Is evolution going backwards?

Hi contra.I've been trying (vainly) to follow this discussion as it touches on areas of particular interest to me, but have completely lost the thrust of the argument.Would it be accurate to characterize your initial question as: "Does the increase in lethality of endemic warfare among humans currently constitute a selective pressure on human evolution?"?I guess I'm getting confused because it seems you and crash have gone off on tangents concerning the evolution of endemic warfare itself, and how that relates to competition, etc, rather than the question you initially raised. Please correct me if I've inadvertently mis-stated your question, or the topic of discussion. Thanks for your help.

I've only just seen this thread, and I'm at least as confused by it as Quetzal. A couple of points that may or may not be relevant, since I'm not sure what is relevant:1) Currently, death by violence is a minor component of human mortality: 1.3%, according to the WHO, of which 0.4% is caused by war. In contrast, 32.5% of human mortality is caused by infectious disease. I don't know if this number was the same in the past, but at present it is unlikely that war is having a signficant direct effect on natural selection in humans. (I'd also be surprised if this were an unusually high fraction compared to other animals, but I haven't seen any numbers.)2) Humans in economically developed countries are less likely to pass on their genes than those in poorer countries. This is just a fact.3) If there are no adaptive responses possible to violence, then all violence does is reduce the effective population size slightly, and therefore increase genetic drift slightly. Since the current human population size is enormous, the effect today of violence on human genetics is tiny.

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Would it be accurate to characterize your initial question as: "Does the increase in lethality of endemic warfare among humans currently constitute a selective pressure on human evolution?"?

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No, for several reasons, which I will come back in a second.Forget INCREASE in lethality, think only of the persistance of warfare through various historical epochs. My question is, "what effect does such a sustained activity have if any?" Candidates for answers to such a question might include a decrease in variation, for example.

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I guess I'm getting confused because it seems you and crash have gone off on tangents concerning the evolution of endemic warfare itself, and how that relates to competition, etc, rather than the question you initially raised.

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IMO the terminaological problenm is that competition is an excessivley broad term, mostly for ideological reasons.so a chimp say competes with other chimps dircetly for their food.
But a chimnp also competes with leapords but avoiding being prey, the result of the chimps success perhaps being the leapords death
If the chimp catches a small rodent it has also competed with the leapord for food, but in very assymetric degree
or, a chimp might compete by violence with another chimp for a food source or a mate.All these can rightly be termed "competition" but the term "competetion" can imply all of them without distinction. As a dialectical materialist, I try to cut away from the abstract term and towards the physical realty I am trying to address.I am arguing that the mode of warfare is a specific mode of "competetition" most akin to predation. I see this as being equivalent to a species that has adopted cannibalism, possibly as a result of hitting carrying capacity.I think tha humans have in effect been editing their own genome in a sustained manner for a long period of time. A large number of people were removed from the gene pool before being able to pass on their genes, more so than would have occurred if we were only influenced by environmental pressues, or mate competition. So I ma suggetsing that warfer is de facto a self-imposed measure of selction, and asking whether this source of selection is any way significant.

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1) Currently, death by violence is a minor component of human mortality: 1.3%, according to the WHO, of which 0.4% is caused by war. In contrast, 32.5% of human mortality is caused by infectious disease. I don't know if this number was the same in the past, but at present it is unlikely that war is having a signficant direct effect on natural selection in humans.

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I'm noty particualrly interested in post-Industrial values, but in the persistence of the effect over the last 6000 years.

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2) Humans in economically developed countries are less likely to pass on their genes than those in poorer countries. This is just a fact.

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I still find that implausible; even if the genes in the undeveloped world are likely more likely to be continued overall, I think its mistaken to think that the individuals genes are likely to be so.

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3) If there are no adaptive responses possible to violence, then all violence does is reduce the effective population size slightly, and therefore increase genetic drift slightly. Since the current human population size is enormous, the effect today of violence on human genetics is tiny.

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Yes IF that is true but that has not been shown. Further, I'm much more interested in this as a sustained phenomenon, in societies that were substantially less numerous.

Ahh, thanks for the clarification. Now I can follow the arguments a bit better.One thought: have you considered comparing the effects of warfare vs the effects of things like the Black Plague (either the Mongolian epidemic of 46 AD or the European epidemic of the 14th Century)? It would seem to me that although warfare has been endemic for much of humanity's short history, as a percentage of population effected disease has had a much greater impact genetically. It may be that eliminating one or two percent of each generation through warfare would have an equivalent effect to eliminating 70% (Mongolia) or 30-50% (Europe), but it seems counter to my understanding of population genetics. A random sampling of a "few" individual members of a population has less effect on genotype than elimination of a large fraction of a population (WWI less the Russian revolution @ approx. 22,000,000 out of a global population of 1,600,000,000, compared to elimination of 25-30,000,000 out of a European population of 100,000,000). Admittedly, the comparison might not be valid - you'd have to break down the WWI figures by geographic location. However, I think that elimination of a substantial fraction of a population with limited geographical distribution over a limited timeframe would have a greater impact than the elimination of a small fraction of a widely distributed species over a long timeframe, genetically speaking.Still, an interesting idea. How would you test it?

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I'm noty particualrly interested in post-Industrial values, but in the persistence of the effect over the last 6000 years.

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Ok. So what level of warfare are we talking about here? The last 6000 years are a period of rapid increase in the human population, large changes in diet, and the advent of epidemic disease as a major factor in human mortality. Is there any reason to think that warfare would have a significant role in changing selective pressures, given all of the other things that happened during that period? Ancient warfare is hardly my field, but I note the following (from http://www.santafe.edu/...ations/workingpapers/98-10-088.pdf)
"Before leaving the Neolithic it should be pointed out that while
warfare appears somewhere in the historical sequence of most world
areas, it is not omnipresent in the archaeological record of the
period. The overwhelming majority of Neolithic residential sites
in the world are not defensively located, they are not surrounded
by stockades, and they have not been burned or pillaged.
Manifestations of warfare in rock art, burials, skeletons, and
weaponry are rare rather than common. The number of well-documented
cases of endemic, intense warfare at the regional level
are few and far between. In contrast, extensive regional surveys
and excavations have exposed long sequences in virtually every
corner of the globe where material manifestations of war are
absent or highly localized and episodic. War was more the
exception not the rule during the Neolithic."If warfare was not a major force in the neolithic (which here means the period that ends with the development of complex societies), then you're talking about the last 1000 - 4000 years. I'd be interested in seeing any numbers on the overall effect of warfare on mortality during this period, but my initial guess is that it's unlikely to have been a major selectional force, given how brief it is (genetically speaking).

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I still find that implausible; even if the genes in the undeveloped world are likely more likely to be continued overall, I think its mistaken to think that the individuals genes are likely to be so.

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The average person in the undeveloped world has more children who survive to reproduce than does the average person in the developed world. That has to be the case if the population of the undeveloped world is increasing faster over multiple generations. Unless there is a much larger variation in how many children people have in the poorer world, this will mean that people in the developed world will on average pass on fewer of their genes. While it's conceivable that there is a much larger variation in number of offspring in poorer countries, I don't know of any reason to think that there actually is. (The one factor that I can think of that might distort things in a significant way is AIDS in Africa, which is causing a high enough mortality amoung young adults that the probaility of passing on genes might be affected.)This message has been edited by sfs, 02-07-2005 11:00 AM

Firstly on disease:Yes, the proportional impact of disease may well completely wipe out an notional effect originating from warfare. That would indeed be a reasonable answer to the query. On the other hand, I would be interested to know to what degree desease fatalities increase with increasing populations and density, becuase while diseases may cause fataltities that open up opportunity spaces, dapatations to disease are largely invisible. Thus gross morphological changes must be impelled by influences other than disease.Sfs, I think the neolithic can be ruled out. I'm definitely in the camp that sees neolithic society as essentially not exhibiting warfare. Conflicts yes, but organised significant warfare, no. The advent of urbanised socities appears appears to seen trigger the advent of organised warfare, to the point that our earliest records are essentially dynastic military claims (narmer pallette etc).However I still put this back at about 4000 BC as this is the point at which rulership develops as a political concept. Rulership entails the maintenance and mobilisations of military force as a necessary prerequisite to its existance. And the wars of the period are often ones of extermination, as we see reflected in the bible. In later periods the inevitable imperial projects brig about massive urban improvement but also a huge increase in the scale and intensity of warfare, which still exhibits large-scale slaughters of the populace captured cities.The Romans of course also dealt with multitudes of migrating barbarians, and both these groups had a sort of take-no-quarter approach. The migrations themselves are a massive movement of human population and created huge geographic zones of serious warfare.Now a comment on the scales of populaiton here. World War One is mentioned above, but as a recent trailer has ben maintaining, the loss of English life was proportionally greater in the civil war than that WW1. In Japan, the military samurai class reached as much as 10% of the whole population, the Western feudal nobility achieving about 6-8%. While the turnover among the Samurai is pretty low, it is not in the European case, and of course there are large numbers of combatants and civilians beyond the 10% also affected by the fighting.When Rome fought the Gauls, probably much more than 10% of the populace weree combatants, probably something in the region of 20-25%; again, the various battles and massacres must have accounted for a sizable chunk of the local population. The Pechenegs were a significant ethnic power in the Black Sea region until virtually extirpated by the Byzantines. It seems to me that the classical sources are full of accounts of whole cities and provinces being depopulated, whole ethnicities exterminated.In addition to all of this, there is the necessaity to do some killing merely to maintain the social order of urbanised societies, and so this period also sees the universal developement of corporal punishment as a means of state power. But of course we have very much less information about such judicial killings than we have of military adventures.So my point is, before the advent of industrialism, a significantly greater proportion of the populace would be engaged militarily, the absolute population would be much much smaller, and the intensity in terms of population impact would, it seem to me, be rather higher. And again, this is activity sustained over a large geographic region for a long period of time. It would in fact be surprising to me if there were not impact at all.This message has been edited by contracycle, 02-08-2005 05:48 AM

I ran into this article while looking for some correlation between warfare and genetics. It looks like you may be on to something. There appears to be a direct correlation between frequency of a particular allele of the human D4 dopamine receptor (the 7 repeat, or 7R allele) and the prevalence of warfare in certain societies. Thus we have a gene-linked behavior that can be traced (at least in some cases) that seems to positively correlate to the level of inter-male and inter-communal violence. The article (well worth the read) argues that such an allele is subject to positive selection (and explains why). IOW, at least in certain societies, the allele that is linked to ADHD in modern societies may have been selected for due to warfare in Neolithic societies. A fascinating read. (You’ll also enjoy the thought that this correlation seems to contradict Cosmides and Toomes EvoPsych contention that genes don’t have significant influence on behavior). Harpending H, Cochran G, 2002, In our genes PNAS 99:10-12

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In a preagricultural world of hunters and gatherers, males with an advantage in face-to-face competition would have enjoyed a limited advantage, perhaps being favored only in those niches where periodic resource abundance allowed male competition to flourish elsewhere new ecological circumstances led to transient plenty as on the Great Plains after the introduction of the horse. Otherwise they would have been disadvantaged, especially because there were more of them. But the advent of gardening technology freed males from subsistence work and, in the new social environment of display, aggression, and male coalitional violence bearers of 7R may have flourished, accounting for the evidence given by Ding et al. (3) of the recent increase in frequency of the allele. Finally, as polities emerged that suppressed the system of local anarchy, population growth occurred, land became scarce; agriculture became more labor intensive; and men were again forced into work to provision their families. The archetypes in the literature of anthropology of dad hunter-gatherers are !Kung Bushmen of southern Africa; the archetypes of labor intensive farmers are east Asians; and the archetypes of local anarchy are Indians of lowland South America like the Yanomamo. It is probably no accident that two of the best known ethnographies of the twentieth century are titled "The Harmless People," about the !Kung who have few or no 7R alleles, and "The Fierce People," about the Yanomamo with a high frequency of 7R.

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The above is from a commentary on the PNAS article: Ding YC et al, 2002, Evidence of positive selection acting at the human dopamine receptor D4 gene locus, PNAS 99:309-314You should probably read both articles to get the full picture. Although this doesn’t really answer your question, it does provide at least some support for the idea that warfare has had a genetic effect (or genetics have had an effect on warfare ).One additional comment. You said: I’d actually put organized warfare somewhat further back, in the Late Neolithic. Evidence of fortifications from Jericho (dated around 6000 BC) and Catal Huyuk in Anatolia (dated around 7000 BC) would push the advent of something resembling organized warfare back well into pre-metallurgy times (dates rounded to nearest ‘000 for convenience). At least raids, etc, must have been common enough to justify the effort in building fortifications.As to the disease vs warfare. I still think that in most cases disease has had a more significant impact on genotype than warfare. Although there are numerous cases where wars of extermination have been fought, most warfare during our formative years as it were appears to be more of the raid type rather than extermination; for females, for resources, for dominance, etc. As a proportion of the population effected, even if a large percentage of adult males engaged in battles, the casualty rates would be small. Even in some of the most famous battles among some of the most militaristic of Bronze/Iron Age societies (say, Leuctra), that resulted in the slaughter of the opposing force, the majority of the population itself was unaffected. Although such cases as the massive destruction caused by the rampages of Tamur the Lame and others may have had a significant effect on a particular city, the overall effect on regional populations of even the most badly devastated areas were limited to those cities, leaving the population itself unaffected.
Contrast this with disease, which not only wipes out males or the population of one city, but can effect entire continental populations at one go. It may simply be that disease has a much more obvious selective effect. If so, it may be difficult to discern the selective effect of warfare as it would masked by the much more common (and devastating) effects of disease. I don’t disagree with your basic point here. However, I think you’ll find that early warfare (at least if we use modern hunter-gatherer, pastoralist or swidden agriculturalists as a basis, plus the record of the Mesoamerican civilizations), was limited in duration and extent. Most primitive conflicts were essentially raids (for cattle, for women, for food). More advanced societies like the Mesoamericans, pre-dynastic Chinese, or the organized city-states of the Fertile Crescent were interested in dominance, slaves, etc. IOW, although the populations were smaller the objectives of the conflicts would (IMO) tend to limit the actual impact. You can’t make a slave out of a dead body. Prior to industrialized mass slaughter, with a few exceptions, the intensity of the warfare was lower overall. Whether or not this means that warfare did or did not provide a selective pressure (essentially random) is a question I don’t have the answer to.

Sure. I believe this usually falls under the heading of "genetic drift." And you're exactly right that there's a possibility that genetic drift could have a stupendous effect on a population's genetics.What effect would that be? Since the drift is random, it's not possible to predict. What usually happens to that population is a decrease in disease resistance, or things like that. Monoculture populations are very vulnerable to disease.If a human population was able to restrict its reproduction with other groups, and somehow began eliminating genetic variation within it, certainly we would expect to see a decline in disease resistance. And we have, I believe. But it really takes a lot to close off a population like that; warfare usually has the exact opposite effect. You know, soldiers rape women, or take slaves, or the like. And humans find exotic features attractive, often. We have a lot of behaviors to counteract that "inbreeding" problem.You've raised some great issues, regardless of the terminology. I can see what I believe is your point - that the genocidal aspect of warfare often eliminates genetic lines wholesale, and reduces diversity of populations. But I hope too that you can see how other aspects of war might have the opposite effect of introducing new genetic lines into other populations.It's too complicated for me, I guess. I literally have no idea what effect warfare would have.

Thanks Quetzal...thats some great stuff.I had previously thought that warfare was affecting our cultural evolution and had little but perhaps a drift effect on genetic makeup. Obviously warefare has an effect on some genetic markers.I agree with you that the most profound genetic changes in humans come in response to disease. My background is in microbiology, so perhaps its an innate response, but it seems to me that the history and sheer number of disease interactions outweigh the effects of warfare.To go back to the original question, I risk repeating myself from a previous thread. I don't think evolution is going backward. To many evolution is "differential reproductive success" in "adaptation to local environments". Any perceived directionality comes from our active minds trying to discern a pattern that may not be there.What is exciting to me from your information is that our cultural evolution seems to have a genetic effect that is relatable to overall behavior patterns in distinct groups. Great stuff to chew on!

You're welcome. Those are pretty neat articles, all told. The only question I have on the articles is that it's unclear whether the 7R gene effected cultural evolution or vice-versa. All we have is a correlation, albeit a highly interesting one. Yep. Disease is not only more widespread in area and effect, but actually does have a documented genetic component, esp. as concerns resistance and chance of survival. Unlike warfare. To me, the effect of warfare as actually practiced through history would seem to fall somewhere between drift and the kind of "sampling error" you find in founder populations, for instance. I'm obviously open to contrary evidence. Well, I agree that it's really interesting to have a single gene we can trace to behavioral affect that is distinct in different, widely separated populations. However, again, I'm not clear which came first. This DOES kill the evo-psych contention that human behavior can't be traced to a single genetic marker, tho'. Wonder what Parsimonius Razor would say about it.

To be a significant warrior requires certain skills, training. The move from Warrior to Army adds the need for a support system, infrastructure in the form of armaments, logistics, planning, leadership, direction and supply.Disease on the other hand requires only something infectious and it need not be human or even infect humans.

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Aslan is not a Tame Lion

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What usually happens to that population is a decrease in disease resistance, or things like that. Monoculture populations are very vulnerable to disease.

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Right - that was sort of my starting point. That is, IF
- war is a significant cause of death, and
- its effect tends to reduce genetic variation, then
- we might be said to be becoming "less fit" as a species as a result of military competetion.And thus, evolution might be said to be "going backwards" - that is, as time passes we become less fit on a species level, and more vulnerable to a single disease (or other) catastrophe.

I think that's a reasonable point. But I disagree with your second premise; it seems to me that war increases diversity via sexual recombination of individuals who otherwise might not have mated. Armies rape; that's gene flow between otherwise separate populations.Of course, the majority of deaths in warfare have been from disease.I dunno. It's all too complicated. I see factors that increase diversity; I see factors that reduce it. I can't say which are the more prevalent.

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Right - that was sort of my starting point. That is, IF
- war is a significant cause of death, and
- its effect tends to reduce genetic variation, then
- we might be said to be becoming "less fit" as a species as a result of military competetion.

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War might have reduced genetic variation for two reasons.
1) It might have reduced the population significantly, so that genetic drift increased. While war may have been a major cause of death, I don't know of any reason to think that it reduced population much below the carrying capacity of the environments humans were inhabiting, so I doubt it had much effect on drift.
2) If it introduced strong selective pressure. I find it quite hard to believe that war would produce such strong selection that there would be more than a tiny reduction in overall diversity.