quote:Originally posted by Strider: King of Men, are you familiar with game theory?
Well, I know what it is, I can recognise a Prisoner's Dilemma when I see one, and I've read a couple of books on it. (Including Selfish Gene, to be sure.) But it's all layman's knowledge, really.
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Here's a question, though, about recent human evolution, conjured in my mind from the mention of the "mutant" human becoming a weight lifter.
Basketball and football players tend to be stronger, taller and more athletic than the average human. As size, strength, speed and agility became valued by our society, we created a niche of professional sports for people so abled to fill. So, that said, are we somehow contributing to evolution of our species in this way?
Another thought is the use of corrective eyewear, and I guess "de-evolution" - if that's even a word. Our intelligence allowed us to create a tool to correct poor vision, which then in turn allowed those with poor vision to be useful members of society, which then in turn allowed them more reproductive opportunities. Have we used our intelligence in tool making to decrease the overall eyesight of our species? Surely there couldn't have been as high a percentage of humans with poor vision a thousand years ago or more.
Also, is animal husbandry a form of guided evolution? Breeding dogs for certain traits, or breeding horses for certain traits... only allowing animals with favorable traits to reproduce. It's not natural, and it's forcing the issue, but isn't that right in line with how evolution happens?
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KoM: of course there is a reason, it improves survival frequency, just like any other gene. There's nothing out there that causes for genes giving individual advantage to appear more preferentially, either, its just that they're selected for when they do, simply by animals possessing them suriving more often than those that don't, on the whole. This happens regardless of whether the gene just improves individual survival chances or if it improves survival chances of the local ecology as a whole. You seem to somewhat misunderstand how evolution occurs.
As a side note, genes are not necessarily selected for by all the individuals possessing them surviving better; sometimes genes only cause a subset of the individuals possessing them to survive better, by inducing other carriers of the gene to be, say, particulalry protective, perhaps resulting in a higher death rate among those individuals.
Furthermore, while 'parasitic cheater genes' do exist, they're not terribly successful. Since you know the basics of the prisoners' dilemma, the following should be interesting to you:
The equilibrium for a once off prisoners' dilemma is defect. The equilibrium for an infinitely repeated prisoners' dilemma is cooperate. The best overall strategy we know of (and quite likely the best simple general strategy possible) for any long-running prisoners' dilemma is tit for tat: that is, cooperate by default, but punish defection with a defection immediately following.
Put in natural selection terms, genes that 'try' to 'cheat' get smacked down by tit for tat strategies (which we see all over the place, coincidentally, its a very successful strategy for all sorts of organisms).
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quote: Basketball and football players tend to be stronger, taller and more athletic than the average human. As size, strength, speed and agility became valued by our society, we created a niche of professional sports for people so abled to fill. So, that said, are we somehow contributing to evolution of our species in this way?
If a professional athlete is more likely to have a large number of viable offspring, then this would be a form of genetic drift. I'm not sure you could call it evolution, however, unless the tall professional athletes preferred breeding with other professional athletes enough that they became so large (or different enough in some way) that they either couldn't reproduce with a normal human, or they all choose not to.
That is if we are talking about the speciation aspect of evolution.
quote:Another thought is the use of corrective eyewear, and I guess "de-evolution" - if that's even a word. Our intelligence allowed us to create a tool to correct poor vision, which then in turn allowed those with poor vision to function more capably in society, which then in turn allowed them to be useful members of society, which then in turn allowed them more reproductive opportunities. Have we used our intelligence in tool making to decrease the overall eyesight of our species? Surely there couldn't not have been as high a percentage of humans with poor vision a thousand years ago or more.
I've made similar observations before, but be careful, or else you will be accused of supporting eugenics.
I myself am quite troubled by the way humans as a species have removed a ton of natural selection mechanism. Not just in eye-sight, but in genetic disorders like asthma and diabetes. Half the people I know have poor enough eye-sight that they wouldn't be able to survive without corrective lenses. My girlfriend Niki is one of them, and my children may very well be as well. My mother had a mishapen uterus, which would have prevented her from having children herself. Meaning she would have been selected against without modern medicine. So I very well may be carrying genes for mishapen uteruses, which would have been selected against in any other era. It is troubling.
The traits are not desirable, but very few people sexually select against these traits, and natural selection is being circumvented. Nobody says "Wow, I'd love to date that girl, but she wears contacts and so has inferior eye-sight genes." It doesn't mean much in a relationship, and when your kids end up having it, you just deal with it.
What can we do about it then? Not much. I don't think there's many people left in the first world who aren't carrying some genes which would have been selected against at some point in their ancestry if not for modern medicine.
Genetic engineering could someday remove these traits, but again, good luck advocating this without being compared to Hitler or being called a monster in some way. Our species may just have to deal with it.
quote:Also, is animal husbandry a form of guided evolution? Breeding dogs for certain traits, or breeding horses for certain traits... only allowing animals with favorable traits to reproduce. It's not natural, and it's forcing the issue, but isn't that right in line with how evolution happens?
I absolutely use domesticated animals as examples when describing evolution. We've basically created several species of animals ourselves in the last ten to twenty thousand years. That's a microsecond in evolutionary terms. It happened so fast because we practiced an extreme form of artificial selection.
I use the Greate Dane and Chihuahua types of dogs as examples of speciation. Sure, they are both canis domesticus. However, this is only because there are slightly larger dogs that a Chihuahua can mate with, and then that breed can mate with a bigger breed and so on right up to a Great Dane.
Take those two breeds and put them on an island together (assuming both breeds could survive there) and now you have two separate species, because there's no way the two populations could mate with eachother. Bang, you went from one species to two. You've had a speciation event. Leave the two population on the island for a few (hundred) thousand years, and their genes will have sufficiently diverged that they will never be able to mate, even through intermediaries.
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Actually Xavier, I'm pretty sure I'm a superiorly healthy individual with perfect genes. And will take it upon myself to sire as many children as possible to propagate my genes around the globe. I shall begin tomorrow!
quote:Well, I know what it is, I can recognise a Prisoner's Dilemma when I see one, and I've read a couple of books on it. (Including Selfish Gene, to be sure.) But it's all layman's knowledge, really.
Well then we should be agreeing!
This is the section in the selfish gene where he talks about ESS's(evolutionarily stable situations), or something like that. The help the community gene WOULD be selected for, precisely because in the long run it would help propagate the gene at the individual level, because all individuals would benefit from cooperation.
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I don't see the eyewear issue as bordering too closely on eugenics... though if you take the same phenomenon and apply it to the rapid growth of learning disabilities, it hedges closer to that line.
Starting about thirty to forty years ago, we started to make more of a push to help students with learning disabilities succeed. More and more effort, time, money, and resources were invested in getting students who would have failed out of school (or worse) sixty years ago.
In the last ten years, the number of students enrolled in special education programs in this country increased by 40%. I think there is a correlation, much like the eyewear example. We have used our intellect to compensate for a problem, in turn causing that problem to be genetically passed on more easily.
Though I'm not advocating abandoning students with learning disabilities, it seems, if we follow the eyewear plan, that such difficulties may become as prevalent as glasses.
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There's no reason an evolutionarily stable strategy can't lead to disaster for the species, as indeed Dawkins points out. It just has to lead to success for the individual. Humans have exploited this in a couple of cases to wipe out insects over local regions : You make a strain of insect that is extraordinarily fertile, but only has male children. Of course, because it's so fertile, the strain is strongly selected for, so now you have lots and lots of fertile insects, but rather fewer females. But that doesn't matter : The selection pressure has not changed. The fertile ones are still selected for, they have more children than the vanilla version. And that's going to be true right up to the generation in which there's only one female left; at this point, random factors begin operating. But even so, because most of the males in any given generation will carry the fertility gene, chances are good that the one remaining female mates with one of them, wiping out the species. (And even if she doesn't, her daughters probably will.) It's evolutionarily stable to have the lots-of-male-offspring gene; it's also a total disaster.
About community-level selection, well, we're none of us biologists. I believe this is a point of some contention within the field. It does seem that we may be speaking of slightly different things, though. You are talking about the evolution of cooperation, which plainly does happen, though not always. I am talking about the evolution of stability, which I think does not happen.
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quote:Originally posted by FlyingCow: In the last ten years, the number of students enrolled in special education programs in this country increased by 40%. I think there is a correlation, much like the eyewear example. We have used our intellect to compensate for a problem, in turn causing that problem to be genetically passed on more easily.
You are assuming a correlation between graduating high school and having many children, which is totally non-obvious.
As for eyeglasses, just how good do a farmer's eyes need to be, anyway? It's only in a literate society that this is a problem. Also, it is not clear that myopia is a completely genetic trait.
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Thinking more on what you said about speciation, I didn't think that "inability to mate with one another" was a prerequisite for having two different species.
Granted, animals of vastly different species can't procreate - otherwise we'd have pot bellied elephants overrunning the country.
But, unless I'm wrong, wolves, coyotes and domestic dogs are all separate species - yet I've seen dogs that are cross husky/wolf mixes, and others that are coyote/shepherd mixes. Also, horses and donkeys are different species, though they can mate and produce mules (though almost always sterile, they would be considered offspring nonetheless)
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quote:But, unless I'm wrong, wolves, coyotes and domestic dogs are all separate species - yet I've seen dogs that are cross husky/wolf mixes, and others that are coyote/shepherd mixes. Also, horses and donkeys are different species, though they can mate and produce mules (though almost always sterile, they would be considered offspring nonetheless)
The definition isn't perfect (are any?), but the versions I've seen include the possibility that two species could reproduce, but simply don't (in nature).
So coyote's and wolves are two different species, not because the can't mate, but because they don't mate (generally).
This, of course, is just my understanding. I could quite easily be wrong .
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quote:You are assuming a correlation between graduating high school and having many children, which is totally non-obvious.
Not really, as high school graduation has nothing to do with it. I don't see a high school degree as anything of intrinsic value to a person. However, identification of problems early enough allows teachers to impart strategies to ovecome disabilities (be they learning disabilities or social ones) that students to function within a close approximation of average. Unidentified and left to their own devices, these students would have fallen though societies cracks.
Not to be too morbid, but certain learning disabilities led, in the past, to a high rate of teenage suicide - though early identification can help these individuals through that rough time and into adulthood. Also, students with social disabilities (asperger's, nonverbal learning disability, etc) are educated in interpersonal interaction and social skills, giving them a better chance in life of finding a partner.
There has been a marked rise in learning disabilities in the last decade or so. Twenty five to thirty years ago, there was a real push for special education. Many of the parents of students with learning problems have learning problems themselves. I see a correlation, though I admit there may be none.
If the next ten years show another huge rise, as the last ten years or more have shown great strides in special education theories, that might point more strongly towards correlation.
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quote:Also, horses and donkeys are different species, though they can mate and produce mules (though almost always sterile, they would be considered offspring nonetheless)
The definitions of "species" that are based on mating always have the qualification that the offspring must be "viable". The example used in biology classes (at least mine) of why this qualification is added is exactly the one you used here (horses and donkeys making mules). The word viable in this context means that the offspring is capable of producing offspring themselves.
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quote:Originally posted by FlyingCow: We have used our intellect to compensate for a problem, in turn causing that problem to be genetically passed on more easily.
Though I'm not advocating abandoning students with learning disabilities, it seems, if we follow the eyewear plan, that such difficulties may become as prevalent as glasses.
Only if you assume that people with higher levels of education have more children than people with lower levels of education. In general, I believe that the opposite is actually the case.
Of course, you're also making the assumption that learning disabilities are genetically inherited traits. They may be, but I haven't seen any studies that show that they are. Is anyone aware of any? Honest question--this is something I don't know enough about to speculate, but I'd love to know more.
In general it's hard to say what problems are genetic and which ones have environmental causes. Take asthma, for example. It's natural to assume that it's an inheritable trait, but is it actually? The rapidly rising incidence of asthma in the 1st world suggests that the problem is environmental rather than genetic, and in fact it has recently been discovered that certain intestinal "parasites" common in the third world but more or less eliminated in the first provide their hosts with freedom from asthma (which is why I put "parasite" in quotes. In light of this it seems to me that these worms are actually symbiotes).
[Edit--man, this thread is moving too fast for me. I got a bit busy with something work related, and by the time I was able to get back and finish my post some of the stuff I was saying had already been addressed.]
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There are some mules that are viable, though they are very rare, at least according to what I found on teh interweb.
But since dogs can have "wolf blood" or "coyote blood" in them, isn't that an example of interspecies mating? They are different species (canis lupus, canis latrans, canis domesticus), but close enough cousins to have offspring?
Is it maybe you can't mate outside your genus?
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quote:But since dogs can have "wolf blood" or "coyote blood" in them, isn't that an example of interspecies mating?
I don't know if you missed my post above my last one. It appears to adress this point:
quote:The definition isn't perfect (are any?), but the versions I've seen include the possibility that two species could reproduce, but simply don't (in nature).
So coyote's and wolves are two different species, not because the can't mate, but because they don't mate (generally).
This, of course, is just my understanding. I could quite easily be wrong [Smile] .
I don't know if coyotes and wolves ever mate in the wild, but my guess would be that they don't. Either because of geography, behavior, or sexual selection. They could mate, but they don't. I think those dogs you've heard of come about because someone bred a dog with a captured wolf or coyote, not a wild one.
If a dog happens to go stray, and somehow manages to get a wolf to reproduce with it, I don't think that's going to affect the definition any. I would think it allows for very very rare exceptions. If 99.999% of the time a wolf is going to mate with a wolf, and a coyote with a coyote, the species demarcation is still safe.
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By the way, X, your point about elephants having a single trunk to work with, as opposed to a pair of them, is a very good one. A species with only one dexterous appendage would have a much harder time developing sophisticated tools and so forth. If the trunk branched into two distinct sub-trunks that would be a different story, but I'm not aware of that's ever having happened outside of SF writers' imaginations.
So what animals have opposable digits, or reasonable facsimiles thereof? All of the higher primates have them (and all of them but us have opposable toes as well, I think). What about lower primates? I'm pretty sure that New World lower primates do, but that their Old World counterparts don't. Pandas have opposable bone spur thingies that may as well be thumbs. Opossums have opposable toes on their hind feet, I believe. Don't some varieties of sloth have them as well? What about koalas?
::off to do some checking::
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quote:So what animals have opposable digits, or reasonable facsimiles thereof? All of the higher primates have them (and all of them but us have opposable toes as well, I think). What about lower primates? I'm pretty sure that New World lower primates do, but that their Old World counterparts don't. Pandas have opposable bone spur thingies that may as well be thumbs. Opossums have opposable toes on their hind feet, I believe. Don't some varieties of sloth have them as well? What about koalas?
I know there are a lot of animals which have opposable thumbs the same as we do.
I'd say that if you wiped out all of humanity, that intelligence on a human level would have a good chance of developing again.
It may take millions of years, however, and there's no guaranty it would happen even then. We don't really know how rare the circumstances are for the mutations which led to us to both occur and be selected for. Perhaps it would take a catastrophy.
I'm not sure which mechanism of evolution, be it gradualism, punctuated equilibrium, or a combination of the two, is in vogue these days .
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Huh--koalas actually have two thumblike digits on each front paw. I wonder what advantage having two of them on each had confers? Maybe they get their fingers lopped off a lot? I'm not finding any good articles that discuss it, or photos that are specifically intended to display the two thumbs, but from what I'm seeing it looks like they're both on the same side of the hand. I'd assumed when I first read about it that they were on opposite sides of the hands. Here is the best picture I've seen so far. I'd really like to see one taken of the koala's palm.
::continues to search::
Ooh, here is a page that has some good photos of the palm of a koala's hand, as well as a diagram of it. Cool!
It seems like opposable thumbs and toes occur in arborial or at least partially arborial species. Anybody think of an entirely non-arborial species other than our own that has them?
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Sorry, X, missed that one post. I understand what you're saying now.
In response to Noemon,
quote:Only if you assume that people with higher levels of education have more children than people with lower levels of education. In general, I believe that the opposite is actually the case.
I don't assume that at all. In fact, people with more severe learning disabilities have a harder time achieving higher levels of education.
My point was twofold.
Previously, as in several decades to several hundred years ago, people with severe learning disabilities or social disabilities were often shunted to the side of society. They had trouble acquiring the life skills needed to find and keep a partner, and to raise children. Many with more severe social problems committed suicide because they couldn't fit in, or became reclusive. Another portion of these became homeless, without a support network to give them the life skills needed to survive and thrive in society.
Now, we have found ways of identifying learning and social problems early on. We know far more about the brain and its effect on learning and behavior, and we can give young students ways of compensating for their difficulties. Caught early enough, students with more severe problems can be trained to live functioning lives with modification and accommodation of their daily schedules and learning programs. They are more likely to be able to find and keep a job, find and keep a partner, and have and raise children.
Level of education is a happy byproduct of increased ability to function in social and academic environments. Greater ability to have healthy interpersonal relationships (and, thus, a greater likelihood of children) is also a happy byproduct of the strategies learned to adapt.
Are these disorders genetically passed on? I have no empirical proof that they are. I have much anecdotal evidence to believe that they are, however. For instance, there is a family (clan?) in the town I taught that had at least two or three children in every grade level. Nearly all of them were identified as needing special education. Many times students who have body control problems (difficulty sitting still, constant tapping or making noise, etc) have parents that come in with facial tics or similar body control problems.
I'd be very interested in a more empirical study of this, to be sure. Right now it's just a pet theory.
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I started on my post before you'd posted the bit about suicide, but that (and probably to a greater degree the ostracism that you talk about) would definitely be limiting factors for reproduction (except through rape, of course)--good point.
I would love to see some studies done on the heritability of the sorts to learning disabilities you're talking about, as well as more benign ones like dyslexia (not that dyslexia is a walk in the park, but I'd rather have that than something that would cause me to be shunned by my peers).
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A lot of that is due more to an increase of detection than an increase of occurance.
My father, one of the smartest people I know, reads at a fairly low reading level. He failed a grade, and was told on more than one occasion to put his head down and stop asking question because they were going to just pass him along.
He had some learning disabilities, but they didn't considering him learning disabled because the term didn't exist back then. They weren't severe enough to prevent him from becoming successful, but they made things for him really hard at times.
They just called him the class clown.
If he had been in school when I was in school he probably would have been in a special reading program like my nephew is, given more time and more instruction to get past his reading problems.
Who knows what he might have accomplished then...
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I think that what your dad experienced is a more benign sort of disability than what FlyingCow is talking about. Again, not that benign is really the right word, as it minimizes something that doesn't deserve minimization.
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quote:The traits are not desirable, but very few people sexually select against these traits, and natural selection is being circumvented. Nobody says "Wow, I'd love to date that girl, but she wears contacts and so has inferior eye-sight genes."
Well, no. But it is very possible that the girl is wearing contacts because she feels that she will be more attractive by hiding her poor eye-sight genes rather than broadcasting them by wearing glasses.
erm, which just supports your thesis that we are using intellect and technology to circumvent natural selection.
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