathe and eat at the same time.

As we can see from the stages of development of the eye, evolution works best when it can change just one thing at a time. For a gene to randomly arise to hit just the right code to produce a protein with just the right function is difficult, to expect 200 genes to simultaneously do this is unlikely to the point where it may never occur even in 3 billion years.

A semi-mathematical way to look at this is, imagine the chances of taking a random number generator and trying to hit the simple sequence 4058366289. The chances of getting this exact number (limiting to a maximum of 10 digits) are 1 in 10,000,000,000. This is concievable in evolutionary terms given the timescales involved, but genes average around 2500 'digits' rather than 10 (albeit being base 4 rather than base 10).

Luckily, evolution keeps features that work. Imagine now that you can take that same random number generator and each time you run it, if one digit is the right number in the right place, you keep it. So if you get 8236432469, you can keep the 9 at the end. Keep doing this, and each time you get a number right your chances improve, and you'll have to run the number generator much fewer times to get the same end result.

Bear in mind that just like we saw for the eye, partial genes / proteins are sometimes useful (or one particular part of them is the most useful bit, the rest being refining but not essential features).

Now, to answer Caydr's question about inefficiency: these processes are inherently random, with no 'aims' or 'directions'. The genes don't think 'it'd be nice if we could make some lungs today, but hey, let's make it so that we can also eat while breathing'.

Building things up part by part, each new feature being evolved in a random (but selected for) fashion, means that sometimes the established features create inefficiencies for the new ones.

A complete reworking of the system may be better, but by the time that you've already got a mouth maybe it's easier (therefore has more chance of happening through the random processes of genetic variation) to also use that to take in air.

Incidentally, this is a good argument against intelligent design - there are so many of these inefficient features that could be designed better intelligently that it suggests there was no conscious design (or that the designer wasn't actually very good).

In other species, there are more efficient versions of several organs, but they follow different evolutionary paths. You can see that if one step at a fairly basal level in the development of an organ takes a different tack, subsequent changes will be based on that and could produce a quite different system. See for example the avian respiratory system and the octopus eye.

Why are even the strongest humans essentially defenseless against animals unless we're armed? Shouldn't we be stronger? For the whole of human history being strong was regarded as a good thing, and at least for recorded history up until maybe a hundred years ago, people had to work REALLY HARD just to stay alive! So according to the idea that people have been around for millions of years, we should be freaking badasses, hammering nails with our bare hands! Even WITH tools the stronger you are the more effective you'll be and the more likely to survive. The people with the best "upper body strength" genes should be the most likely to survive, so why are we completely pathetic compared to chimpanzees?

This one's a little more obscure and speculative, but it still makes sense. The main piece of evidence for this is from comparisons of gene sequences between ourselves and other apes. We find that one gene that stands out is that encoding myosin, an important constituent of muscle. In humans, mutations have occured to make myosin protein much less efficient than in other apes, and an estimate (from comparing similarity in more closely and less closely related apes) of when this occured places it at about 2.6 million years ago.

One other major difference between ourselves and apes lies in the skull. Largely because of the difference in the myosin gene, apes have bigger, stronger muscles than we do. The jaw muscles are particularly large, and require strong, bony skulls to serve as stable points of attachment for these muscles (without them ripping the skull apart by their action).

Humans on the other hand, have less bony skulls and smaller jaws, with the space that is freed up by this change being filled with brain. This accounts for the larger brain-body ratio of humans compared to other apes. It may have been that the brain started to increase in size, but couldn't progress further until this myosin mutation appeared. What selective advantage this could initially have offered, I'm not sure. Once spears and so on come in, the requirement for muscles to compete with other animals is reduced, but 2.6 million years is long before spears.

Incidentally, although a strong person will be more efficient with a spear, 'good enough' is all that is required by natural selection - particularly bearing in mind that large muscles require more energy to form and maintain, and require other structural changes such as to the skeletal system as mentioned. For an omnivore who doesn't necessarily need to tackle animals too often, being able to survive on less food could be more of an advantage than being able to strangle a mammoth or whatever. May also make childbirth more difficult.

I realise this isn't a completely satisfying answer, but that's as much as I know. There may be research that I'm unaware of, or it may just be a question that still needs answering better.

Typed too much now and don't want to take over the board. Macroevolution and punctuated equilibria later.

[Teutooni]

INCOMING WALL OF TEXT, GET THE F**K DOWN!

OH SHI-

[PicassoCT]

INCOMING WALL OF TEXT, GET THE F**K DOWN!

OH SHI-

Completely wrong Attitude - just see it as Texttetris - once you have the whole Wall filled - the Tab will disappear..

P.U.R.E. Win (and besides always a good Advertisement Strategy to have a Mod/Game named after a reappearing Word) so lets see the Discussion Creationsm vers Evolution out of both Perspectives. In one Go(o)dReason created both to Bitchfight each other to the End of Days- so that the Believers won´t have a good day on earth. And from evolutionist eye-persepective the one wasting the smallest amount of time in discussions with blind believers, producing well-educated offspring meanwhile will win the discussion. No Idea why they talk with each other.... One doesen´t care about proof, the other one over believe, so they are in completely seperated worlds..

[Dash_Riprock]

If they see the truth of the world they live in, and live their lives accordingly, is that not better?

Here's something to think about- If God doesn't exist, then neither can free will. Without some outside force (soul) influencing the physical world on some level, than every single action someone takes is just the result of certain interactions of atoms in the body. So basically, I was guaranteed to be typing this exact message right this exact instant, and am in no way better than Jeffrey Dahmer, who was guaranteed to have murdered 17 people because of the arrangement of cells in head, which took certain inputs and resulted in a certain output. So, basically the statement that you are an atheist and you choose to do something is inherently flawed.

This is really the main reason that I would prefer that there is a God, though at this point in my life I haven't seen any good enough reason to rule out either possibility.

[Crayfish]

What you're talking about is the idea of determinism. That's hardcore quantum physics and outside of my area, but I know that another prevailing theory holds that all events are essentially random (e.g. at the smallest quantum level, particular interactions are truly, fundamentally random - rather than the characteristics of said particles leading to a set course of events that could be no other way).

On the other hand, as we haven't managed to find this irreducible quantum level yet and would have absolutely no way of modelling events from that scale even if we found it, even if events originating at this level were completely deterministic and predictable in nature, they would still appear random on any level that we can possibly sense or measure. So it wouldn't matter.

[Peet]

Even if our actions (and our considerations of these actions) are 100% predetermined by the state of the universe, it still feels like we're making our own decisions...that's what matters imo

[The_Big_Boss]

We dont really understand how a gene works anyway. Since the facts and knowledge about genes continues to change, any assessment on evolution is just a guesstimate. Is it possible for an ape to change into a man in a given time? It depends on all the factors, not just the ones man discovers. Look at this link here. This is new, this is recent.

http://www.sciencedaily.com/releases/20 ... 193819.htm

[Teutooni]

it still feels like we're making our own decisions...that's what matters imo

+1

[Crayfish]

We dont really understand how a gene works anyway. Since the facts and knowledge about genes continues to change, any assessment on evolution is just a guesstimate. Is it possible for an ape to change into a man in a given time? It depends on all the factors, not just the ones man discovers. Look at this link here. This is new, this is recent.

http://www.sciencedaily.com/releases/20 ... 193819.htm

Interesting link. Doesn't seem to have a lot to do with evolution though, unless you could explain why it's relevant?

The products of evolution (genes, organisms) are very complicated, but the mechanisms of evolution (heritability, selection) are simple and well understood.

Also, apes never changed into humans, stop that. We share common ancestors and equally evolved from that point, quirks of chance and the environment just mean that we took a unique direction.

[LordMatt]

Here's something to think about- If God doesn't exist, then neither can free will. Without some outside force (soul) influencing the physical world on some level, than every single action someone takes is just the result of certain interactions of atoms in the body. So basically, I was guaranteed to be typing this exact message right this exact instant, and am in no way better than Jeffrey Dahmer, who was guaranteed to have murdered 17 people because of the arrangement of cells in head, which took certain inputs and resulted in a certain output. So, basically the statement that you are an atheist and you choose to do something is inherently flawed.

This is really the main reason that I would prefer that there is a God, though at this point in my life I haven't seen any good enough reason to rule out either possibility.

The people who say "if there isn't a God it's okay to rape and murder," or some variation of that scare me the most. Are they really serious? I don't rape and murder, not because I am afraid of the wrath of God, but because I have no desire to do that.

Free will is an interesting topic, one that is under intensive research with neuroimaging now. It has been shown that our brain's neurons begin to fire often several hundred milliseconds before we perceive ourselves making a decision. In fact, it appears that rather than "free will" we have something more like "free won't," where the last decision in cognitive processing is whether or not to inhibit some planned behavior based on judgments about what is good for the individual and how it will be perceived by society. In fact, it is possible to lose what we think of as "free will" as a result of brain injury. Do a Google search of Phineas Gage for the most famous example, though others with similar brain damage have the same symptoms.

We dont really understand how a gene works anyway. Since the facts and knowledge about genes continues to change, any assessment on evolution is just a guesstimate.

We? More like you don't understand how they work. No one working in that field would share the opinion you just expressed there, no one. Science is mankind's best answer to any particular question (except perhaps one), the answer may improve over time as more details are made clear, but for something as well supported as evolution, the principle will not change (see such principles as the earth revolves around the sun, something that was the cause of imprisonment for some early scientists, because it contradicted religious teaching, but is now accepted by basically everyone).

[BlueTemplar]

Stop bashing intelligent designs! I think that Mr D's core designs are great!

[The_Big_Boss]

Interesting link. Doesn't seem to have a lot to do with evolution though, unless you could explain why it's relevant?

The products of evolution (genes, organisms) are very complicated, but the mechanisms of evolution (heritability, selection) are simple and well understood.

I think you said this out of order, because in order for me to answer it I have to address the second paragraph first, which is kinda annoying honestly.

The general argument of evolution doesn't just fall under the lines of heritability and selection does it? Because to me they dont. Telling me how to put legos together, or how to grab legos out of the bin, or which ones could be grabbed, doesnt actually attribute to architecture directly, though its safe to say it does have some effect. If i cant grab large blue legos, simply because that opportunity has been denied, then obviously my structure wont comprise of those. Is this not true?

Also, apes never changed into humans, stop that. We share common ancestors and equally evolved from that point, quirks of chance and the environment just mean that we took a unique direction.

Sorry, your right. I spoke 'slang'. But, on a side note, and I find this quiet interesting, cant we manipulate apes into humans if given enough tries? What would happen if dogs were manipulated and gained intelligence, how would they look and judge human beings? (Surely you dont need to look human, to communicate like one?)

We? More like you don't understand how they work. No one working in that field would share the opinion you just expressed there, no one. Science is mankind's best answer to any particular question (except perhaps one), the answer may improve over time as more details are made clear, but for something as well supported as evolution, the principle will not change (see such principles as the earth revolves around the sun, something that was the cause of imprisonment for some early scientists, because it contradicted religious teaching, but is now accepted by basically everyone).

I'll take your point to another thread if you wish (:

[SwiftSpear]

I think most Christians and even creationists will get on board with evolution these days. There's just overwhelming evidence that it exists. The problem for most creationists is natural selection. There just isn't alot of evidence to support it as the only, or even the primary, method of evolutionary direction. Of course for the creationists, this is great, they just say "Obviously God did it!".

Even if you choose not to be so ignorant though... fossil evidence, recent evolutionary experimentation, and even just the current distribution of species, leave a lot of questions as to how exactly evolutionary advancements work. Natural selection seems sensible, but there is just no evidence to support it.

[tombom]

Even if you choose not to be so ignorant though... fossil evidence, recent evolutionary experimentation, and even just the current distribution of species, leave a lot of questions as to how exactly evolutionary advancements work. Natural selection seems sensible, but there is just no evidence to support it.

Except all the fossil evidence, all the scientific tests, the behaviour of diseases etc

[Crayfish]

I think most Christians and even creationists will get on board with evolution these days. There's just overwhelming evidence that it exists. The problem for most creationists is natural selection. There just isn't alot of evidence to support it as the only, or even the primary, method of evolutionary direction. Of course for the creationists, this is great, they just say "Obviously God did it!".

Even if you choose not to be so ignorant though... fossil evidence, recent evolutionary experimentation, and even just the current distribution of species, leave a lot of questions as to how exactly evolutionary advancements work. Natural selection seems sensible, but there is just no evidence to support it.

Well... there's the evidence that applying selective pressures alter allelic frequencies in a population. See MRSA / C.difficile for prominent examples. There is also plenty of evidence to suggest the formation of new genes and alleles.

There is also the phenomenon of artificial selection in most domestic animals, where humans have used the principles of natural selection but applied artificial selective pressures by controlling breeding.

A variety of similar observations are reproducible in laboratory conditions in microorganisms / flies and in field conditions for longer lived organisms. I'd have said there was quite a wealth of evidence. Maybe I'm not attaching the exact same meaning to natural selection as you? Not sure.

[erasmus]

wow...kudos to crayfish (also tombom, teutooni, kdr) for answering questions very thoroughly and addressing many fallacies in the understanding of evolution


caydr,
evolution is not a series of random events
evolution is actually highly directed, at least by the mechanism of natural selection
what is "random" though is the genetic variation in a population present due to mutations and the resulting phenotypic variation, and that is what natural selection acts on


about the evolution of the eye, you are raising the question of irreducible complexity
there is an incredible wealth of research out there for your perusal concerning evidence of evolution, and just because you are not in this field and do not have the answers for certain questions doesn't mean you can dismiss their findings (Argument from ignorance)

in fact, a lot of research in this field right now is trying to discover the intermediate evolutionary stages for highly complex adaptations such as the eye



also, evolution cannot "have a goal"
natural selection does not set out to create the "best" species....what it does is it gradually weeds out those individuals that are less adapted to the environment and thus less capable of survival, leaving behind a collectively more adapted species

evolution does not lead to perfection either
everything is energetically costly... therefore, an evolved organism is kind of a tradeoff or compromise between costs and benefits
that's why not all animals possess all beneficial traits... species are suited to specific niches because it is efficient

sure it'd be awesome if we all were freakin superheroes with wings and awesome upper body strength, but if that meant every child required 30 years to grow up instead of 16 or that a mother could bear only a single child in her lifetime or that we would need to eat a truckload of food a day to support ourselves, do you think our species would be successful? nature says no, nature says that our current state is the best compromise


anyways... a huge amount of our new knowledge and breakthroughs in biology is all thanks to our modern understanding of evolution
so just from a practical standpoint, evolution > creationism

like the guy in the video said, modern biology would not make sense without evolution

[Panda]

I like looking through the biology information available in this discussion. You can't learn everything through books.

My contribution, the purpose of the genome project is to determine what makes humans distinct from other species.

Is this a Creationist/Evolutionist/Neither? perspective on axolotls. The Axolotl was made by a creative force which determined that it would be a salamander that had a 3 chambered heart, lungs, gills, vestigial teeth, looks like a fish with legs, and is not to be confused with water dogs or mudpuppies.

Also, why is it that so many other animals don't sweat as much as humans do? Apes don't sweat as much as humans do, but horses do.

[tombom]

Sweating is a cooling system; I imagine mammals which don't sweat much just don't need to.

The axolotl is just a salamander which never moves out of its larval form. If you look at baby salamander they all look pretty similar, it's not unusual. At some point in the past they got a mutant gene which meant that they didn't produce the hormone that causes the metamorphosis. It can still be induced through giving it to them. The teeth would usually develop during metamorphosis but because they never went through it only vestigal bits are left. Pretty much all their differences can be ascribed to this.

Axolotls are also one of the cutest animals SCIENTIFIC FACT