Humans are losing.

Example: A subpopulation of green wibble-wobbles mutate an allele that provides fur. Is that an increase or a decrease in fitness?It depends on whether or not they live in the Arctic circle or the Sahara desert. In fact, it may even depend on factors we know nothing about (like, whether or not wibble-wobbles like the cold). If the fur allele increases in frequency over time, we know that the allele represents an increase in fitness. If it decreases, we know it represents a decrease in fitness. Let's say that it increases.Therefore, we know that having the allele means greater fitness. But let's say that you have a crystal ball, and you know that in 200 years global warming will change their environment from chilly Arctic temperatures to balmy tropical ones. At that time, fur will be a liability and (again, from your crystal ball) we know that the allele will begin to decrease in frequency, and therefore that having it represents a decrease in fitness.So, does the allele mean more or less fitness? The answer is: both-1) Greater fitness now;
2) Lesser fitness sometime in the future.Do you understand that I'm talking about now, and you're trying to rebut that with what might happen in the future?Do you understand that the fitness of an allele in the future, when conditions are different, is not relevant to looking at the fitness of that allele now, under present conditions?I don't know how to make it any simpler than that. Am I still not making any sense to you?This message has been edited by crashfrog, 05-03-2006 11:49 PM

Let me clarify. In post 20 you said: In post 22 your only reference to selection is: Which is a completely nebulous statement that doesn’t identify any selective force.
Differences between populations and their growth rates can arise for many reasons other than selection - your heavily-touted difference in birth rates for example. We don't 'detect selection' by comparing populations, but by identifying causative influences that affect survival or reproductive success of individuals differentially. Like industrial melanism in Biston betularia. Like disease and parasitism. These are selective forces. What selective force are you postulating?So while I accept that we currently have lower birth rates in the west than in the developing world, I really would like you to clarify how you think that "our environment is selecting against our alleles". Their replication might be slower, but that doesn't amount to any form of selection against them. Your refering me back to post 22 just seems like an attempt to obfuscate and avoid this question.In regard to selection you also said: I accept that we don’t see an impact of such selection on population growth rates yet, but that doesn’t allow us to conclude that no such selection is occurring - only that the net effects of such selection are not yet sufficient to counter the birth rate. 'Yet' being the pivotal word. I agree with you here, but I think you will agree there are many independent lines of evidence to suggest that many of these populations will have to crash eventually. What happens to the alleles they contain at that point is uncertain and will depend on emigration, survivorship, etc. but I predict some severe bottlenecks. You seem to view the human species as one large homogenate, whereas I see it more as a series of ecologically separate populations that have potentially very different fates, regardless of a little gene fow between them, hence my comments on effective population size. No, we are not separate species, but we are functionally separate societies in relatively separate ecosystems and hence our gene pools, even with some gene flow, are subject to locally specific differences in selective forces. I have spoken about some of these selective forces I think will affect these populations differentially. I am still waiting for you to identify the selective force you think is “selecting against our alleles.” Not at all. It was a different issue, one of medical intervention increasing the ”genetic load’ of our population. As I have pointed out, there is every reason to believe that all kinds of negative selective forces are starting to affect survival in Africa, but until they start reducing more of the survival prior to reproductive age, you are not going to see much effect on population growth. I’m sorry you feel that way. At least I have managed to refrain from insulting you. Oh. You mean like your clumsy attempt to evade your blunder about the ”environment selecting against our alleles? Please. Post 22 contains no such information. Stop trying to obfuscate. Fine. That is true if you consider the human race as one large homogeneous population. Theoretically, it can be viewed that way, but in practical terms whole populations often either survive or die as ethnic groups or societies. Look at all the examples of genocide. All I’m saying is there are lots of types of selective forces that can affect the survival of entire geographic populations differentially. Like war for example. I guess I don’t accept your inference that somehow we in the west will inevitably lose genetic representation in the human race just because there are poor countries breeding faster than we are. Yes, they technically have higher Darwinian fitness measured by current rates of reproduction. Will that be the case for much longer is the question. I doubt it.

I find this an extremely interesting conceptualization. An ecological approach appeals to me on a number of different levels. I just never considered it in relation to H. sapiens. It may be off-topic for this thread, unfortunately. Would you be willing to open a new thread to expand on this? It could be endlessly fascinating.

Let he who is without fear of recompense cast the first stone...AbE: You realize, of course, that this could open a rather ugly can of worms ? I will particpate, of course, but I am not sure I want the responsibility of initiating...This message has been edited by EZscience, 05-04-2006 09:21 PM

Ya mean we have to be unemployed? I guess you're probably correct. I can see the discussion being characterized right out of the starting gate as being somehow "racist" and then deteriorating from there. Let me think about whether my intellectual curiosity (and courage...) is up to the task.

It would help. I find myself borrowing a lot of time from my writing and editing responsibilities to participate here, but it is fun and intellectually stimulating.Perhaps a good discussion could be had by raising the question of just how relevant or meaningful the strict Darwinian definition of ”fitness’ is for the further evolution of humans at this point. This came to me in the course of this discussion with Crash where he seemed so concerned about the rate at which non-western, UD countries were gaining genetic representation in the human race, as he sees it ”at the expense of our alleles’. Numerically, I guess that’s true, but my gut reaction is, so what? How many truly unique alleles do each of us carry, if any? All my alleles are all likely present in multiple copies in many other individuals. The only thing ”unique’ about me is my genotype - and genotypes are completely destroyed by recombination every generation. However, what a unique human genotype is able to create can live on . Can't individual humans influence their species' evolution in permanent and lasting ways without making a genetic contribution?I am thinking of science, culture, and intellectual creation/invention. Who cares about how many stinkin’ genes you are leaving behind if you can bequeath a hefty publication record to the enterprise of science that forms the basis of future discoveries and advances for the human race? (My true life’s goal, laid bare ).The significance of DNA to nature is two-fold. First, it holds the information needed for the construction of all lifeforms during their development and, in this regard, will never have a substitute. But it is also the only means of preserving any kind of information across generations for most animals. In this context, humans have many alternatives not available to other animals - language and a record of history and science.So the next question becomes, which will be more important to our human destiny as a species - our genetic information or our cultural information ? I would argue the latter.The strongest forms of selection currently acting on humans are almost all either directly or indirectly the result of other human activities (wars, mismanagement of the environment, overpopulation etc.). We (human societies) are now the primary cause of most selection acting on our own species and are, thus, largely responsible, consiously or unconsciously, for our own evolution. The fate of humanity (extinction vs. continued existence) rests on our ability to evolve a culture of sustainable existence on this planet - NOT on mutation + NS resulting in dramatic changes to our genetic makeup.I suppose this could be transposed to form the OP of a new thread (Does Darwinian fitness even matter for human evolution?) if admins feel I am ranging too far afield in this one.Here I go again spending a half hour on a post when I just got a MS back from review. Where are my priorities ...?

Schraf has a point here, Crash.A study was recently done on what women find attractive...
and it was found that women who are less financially independent are more likely to choose a man with wealth, over his looks.Those who were financially independent, however, went for looks.
Why women are changing their minds about menWhatever happened to personality and a sense of humor? Of course, maybe these things should never be generalised...

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"The good Christian should beware the mathematician and all those who make empty prophecies. The danger already exists that the mathematicians have made a covenant with the devil to darken the spirit and to confine man in the bonds of hell." - St. Augustine

So, you completely missed this exchange? Are you done being ridiculous, now? Non-random differential reproduction is selection, by definition. I've already put forth the causal mechanism (in two posts, now.) Humans in the West are being selected against, detectable by the fact that our genes represent a decreasing frequency within the human gene pool. Sure. Granted.So what? The fitness of these genes in a future environment is irrelevant to their fitness in this environment. That doesn't seem to be born out by the data (and again we see how you prefer to substitute your own speculations for actual evidence.) The evidence indicates that genetic differences between these populations are decreasing, not increasing, and that's understood to be a function of how transportation technologies mean that these populations are becoming decreasingly geographically seperated. Could you stop being evasive and actually answer my questions as I ask them? Quote mining me isn't going to get you very far. Here's what I asked you:

quote:

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If we're talking about me, personally, there's little if any chance of my genes recombining with anybody but my wife's, anbd likewise for her. Are you telling me that we don't belong to any reproductive population at all? That we're, essentially, our own species?

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And here's what you quoted:

quote:

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Are you telling me that we don't belong to any reproductive population at all? That we're, essentially, our own species?

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And then here's what you answered: Did you think I wouldn't notice? Go back and answer the question that I asked. Different issue? That's the topic of this thread.What do you think we're talking about, exactly? I'm asking because if you're laboring under a drastically different idea of what the topic is, here, that might explain why your posts have so consistently seemed to be evading my arguments. Survival past reproduction is not relevant to fitness, so your attempt to make an argument from unknown factors is kind of pointless. Unless reproductive success is being affected, the force is not selective. A disease that kills only the extremely elderly, for instance, is not a selective force. Are you kidding me? Your constant attempts to misrepresent me, and your quote mining in this message, are an insult to my intelligence. Why is it that you refuse to approach this discussion honestly? I was being perfectly polite until you started acting like an ass. Like here, where you misrepresent me again: Inevitably? That was never my position. It's merely my position that that is what is happening now, and you've presented nothing to rebut that. That's been my sole position all along. Are we done, now?

Its hard for me to view voluntary reproductive restraint as a form of 'selection', but I agree that birth control is a choice more available in the west. But it's a choice individuals can make to voluntarily reduce their fitness - so is abstinance and suicide. So now I am pondering whether we would have to accept abstinance and suicide as forms of 'selection' if we accept birth control availability.A more interesting question might be to ask why this is occurring, apparently in direct contradiction to the expectations of NS. Such non-adaptive behavior should be selected against. You are inferring the action of selection without demonstrating it.
I refuse to accept that a simple difference in rate of reproduction equates to any form of selection. Recall Darwin's original inference that animals produced more offspring than could survive. Selection is the process whereby certain ones die and others don't. Higher rates of reproduction are normally advanatageous under selection, but reproductive rate alone does not constitute any form of selection. It just provides the raw materials. There are situations where both reduced fecundity and delayed onset of reproduction can evolve as a consequence of selection acting on other traits and actually be favored under selection. If not, we wouldn’t see such trends evolve in so many taxa of large animals. Most evolved from smaller ancestors with higher reproductive rates.Under your reasoning, reduced fecundity and/or delayed reproduction cannot evolve because, by your definition of selection, such traits can only be evidence of a selective disadvantage. You are using the term in its broadest sense without identifying any 'selective force'. For example, if I isolate two aphid clones from field collections and clone A has twice the rate of reproductive rate of clone B, under your broad definition clone A will be selected for and clone B, against. I would say there is no selection acting - we have just compared reproductive rates and found them to be different. I don't see any need to use the term 'selection' unless there is some detectable, external force that is limiting to survival or reproduction. I am still finding it difficult to accept your view of voluntary reproductive restraint as such a force, but I don’t want to belabor the point any further. Definitely. But I think that as humans we have a pretty good picture of some of these future environments that evolution doesn't have. Given that, it doesn't seem unreasonable to project certain changes in the mean fitness of particular populations based on their geographic locations. This is true, but we are far from being one large homogenate yet. I was merely emphasizing ecological, political and with the potential to affect the survival of large populations and the specific genetic structure they contain. I think you mean less genetically separated. The geography doesn’t change. But yes, this is true. I never intended to mis-represent you. These were impressions I got from your argument. I don’t dispute that they are currently achieving higher Darwinian fitness, so I don’t need to rebut that. I am just not accepting that there is any selection acting specifically against us. A higher reproductive rate is not invariably adaptive. I'm ready to move on if you are.
I'd like to hear what you have to say about post 36.

Sure. Abstinence doesn't work, though, so we can throw that right out. People who claim to be "abstinent" don't have any less sex than anybody else.Suicide? The largest cause of suicide is, of course, depression; and we know that depression is related to chemical states in the brain. It's not outside of the realm of possibility to suggest that a gene exists which, previously, had represented negative fitness for its carriers (by making them kill themselves) and been selected against, but now in the presence of SSRI drugs, no longer represents negative fitness. The changing gene frequencies demonstrates it, and I've provided the mechanism. As you've stated that's what you need to prove selection. How many times do I have to rebut this, EZ? Go back to the reality. What is the reality of the situation? What effect on our population is reduced fecundity and delayed reproduction having in reality? The population statistics are out there on the internet. Look them up and see for yourself. Posts 22 and 38. The selective force has been specifically identified to you, twice now. I'll remind you of the forum guidelines:

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Avoid any form of misrepresentation.

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Who said that was unreasonable? No, but its consequences for our species does change. Mountains and oceans cease to be meaningful barriers.I meant what I said. The geographical separation of our populations is decreasing. I'll address that post shortly. The long and the short of it is, we don't largely disagree.

I'm not concerned about it, per se - I don't think the West has the monopoly on really excellent genes, although I do enjoy the capacity to consume dairy products as an adult - it's just important to recognize that it is happening, because the alternative smacks arrogant species-centrism. "Oh, humans are so great, we've conquered natural selection."I realize that I'm putting forth an argument that typically is a prelude to racism - "oh, we have to save the West from being outbreeded by the darkies" - but I absolutely do not mean it in that context, of course. I think you're exactly right. Shared cultural knowledge fills a similar role as DNA - a way to pass on adaptations past the death of any one individual. It's why, in my view, the last step of the scientific method - sharing your results - is by far the most important.

Yes. I understand now what you are construing as a selective force. I am just not convinced that it constitutes one. We may just have to settle for respectful disagreement here. That's the $6 million dollar question, isn't it?
You seem concerned that we are losing Darwinian fitness in the west relative to UD countries. The current data definitely support that position, I agree. I am just not sure it is a cause for much concern given the other factors I can see coming into play which will have differential influences on whole populations. Despite our currently lower fitness, I predict that most our genes have pretty good odds of survival just based on where we live. And I still claim that reduced fecundity and delayed reproduction can be adaptive under various scenarios, particularly group selection - and group selection is really what humans are going to be facing from here on. Our survival as individuals (and the alleles we carry) is far more likely to be determined by the group we belong to, than by ourselves as individuals.So the only remaining 'bone of contention' is your definition of selection : But changes in gene frequencies can occur by random drift, without selection, as you well know I am sure. Don't you see any problem here?
Leaving the mechanism aside for a moment, you are still inferring selection simply by differences in rates of reproduction. That's your evidence, right? I have pointed out that both reduced fecundity and delayed reproduction can and have evolved naturally in various lineages. Might you explain how this is possible if reduced reproduction alone is to be considered sufficient evidence of selection acting against a sub-group? By this logic, every lineage should evolve to reproduce faster and faster and earlier and earlier to their physiological limits. We don't see this. We see higher organisms headed in exactly the oppsite direction.I will suggest that both reduced fecundity and delayed reproduction are traits that will highly adaptive for the human race to evolve in coming generations. We should expect to see them favored by group selection in future generations.

Hey, can this be possible?
Virtually complete agreement?*snap* Fizzzzzz. glug, glug (gulps beer)

Because that isn't reduced reproduction. You're conflating two entirely seperate things - strategies such as smaller brood size or strategic delays in mating to increase offspring survival, and overall change in population size.The strategies you mention wouldn't be successful if they didn't result in population growth for the offspring of those individuals. Halving your brood size, for instance, isn't evolutionarily advantageous unless your offspring have a substantially higher chance of survival to adulthood as a result. Reducing fecundity is only a successful strategy if it increases your population growth. In the case at hand, it demonstratably does not.

Reduced fecundity is not reduced reproduction?
Fecundity is the total number of offspring produced in an organism's life.
How can you possibly evolve reduced fecundity without reduced reproduction? No, you are the one confused and talking about two things I never mentioned. Firstly, fecundity is the not the same as brood size - the latter is simply the number of offpsring produced in a single bout of reproduction, not the lifetime. Secondly, a 'stategic delay in mating' is not the same as 'age at first reproduction', which is the age at which the first offspring is produced. For example, females of many insects mate once and store sperm for their entire lifetime, producing offspring much later. Mating can occur at any time - it's the physiological cost of producing the offspring that has a much bigger impact on life history. In semelparous creatures, they die. Just so we're clear, the *life history traits* I mentioned (not strategies - that's a term for behavior) were :1. evolution of reduced fecundity (fewer offspring in the lifetime).
2. evolution of delayed onset of reproduction (later birth of first offspring).I refered to these life history traits because they are analogous to the current trends that you identified as reducing human fitness in western countries relative to UD countries. You concluded that our slower population growth was evidence our genes were being selected against. I disagreed and said I thought it was simply evidence of slower reproduction and that there was no evidence of any selection. You said that because our genes were being replicated more slowly, that was evidence of selection. I said you can't define selection like that.Now I am pointing out that many lineages, over evolutionary time, have actually evolved reduced fecundity and delayed onset of reproduction.
I don't think that is disputable. Higher organisms reproduce at later ages and produce fewer progeny per individual.So here is the question again. If slower population growth (produced by summing the reduced fecundity of many individuals and their waiting longer to reproduce) is evidence of negative selection against that population, by your definition of 'selection', then how can either of these traits possibly evolve? They are, by your definition, evidence of selective disadvantage and can have no advantage. And yet evolve they did.They only answer is that selection CANNOT be adequately defined the way you have defined it. Selection has actually favored reduced fecundity and delayed onset of reproduction independently in many lineages over evolutionary time. Otherwise, an elephant would reproduce as quickly as a house fly. Reproductive rate is just one life history feature of an individual, (or a demographic statistic of a population - we must distinguish these) that has to be interpreted within the much larger context of the species' adaptive topology, sensu Sewall Wright. Faster rate of reproduction is not always going to correlate with greater fitness in all contexts. You have now abandoned brood size and returned to fecundity, but now you have made a completely paradoxical statement.By definition, reduced fecundity leads to a lower rate of population growth. It CANNOT, by definition, possibly increase population growth. However, it can increase population *survival*. The only way reduced fecundity can evolve is if populations with lower rates of reproduction are more sucessful in surviving than populations with higher fecundity. They end up *leaving* more offspring because they are *producing fewer*, but perhaps these fewer are larger, more competitive, etc. etc. (More good analogies to western humans here).So finally, how can we possibly say for sure that reduced fecundity and delayed onset of reproduction are not being selected for in humans today? We can't. In human societies, group selection could easily favor populations with lower reproductive rates and selection could already be acting against those UD countries with high population growth rates. For example, the civil wars in Congo and Darfur are examples of strong group selection occurring right now that are severely reducing average fitness in some high RR populations.As RazD would say, 'Enjoy'EZAbE for new subtitleThis message has been edited by EZscience, 05-06-2006 01:35 PM