I had a hard time understanding anything this thread was meant to ask, and I can't help but feel that that's not my fault.

Zadocfish2 wrote:I had a hard time understanding anything this thread was meant to ask, and I can't help but feel that that's not my fault.

First of all, whilst some of the concepts involved in evolutionary biology are elementary, others most assuredly aren't. Part of the problem here, is that concepts from both parts of the spectrum have appeared during the discussion.

Most people are aware of the elementary concepts involved in evolution, of which the most elementary is that the genes you inherit have a major impact on what you are. Another elementary concept, backed by vast mountains of data, is that between generations, some of those genes can change. Specifically, mutations can occur in the genes located within germ cells, which are the cells responsible for generating sperm and ova. Mutations in those genes are the mutations that are passed on to future generations, if the requisite sperm and ova meet.

Now, the next question to ask, is what forces act to maintain those mutations within a population. Mutations that kill their inheritors before reproductive age are obviously not maintained, and this likewise applies to mutations that result in reproductive sterility. This leaves a lot of other mutations, that don't kill, sterilise or cripple their inheritors.

The first mechanism for preserving such mutations in a population was, of course, the one Darwin put forward - selection. Understanding selection is pretty elementary. If a new mutation bestows additional prowess upon its inheritors, allowing them to leave behind more offspring, then those mutations will not only be maintained in a population, but pretty soon start to become increasingly prevalent within that population. Doesn't take a rocket scientist to understand this.

However, selection isn't the only possibility. It took scientists a little while to accommodate this idea, because it wasn't obvious how other possibilities could work, but thanks to people such as Motoo Kimura, we now have in place what is known as "neutral drift", which centres upon the fact that the majority of mutations don't actually result in significant change in reproductive prowess. Yet, these can persist too. You're currently carrying something like a hundred of them that you inherited from your parents in your genome, and you in turn will probably pass a hundred new ones to your offspring. Some of the mutations in this class will perhaps only last for one generation, before disappearing, whilst others will last for 10 or even 100 generations, and some may even be more persistent than that. Lenski's landmark experiment provides us with the evidence for this.

Basically, every population carries around with it, its own collection of neutral, or approximately neutral, mutations. Some of which persist long enough to have something interesting happen to them. Namely, they become the substrate from which interesting new non-neutral mutations can arise. Classic examples include the Cit+ mutation in Lenski's experiment, which only arose after a collection of neutral mutations arose within the requisite population from which the new Cit+ mutation could arise - a nice, rigorous demonstration of the power of historical contingency. Another example is the antifreeze glycoprotein mutation in Antarctic Notothenioid fishes, which arose when a trypsinogen gene underwent duplication in that lineage. The duplicate gene was free to accumulate mutations without interfering with the metabolism of the fishes, whose other copy of the trypsinogen gene continued functioning in the usual manner whilst the duplicate was roaming its way through mutation space. Somewhere along the line, the mutated duplicate copy started coding for an interesting new protein, which suddenly bestowed upon those fishes inheriting this a new ability - namely, the ability to move into Antarctic waters and start feeding on new food sources, without the less than happy consequences that befall other fishes sticking around too long in the Antarctic winter, whose blood freezes solid. This new protein acted as an antifreeze in the blood of the Notothenioids, and they were able to remain in Antarctic waters through the winter, thus setting up permanent home in a nice new habitat with food sources inaccessible to other fish competitors.

That's an important point to remember - neutral mutations can form the seed material for something later on that becomes selectable.

But another point to remember, is that what benefits the population doesn't always benefit individuals in that population, as far as genetic legacy is concerned. The Sickle Cell miutation is a case in point. Any individual unfortunate enough to be homozygous for this (i.e., inherits two copies of the gene, one from each parent) is going to lead a miserable life. Which makes you wonder why this mutation persists. Well, it so happens that being heterozygous for this mutation, namely inheriting one copy of the gene, doesn't lead to you having a miserable life afflicted by disease. On the contrary, it actually offers enhanced resistance to something nasty, in the form of malaria parasites. Those homozygous individuals with unfortunate disease symptoms, are the price the human population paid in the past for having a bigger proportion enjoy enhanced protection from malaria.

So, quite simply, a gene can be beneficial to a population, but have a downside for some of the individuals in that population.

And this, quite simply, is what happens in the case of several documented instances of homosexual behaviour. Because male individuals who keep company with the females, but don't constantly pressure them for sex, can be of immense benefit to those females, especially if they're good at something else, be it vigilance against predation or assisting with the rearing of offspring. A female organism that would only rear two or three offspring in her lifetime in the exclusive presence of the typical rutting males, but who ends up rearing seven or eight with the assistance of a male that's out of the rutting loop, is going to leave a bigger genetic legacy behind her. Indeed, in species where social rearing of offspring is advantageous, it's entirely possible that 'out of the rutting loop' males are a big plus. And, if those 'out of the rutting loop' males also divert some of the rutting attention of, shall we say, less than optimal rutting males, then again, the population wins, even though a fair few individuals lose out from the reproductive standpoint.

That's the key point. Evolution is a mechanism for maintaining populations, and is completely indifferent to individuals.

Though as it happens, some of those instances in insects can also benefit certain individuals too. Xylocoris maculipennis is an example of one of those insects, in which homosexual copulation is documented. It's been determined that in this instance, the receiving males solicit the attention of other males, for the express purpose of decommissioning those other males' genitalia for a while, leaving the receiving males to go on and mate with the females. Sneaky, huh?

My approach to evolution is as follows.

Science has established that evolution is a fact.
This fact is supported by a great deal of evidence in its favour.
In support of it as well, is that as a principle, it works‡.
Specific attempts have been made to discredit evolution, but have all failed.
Evolution remains the only credible scientific explanation for the current state of life on earth.
If something is found in nature, (including human nature), then it is rooted in evolution.
To simply say that, is circular, if the aim is to show that evolution is true.
On the other hand, to simply say that, is to use the Theory as it stands.
It is not enough on its own, to simply say that: 'if something is found in nature, then it is rooted in evolution'.
It must be investigated, and shown how it can rooted in evolution, (what steps of progression can lead to the extant phenomenon in question?)
Then we must find any evidence for, (or against), the evolution of the natural phenomenon in question.
___________________________________

‡
Behe claimed that evolution of the eye was impossible because it is irreducibly complex. The claim was that if you took away part of the eye, it became useless, and as such could not be an evolutionary intermediary. Dawkins, (and others) showed how, by a series of intermediaries, from great simplicity in evolutionary origin, to the extant complexity of eye structures, there is a feasible set of evolutionary steps. The key to the argument in that case was to work forwards from origins, not backwards from what is extant, claiming in the latter attempt, that it was impossible.

Then some creationists responded by saying that: 'that does not show that it actually happened'. But to my mind, the attempt by Dawkins et al, was not to show what actually happened, but to show that it was possible for eyes to have evolved, and so the claim of irreducible complexity was false. What Dawkins was doing, was saying that the eye is evolutionarily possible, (in order to put the claim by Behe et al, out of the picture).

Of course now the job was to do the research to show the evidence for actual eye evolution. As a non-expert, I'd guess that a major part of that would be genetics, and looking at the evidence in the DNA of multiple species.

Habitat selection is more important than neutral drift in that it is ...selective. Many plants use animal vectors to spread their pollen & seed, and these animals make rational choices about where the best mates and food is. it is still NS, of course, but NS with cognition.

Andrew4Handel wrote:
But in general I do not think invoking an alleged conceptual principle of evolution amounts to a testable explanation. I am not sure what is supposed to follow if evolution is true. If something does follow it should be detectable. So for instance if gays are the result of fertile mothers this should be the case. Gays with few siblings are counter examples.

This is begging the question that there can be only one factor that results in gay offspring.
Also, just to keep in mind, evolution is about the survival/reproduction of the species, not the individual.

Andrew4Handel wrote:
But in general I do not think invoking an alleged conceptual principle of evolution amounts to a testable explanation. I am not sure what is supposed to follow if evolution is true. If something does follow it should be detectable. So for instance if gays are the result of fertile mothers this should be the case. Gays with few siblings are counter examples.

I imagine very few gays (or anyone else for that matter) are the result of infertile mothers.

Fenrir wrote:

Andrew4Handel wrote:
But in general I do not think invoking an alleged conceptual principle of evolution amounts to a testable explanation. I am not sure what is supposed to follow if evolution is true. If something does follow it should be detectable. So for instance if gays are the result of fertile mothers this should be the case. Gays with few siblings are counter examples.

I imagine very few gays (or anyone else for that matter) are the result of infertile mothers.

Although, interestingly enough, while Andrew may have thought he was making a merely hypothetical example, guess what. There actually exists evidence that is along the lines he is suggesting:

A correlation between fraternal birth order and male sexual orientation has been suggested by research. Ray Blanchard identified the association and referred to it as the fraternal birth order effect. In several studies, the observation is that the more older brothers a man has from the same mother, the greater the probability is that he will have a homosexual orientation.[1] It has sometimes been called the older brother effect. It has been estimated that 15% of the homosexual demographic is associated with fraternal birth order.[2]

Though in return, I'll offer this little lot in order to destroy once and for all the sad creationist assertions about "design" being responsible for the biosphere ... because frankly, only a truly warped entity would "design" this lot

The single, most commonly misunderstood notion that I see repeated in this thread as well from the Creationist-type side, is that there is some sort of INTENTION involved with the Theory of Evolution. It's ultimately where this OP goes off the rails, just as so many on that side do.

I remember being mis-educated as a child myself, about evolution, by well meaning teachers who erroneously used phrases such as that this or that feature or characteristic of an entity evolved to be as it is because it was necessary or better for the entity in question. This error was typically compounded by telling us that scientists could reason backwards from what is, and deduce that whatever we see here and now, must have, at some point in the past, been necessary in order for the entity in question to have survived.

Anyway, that's the historic reason which I directly witnessed, as to why so many people don't understand the most important fundamentals of evolution.

Another important element, which only people in the actual field of the DISCIPLINE of the study of Human History are at all aware of (and not even a majority of them), is the influence of the idea that as existence has moved through time, that there has been overall PROGRESS. This notion appeals to the many egotists of the world, who want to think that we today are smarter than all who came before, or who want to justify all manner of abuses of others in the present AND in the past.

This relatively modern idea poisons all manner of modern day understandings of reality, and at least indirectly contributes to things such as this OP's erroneous understanding of evolution.

Basically, the idea that all change which occurs over time is POSITIVE, necessarily implies INTENTION. And if there is such a thing as INTENTION driving change, then there must be something which INTENDS. Thereby, many Creationists think that non-creationists are secretly "theists who worship science."

So. No. There is no INTENTION involved with the theory of evolution.

Very true. A4H's question is the equivalent of asking: If the shape of a coastline was created by erosion and other geological forces, then what is the purpose of the particular shape it ended up having?

igorfrankensteen wrote:The single, most commonly misunderstood notion that I see repeated in this thread as well from the Creationist-type side, is that there is some sort of INTENTION involved with the Theory of Evolution. It's ultimately where this OP goes off the rails, just as so many on that side do.

I remember being mis-educated as a child myself, about evolution, by well meaning teachers who erroneously used phrases such as that this or that feature or characteristic of an entity evolved to be as it is because it was necessary or better for the entity in question. This error was typically compounded by telling us that scientists could reason backwards from what is, and deduce that whatever we see here and now, must have, at some point in the past, been necessary in order for the entity in question to have survived.

Anyway, that's the historic reason which I directly witnessed, as to why so many people don't understand the most important fundamentals of evolution.

Another important element, which only people in the actual field of the DISCIPLINE of the study of Human History are at all aware of (and not even a majority of them), is the influence of the idea that as existence has moved through time, that there has been overall PROGRESS. This notion appeals to the many egotists of the world, who want to think that we today are smarter than all who came before, or who want to justify all manner of abuses of others in the present AND in the past.

This relatively modern idea poisons all manner of modern day understandings of reality, and at least indirectly contributes to things such as this OP's erroneous understanding of evolution.

Basically, the idea that all change which occurs over time is POSITIVE, necessarily implies INTENTION. And if there is such a thing as INTENTION driving change, then there must be something which INTENDS. Thereby, many Creationists think that non-creationists are secretly "theists who worship science."

So. No. There is no INTENTION involved with the theory of evolution.

There is though. But not in the creationist sense of an "overmind". Brains and senses allow organisms to evaluate their environment so that they can make choices about survival and reproduction. They mistake this intent by animals as the intent of an overmind. So there has been progress with cognition and perception, but of course, it not necessary to have a brain to survive, unless you are competing with others in your species with good eyes or brains or whatever.
..and plants evolve to exploit animal cognition and sensation to spread their pollen seed, because such dispersal by animal is deliberate rather than by chance as in wind or water dispersal. Birds, bees etc go where the pollen is. or fruit or whatever.

Second, like is generally highly cooperative, and that, when you think about it, is the result of competition. Surviving alone is usually very difficult, except in nutrient sparse environments. Complexity may be the result of drift, but complexity involves the possibility of sophistication: complex brains and senses. Even bacteria use quorum sensing. So even for [relatively] simple life forms, cooperation is common, if not cognitive.

And all this from imperfect replication that "explores" "design space". What the creationist can't accept is that evolutionary forces, not some over-mind, can kick-start and maintain these complex systems.

Thomas Eshuis wrote:
Also, just to keep in mind, evolution is about the survival/reproduction of the species, not the individual.

No. Evolution is about the distribution of Genes in the Gene Pool.

Evolution is a side effect.

igorfrankensteen wrote:Evolution is a side effect.

Of what?

Shrunk wrote:

igorfrankensteen wrote:Evolution is a side effect.

Of what?

Evolving.

NineBerry wrote:

Thomas Eshuis wrote:
Also, just to keep in mind, evolution is about the survival/reproduction of the species, not the individual.

No. Evolution is about the distribution of Genes in the Gene Pool.

OOh, It's like Dawkins vs. Gould all over again!

Backing up a bit, the issue of homosexuality as a conundrum for evolutionary theory often comes up, and I'm not sure why. There's a misconception that every single trait an organism possesses must be adaptive, which is even more misconceived when applied to traits that are present in only a minority of a population.

The question also assumes that the genes that lead to the homosexual trait only produce that one phenotype. You could just as easily ask "What is the evolutionary advantage of rheumatoid arthritis?" which would be a difficult question to answer, until you understand that rheumatoid arthritis is a result of a malfunction of the immune system. The question then becomes "What is the evolutionary advantage of the immune system?", which is easily answered.

I also just noticed that this thread on the scientific topic of evolution was started in the philosophy section. That's probably the problem right there.

Shrunk wrote:

igorfrankensteen wrote:Evolution is a side effect.

Of what?

Natural selection, that's why it's referred to as evolution by natural selection.