For the Good of the Species

Peter Turchin

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Yesterday the top science journal Nature published a bomb-shell article, but my feeling is that biologists haven’t yet realized the explosive nature of the report. I’ll explain, but first we need to make a lengthy excurse into the history of the group selection idea.

Whether group selection is an important evolutionary force, or not, is a highly controversial question in evolutionary science. A substantial proportion of evolutionary scientists still think that it is not. The stakes are high because I and many other proponents of Cultural Evolution think that group selection (or, as we prefer to call it, multilevel selection—selection acting simultaneously on individuals and groups) provides the key to our understanding of the evolution of human ultrasociality—the capacity of human beings to cohere and cooperate in huge societies (millions and more of people).

Actually, the best theory that enables us to understand ultrasociality is “Cultural Multilevel Selection” (see my book Ultrasociety about how human societies evolved from small bands of hunter-gatherers of 10,000 years ago to the huge megasocieties of today by the process of multilevel selection acting on cultural traits). I tend to agree, to a certain degree, with the critics that genetic group selection is not a commonly encountered evolutionary mechanism in the field, although in the past it was clearly hugely influential. Because how would, otherwise, we get multicellular organisms? And genetic multilevel selection provides the best explanation, in my opinion, of other “major evolutionary transitions”, which include, in addition to multicellular organisms, such epochal events in biological evolution as the rise of the eukaryotic cell and social insect colonies.

The first proponent of genetic group selection was Charles Darwin himself, who wrote about it in his second major book, The Descent of Man and Selection in Relation to Sex, which was published 12 years after On the Origin of Species. Darwin’s ideas on group selection remained very influential for about a century. One of his well-known followers, the English biologist V. C. Wynn-Edwards, became an advocate of the idea that individual behaviors can evolve not just because they help individuals, but for the good of the species as a whole. In other words, Wynn-Edwards and other adherents of what later became known as “naïve group selectionism” thought that evolution could operate at the level of really large groups—whole species.

I attach the label “naïve” to these views because arguments of Wynn-Edward and others relied on simply pointing out the importance of a trait at the level of a group (or a species) without considering carefully how such traits affected individuals. Incidentally, this is why I prefer “multilevel”—because our current theories explain much better the evolution of behaviors that have opposite effects at different levels (e.g., favor the group but at the expense of individual fitness). It’s not a trivial question, and it requires non-trivial math to figure out when either the group-level or individual level force dominates.

In any case, by the 1970s the tide turned against group selection. The key thinker in this reversal was George C. Williams, and his ideas were popularized by Richard Dawkins in his wildly popular book The Selfish Gene. When I studied biology in graduate school in the early 1980s, nobody believed in group selection, apart from a few “heretics” like my good colleague and friend David Sloan Wilson.

In the last decade or so the tide started turning back. In particular, the hugely influential social biologist Edward O. Wilson (no relation to David) “flipped” from a critic to an adherent of group selection. But many, if not most, continue to reject it (for example, the geneticist Jerry Coyne or the evolutionary psychologist Steven Pinker).

Getting back to Darwin, it is not a coincidence that his second major book, in which he wrote about group selection, has the subtitle Selection in Relation to Sex. Here’s a fun example illustrating this connection, which I have recently used in a lecture in my cultural evolution class last week.

Source

Many of my readers know that there was a species of deer in which males grew astoundingly huge antlers—the Irish Elk. It roamed Eurasia from Ireland to China during the Pleistocene, and went extinct around 8,000 years ago. Why did Irish Elk males sport such spectacular antlers?

The reason, as Darwin explained, is the sexual selection. Every fall male deer (including elk and moose) participate in jousts, with winners getting to mate with females. The larger is the weaponry that you bring to the contest, the better are your chances of winning it, which means mating and passing your genes to the next generation. So natural selection favors males with larger antlers (as they say, “size matters”).

Note “larger”, not huge. What’s important is not an absolute size, but a relative advantage. In the land of small-antlered, the medium-antlered elk is king. But then, in a few generations, everybody has medium-sized antlers, and so to get ahead of the crowd you need large ones. And so on. As the arms race continues, eventually only those elk with gigantic racks have any chance of reproducing. Growing huge antlers is energetically expensive, and a huge risk—whether getting tangled in the branches, or not being able to escape predators due to their heavy weight.

If only elk males could get together and agree to put a limit on the size of their antlers… Everybody would be much better off.  Instead, each individual strives for advantage, resulting in a collectively suboptimal outcome. One could say that the Irish Elk went extinct as they literally collapsed under the weight of their antlers.

We don’t really know why the Irish Elk went extinct. Perhaps the reason was the run-away competition between males, resulting in unsustainably gigantic antlers. Or there could be another reason. And here’s why the Nature article, to which I referred in the beginning, is so interesting: High male sexual investment as a driver of extinction in fossil ostracods by Maria João Fernandes Martins and co-authors.

Ostracods are small crustaceans, shrimp-like creatures that protect themselves with bivalve carapaces (shells). These shells are well preserved as fossils, and so we know quite a lot about their evolution.

The inside of a right cytherocopid ostracod valve

Fernandes Martins and co-authors analyzed the paleontological data on 93 species that lived in the area that is now Mississippi state between 84 and 66 million years ago. They assessed the strength of competition between males by how much males invested in reproduction, which you can tell by the shape of the shell (e.g., how long it is). Basically what they did was similar to estimating the strength of between-male competition in deer by looking at how large their antlers are. Then they did a statistical analysis on how the strength of sexual competition affected the probability of extinction of the species.

They found that the probability of extinction of the species in which males competed most intensely was ten times higher than in the species in which males did not compete very hard. This is a huge difference, and it lends credence to the idea that the Irish Elk went extinct because of intense between-male competition necessitating high investment by males into growing big antlers.

The implications of the study by Fernandes Martins and co-authors, thus, go far beyond an obscure group of shrimp-like organisms. What we have here is a clear example of multi-level selection. The individual level selection forces each male to invest into sexual competition as much as possible. But at the species level, those species in which between-male competition goes too far, has an order of magnitude higher chance of going extinct. As a result, most species find themselves at an intermediate level of male sexual investment.

It’s interesting that the authors of the Nature article do not even mention multi-level selection, nor do they talk about the broad implications of their study, as I have done in this blog. They are either not aware of them, which seems unlikely, or they simply didn’t want to enter the highly contentious debate about group selection. Equally interesting, Nature apparently did not deem this study to be important enough to devote a News-and-Views article to it. But I think that the implications of the study are explosive. If Wynne-Edwards were alive, he would feel vindicated.

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Juan Alfonso

Hi, Peter

There is clear link to ultrasociality, right? Males can compete intrasexually through any kind of traits, as long as they are conspicuous. Pro-social traits and behaviors can be quite conspicuous traits (see the example of arabian babblers in Amotz Zahavi’s “Handicap principle”).

Big antlers are conspicuous, but they don’t provide any other advantages besides that. If there is a change in the environment, the males with this trait might be too handicapped, and the whole species might not have enough time, in terms of generations, to adapt to the new environment by reversing the size of the antlers, and/or “finding” another trait to signal male fitness.

On the other hand, there are traits that are both a conspicous handicap and useful trait (an example could be the necks of jiraffess). For example, in a time of environmental change, ultra-developed prosocial traits could enhance adaptation to the new situation. Hence: ultrasociality.

Juan Alfonso

Yeah, you’re problay right. However, signalling traits that are useful for survival could “use” sexual selection to “speed up” its evolution, and be shared in both sexes because of its utility. Male jiraffes fight with their necks. Females don’t do that, but anyway they inherit their fathers’ necks.

Elk huge antlers are the result of extreme inter-male competition for breeding. Less polygamous species can also benefit from sexual selection in a less sexually dimorphic way.

My point is that pro-social traits and intelligence could be an example of this. They are both present in men and women, and they are considered sexually and socially attractive for both sexes (see Geoffrey Miller’s “The Mating Mind”). So, under certain conditions, sexual selection might drive a species to extinction, or just the other way around into ultrasociality.

Francisco

Probably the key is managing to restrict the competition among individuals to environmentally useful traits at every level, IMHO. The problem is how to make sure we can implement that fairly at the group level.

Steve H.

I’m trying to reconcile the rapid adaptation and trait adoption which your cultural transmission model tied to warfare, with this arms-race extinction loop which ties with inter-elite competition. If every individual is their own within-group set, it seems some are better at taking a group as an extension of their own agency. I’m unclear within-group sorting can be simply identified as distinct from between-group competition.

The nearest I get are co-operation matrices, where two species can co-exist as long as each has a competitive advantage on a resource necessary to both. What seems like a detriment can become a resource. Russia cannot be defeated because of high adaptation to cold, in a conflict situation they can endure better than the competition, the competition depletes resources from long supply lines and lower efficiencies, and then Russians come back to the open and kick them out. So what seems like a detriment becomes a resource to be exploited.

Likewise with China, what seems like overpopulation means China cannot lose a war of 1:1 attrition. But does this lead elites to try to trigger events for their favor? “Never get involved in a land war in Asia.”

Putin recently said in effect that Russia has no use for a world without Russia. Dominionists in the American military not only don’t fear death as long as they go to heaven, some believe that a triggered apocalypse will give rise to an ideal state or condition. Are these adaptive responses? They seem to be culturally exclusive and not adaptive. Once again, how to distinguish within-group v between-group conflict gets murky.

Iuval Clejan

Until we have a mathematically rigorous and empirically measurable definition of group fitness, it makes no sense to talk about group selection. I am working on a paper (it will take several months) that shows how group fitness is an emergent property (in a well defined mathematical way) of populations that cooperate in certain precise ways, and it has nothing to do with the Price Equation (as far as I can tell). In other words, not every population of interbreeding individuals, or even cooperating individuals, has such a fitness function. Since I am not in the field and have no institutional backing (I was trained as a physicist and have left that field a long time ago), I could use some help in getting this published. Can you help? I am also hoping to enlist MacElreath, through a colleague.

As far as the Ostracods and Irish Elk are concerned, we can think of traits which benefit individuals at the expense of the group (or even without benefitting the group) as freeloading traits. I am still working out the math to see if I can predict certain things like the equilibrium value of such a trait.

Juan Alfonso

Hi, Luval

That sounds very interesting!

I would like to know what you think about an emergent property in certain human groups. Namely, the male:female ratio. This is an example taken from Marvin Harris books about the Yanomami tribes in the Amazonas.

Apparently, yanomamo bands tend to favor male births over female births. They use female infanticide to bias the ratio. Since this male-bias can give a band a competitive edge over neighboring bands, at least when it comes to inter-band warfare, I think it could be considered an emergent group trait. Sex is an individual trait, but could the ratio be considered a group trait?

Of course, I’m talking about a cultural trait, since there is a lot of inter-band breeding between the yanomami.

Barkeep

Peter, is their evidence in the article.or others that populations correct rather than go extinct?
Are humans having a male aggression correction right now?

Walt Socha

As I read this article, I kept thinking of the phrase “toxic masculinity”…

Edward Turner

Meaningless cliche. Too much of anything is toxic and I can easily make the argument that material over-consumption is caused by toxic femininity.

Nobody does because that would be sexist and it’s only true in the statistically ‘average’ sense – it’s not a fact that applies to every man or woman and in some cause you can switch the logic around.

Obsessing about the stereotypical male trait – competitiveness – is also sexist and doesn’t intellectually advance the discussion.

My first thought reading this article was Military Industrial Complex, which is a property of the state, not of any particular individual, male or female. This is an interesting statement.

Edward Turner

Feminists might like to claim the Military Industrial Complex is caused by men – or male competitiveness and desire to dominate – but if Multilevel Selection Theory is correct, both men and women are equally culpable. For the state to operate efficiently you have to have both sexes pulling in the same direction. Those that don’t get eliminated.

Iuval Clejan

Barkeep, I am not sure there is a distinction between correction and going extinct. The mechanism of selection is survival of the fittest, so one population is outcompeted (goes extinct) by another, fitter population. Sometimes coalitions can form where two or more populations have equal maximal fitnesses and they all survive.

Anita Marie Lewis

Yascha Mounk, recently seen on The Open Mind with Alexander Heffner, in talking about changes in American democracy used the phrase,
“…showing a more sophisticated use of the uniformity of causation would be to the (fill in appropriately) benefit.”

Your analyses does this for me. Thank you for being.

Michael Popov

Peter,
My experience in epigenetics and CRISPR cas9 crypto suggest that “molecular multilevel selection ” could be understood as some useful simplification also. Renin -expressing cells, for example, do not fully differentiate but retain some kind of group molecular memory,which enable them to regenerate injured gloumeruli to control blood pressure,etc.

Michael Popov

Peter,
My example may demonstrate how evolutionary biology can be applied to chemistry of renin cells ( immune defence mechanism) and I may suggest that molecular cooperation with group memory may arise as a result of group selection ( in the form of Wilson-Sober theory, kin selection ( Frank,Bourke) or even multilevel selection theory (?). Moreover, because a common way to quantify group selection in biology is by applying the PRICE equation ( Nature,227,520-521,1970), such sort of simple math can be used in chemistry as well…
At least, when I was “orbital” anthropologist ( Oleg Gazenko’s space anthropology workshops at IBMP ) we did it.

Doug Jones

The one instance of species-level selection that a lot of old time individual selectionists (Williams, Maynard Smith) were prepared to accept was selection against asexual reproduction, which massively benefits the asexual individual in the short run, but puts long-term lineage survival in danger. The idea was that transitions from sexual reproduction to asexual are rare enough not to overwhelm species-level selection against asexual lineages. But the Fernandes Martins paper suggest that the phenomenon may be more common than that.

Regarding group selection in humans, here are some thoughts on how “ethnic group selection” relates to ethnocentrism: http://www.ehbonline.org/article/S1090-5138(16)30373-7/fulltext

Doug Jones

One further stray thought: The heritability of sexual dimorphism (in humans at least) is very low. Rogers and Mukherjee (https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1558-5646.1992.tb01997.x ) show that selection for stature will work 60 times faster than selection for dimorphism in stature. (This fits the evidence: human populations, which have had 10,000s of years to diverge, differ a lot in stature, not much in level of dimorphism in stature). Maybe this makes dimorphism a good candidate for species selection, because within-species selection isn’t very effective.

Peter van den Engel

Yes, multi level groupselection is a natural physics function of the whole, as it is in its energy behavior in time.
Since the source is a ‘thermo dynamic’ law, involving temperature and food: to find new energy before it’s lost in time. This is not primarily genetic programming/ although genes back react to it, because they program biology mechanics, creating possible behavior in the wider environment of temperature and food, which is its end equation.

The sum of wanting an offspring as large as possible creates a difference in male and female individuals in the group, because one male can have more wives at the same time/ while one female cannot have more men at the same time, baring their children.
So this natural physics arithmatic already foretells there will be infighting male: to extinct other males, otherwise it would not be able to function like this.
It is a group selection mechanism to begin with.

The fact this is later being perceived as individual male behavior, created by his (selfish) genes alone, is understandable because it is the first thing you notice in behavior/ but it completely overlooks its origin.
It’s not even that men are more aggressive than women/ but the back reaction to this ‘thermal’ law, which is a natural physics energy group selection mechanism to begin with. Not as if it was a conscious selection made by individuals in the group, as a function of their group selection deciding apon it.

Because the selection method itself was limited to a male weapon, being only effective regarding the same species biology, it created a spiral in genetic programming, because many females transponded the same mesage, leading to overweight in something which was not able to compete with other species (predators) and probably made the species vulnerable for bacteria or virusses the group had no experience with. It led to inbreeding.
So in the end it was contrary to its objectives. You could say as a result of individual exploitation/ but it was the type of chosen group selection.

tongal

Hypothesis:
Sexual selection —> masculinization of males —> (physical and/or psychological) masculinization of females as a by-product —> reduced fertility of females —-> extinction.

Implications:
Are human societies at that point?

Ross Hartshorn

What evidence I have seen published on the matter, indicates that average male testosterone levels have been falling over time, not rising (e.g. brow ridge was one proxy used to estimate this). So I don’t think we have reduced fertility of females for any reason relating to biological masculinization.

Now, one could argue that social roles for women becoming more like men’s, is resulting in fewer births per woman, which has unquestionably happened, but only in the last 50 years or so. It’s more likely, though, that this is related to medical advances (esp. antibiotics) resulting in fewer child deaths, such that you need fewer births to get adult children (and grandchildren). So, again, no evolutionary cost there.

Now, if some trait in a woman makes her more likely to forego having children altogether, in the last 50 years, then we would expect to see that trait start to decrease in frequency pretty rapidly. But that possibility is probably even more politically charged than the multi-level selection argument that Dr. Turchin discusses above, so I would not expect it to get discussed much soon!

tongal

I should have added this:
That scenario would have a synergistic effect with the hypothesis of higher #masculinity of older siblings ->
– Lower number of children per couple –> more masculine females in new generations –> reduced fertility… AND increased combativeness of women (increased #feminism).

Loren Petrich

As to the Irish elk / giant deer, there is a problem with the hypothesis that the male ones’ giant antlers caused their extinction. The oldest remains of them are some 400,000 years old, and they survived several interglacials before the Holocene. So they didn’t get their big antlers all of a sudden. The Irish elk were about the size of present-day moose, and their antlers were not much more massive than moose antlers, though they had twice the spread (from numbers from their Wikipedia articles).

One has to ask why the Irish elk went extinct while moose survived to the present. Though they survived a long time with their large antlers, those antlers may still have made them vulnerable to unusual stresses, something like the ostracods.

Peter van den Engel

Why moose have survived I suppose is likely because they lived in smaller groups in less furtile environment and their antlers were perveived as a token of maturity, not provoking a fight. The men had less wives, so there was less inbreeding and less molecular risk.

Vladimir Dinets

I think the most likely explanation is that moose lived in areas with much lower density of human population. They did, however, go extinct in much of their European range.

Peter van den Engel

You mean like the American buffalo, which actually was almost extinct thanks to the invention of railroads. People found it a good sport to shoot them from the window.

The irish elk was extinct 8000 years ago, when there was hardly a large human population available. So in this case it was not (just) human interference.

Vladimir Dinets

The Irish elk went extinct together with a lot of other large mammals; human hunting is the only possible explanation. See https://en.wikipedia.org/wiki/Quaternary_extinction_event

Loren Petrich

Multilevel selection may also explain why immune-system antigens vary in a species. If one variant becomes too abundant, then parasitic organisms can camouflage themselves by resembling it. These organisms can then make that variant’s owners sicker than average, reducing their numbers. This is the “kill the winner” effect, something that also maintains some species diversity.

Ross Hartshorn

I have seen a similar argument for why tropical forests have higher species diversity (of trees) than subarctic ones, basically the idea being that the more conducive the environment is to disease (warm and humid), the more important it is to be well away from your nearest conspecific (because many diseases specialize in one or a few species). So you can have subarctic forests dominated by one (usually coniferous) species, but jungles where looking around you don’t see a single tree within sight that matches the one you are standing next to.

Peter van den Engel

Spot on.

Loren Petrich

Virus-bacteria coevolution solves diversity paradox by ‘Killing the Winner’ | Carl R. Woese Institute for Genomic Biology /biotech/article/virus-bacteria-coevolution-solves-diversity-paradox-killing-winner — I’ve mostly seen that term in the context of microbial ecology, but similar effects are recognized for macroscopic organisms, though under other names. Like the the Janzen–Connell hypothesis for tropical and temperate forests, and balancing selection for immune-system antigens and receptors.

Loren Petrich

As to why tropical forests have a greater parasite and predator load than boreal ones, I think that that is related to their biomass productivity. They produce more biomass, thus being able to support more parasites and predators. Their climate is also much better for such organisms to spread.

The productivity, metabolism and carbon cycle of tropical forest vegetation – Malhi – 2012 – Journal of Ecology – Wiley Online Library https://besjournals.onlinelibrary.wiley.com/doi/full/10.1111/j.1365-2745.2011.01916.x

Tropical forests typically have around 2500 – 3500 g/m^2, while temperate forests have 1000 – 1500 g/m^2, and boreal ones around 500 – 1000 g/m^2. Tundra has very low productivity, 500 or less g/m^2, and low productivity at lower latitudes is due to aridity.

steven t johnson

I’m not altogether certain that this study will be interpreted only as evidence of significant multi-level selection in nature. It may be presented as a study in sexual selection. The most common understanding in the popularizations now is that sexual selection is adaptive because it is all about fitness markers. It is merely a special case of natural selection. (I think examples like the Irish elk are not discussed in this presentation.)

But I’ve always been under the impression that the old understanding of sexual selection is that it presented an explanation for how natural selection would fail to reach a perfect adaptation for the species. As in sexual selection for the antlers would not be adaptive for the species. My memory is that this is Darwin’s original notion of group selection , but my copy of Darwin is hidden in a box in the attic, so, maybe not? But to my eyes, this study is a counter-example to the thesis that natural selection is all-powerful. All the popularizers say there’s genetic drift and so on, but from what I’ve seen, almost all of them promptly forget anything but natural selection. And they treat the adaptive value of all traits as a given to be discovered, rather than a question to answer.

So, again, it seems to me you could read this study as an example confirming sexual selection as a mechanism that results in the propagation of deleterious traits in the species. Which by the way is one way to see gene selection too, as near as I can tell.

As to group/multi-level slection? Unlike the usual view of sexual selection and gene selection as specific modes of natural selection, it seems like both are mechanisms that decrease adaptive perfection (insofar as such a thing is even definable, a point the adaptationists tend to ignore in popularizations.) But it is group selection instead that is a mode of natural selection.

KD

I think part of the issue with group selection is that it appears that the major religions of the world can be seen as group selection strategies:

https://blogs.scientificamerican.com/bering-in-mind/gods-little-rabbits-religious-people-out-reproduce-secular-ones-by-a-landslide/

Belonging to a major religion of the world coincides with high fertility (which is probably how they became “major”). Thus, religious participation results in differential fertility rates, lowering the predominance of the “infidels” genes in each generation.

Also, religious wars make sense, as you are witnessing a competition between two gene pools for territory and resources, especially if they are both high fertility. Without looking at group selection and fertility, human investment in religion would appear completely irrational.

Ross Hartshorn

I do believe that fear of “legitimizing” religion is a very big part of why many prominent atheist scientists reject the idea of multilevel selection. You can’t talk about selection at the group level very long before the subject of religion comes up. You might think that a very pro-science group would not reject an idea because of a dislike of its consequences, but rather judge it only on its scientific merits, but they are still humans as well as scientists.

Peter van den Engel

Yes, religion is an interesting subject. You might believe religious communities having more offspring is a result of religious believe/ but it is not.
Religion has always been a means to mitigate poor economic circumstances: desease, poverty, death – and to increase offspring has exactly the same purpose/ but is not a religion.
So this is a wonderfull subject to explain multi level group selection, to proove the thinking confuses two different aspects into the same definition. Inverts it into: people having large families is a result of their religion/ while having that religion and large families were both the effect of the same reason: poor and uncertain economic circumstances.

It is not by chance that poorer cultures like Africa and South America both have a relative high religious concsiousness and large offspring. Which to some extend also applies to Mid Asia. Western cultures are fearing as a fifth muslim column infiltrating their cultures, purely by using their larger offspring and immigrate into it. I will get back to that later.

The next question is how to solve the problem of low cultures; low intelligence/ having large offspring, so it inflates, keeps repeating the same problem on a larger scale.
The origin of the problem lies in parents agricultural group thinking: having more children will create a more secure future/ while the result is inverted: because the land will never produce more than it will, no matter how many people are working it.
So it results in suspicion: tribal warfare and the central mind programming there will never be enough, so creating a fertile economy is rejected: forgotten. Therefore backward economies often are aggressive, religious and have on average a large offsprings.
Getting back to mid Asian cultures which often are rich thanks to oil/ but still maintain religion and often terrorist groups, is because their disassociated economy is controled by small family groups/ so it creates the same kind of poor economy, uncertainty for the rest, maintaining their religious potentially aggressive stance, beause of their mono economy. They created it themselves. Their wealth is deceiving. Something similar to the giant antlers of an extinct species.

So the large offspring keeps these economies poor, because they are programming their thinking into permanent shortages they have to deal with by creating a large offspring. It’s a virtual circle.
However western economies contribute to that no less by using patents to isolate their economies, from the same fear of shortages/ by creating them. It is exactly the same type of multi level group thinking by inverted reasoning.
The underlying couse for that one; peeling the union; is the financial system itself which maintains an artificial shortage consciousness, because without labor there is no income/ while the same labor overproduces more it can eat itself, so creates its own extinct in group selection.
Forgetting about patents and democratising oligarchies, will decrease the offspring and religious fear in these poor regions.

KD

Peter van den Engel:

I take your points very seriously, but the points about religion and fertility hold across the board, whether you look at Denmark or Nigeria or Singapore. Clearly, given religious endogamy, drawing a line between “belief” and a given gene pool is difficult, creating problems of whether genetics or culture is driving religion. However, I would suspect religion is primarily cultural given that major changes in religious participation and composition of populations can happen in a generation or two, which is too short for significant genetic changes.

Anyhow, I think multilevel selection will provide insight into why humans are religious, and what social functions religion plays in social orders. . . and it will turn out to promote evolutionary fitness for the group (mostly), because otherwise it would be a hell of a waste of time and resources.

Peter van den Engel

KD

Resources are always for practical use and therefore never a waste.
The concept energy resources are scarce is a delusion. Free (photon) energy from the sun does not influence its mass, thanks to quantum physics.
However the break (wave) in the circle; which is also the cause of life; like day and night, summer and winter and individual death; creating a relative shortage and potential misallocation of energy, is the reason for people being religious. To still believe in eternal life. Actually it is not a scientific mistake.

You are right asking questions, this is what scientists do all the time.

J. Daniel

Peacock feathers and huge antlers weigh down their bearers. But what about humans? We have no feathers or antlers. But maybe we do have traits that weigh us down for sexual selection reasons. One candidate is female breasts, which have significant weight, presumably for appearance and unrelated to milk production. In other species, this is not the case. Another candidate is male shoulder width. I recall the hypothesis that this is selected for as a sexual characteristic and not for other reasons. So the same considerations apply in this case as well.

Loren Petrich

We have several features that may plausibly be interpreted as ornamental or otherwise sexually selected. Ornamental, like deer antlers or lion manes or many male birds’ colorful feathers.

Men: big chests, facial hair, baldness, low voices.
Women: breasts.

There is something weird about our species. The “Beauty Myth” Is No Myth : Emphasis on Male-Female Attractiveness in World Folktales. – PubMed – NCBI https://www.ncbi.nlm.nih.gov/pubmed/26181463 — greater interest in female beauty than male beauty, something that seems to be cross-cultural. I concede that there is plenty of cross-cultural evidence of male vanity, like the numerous facial-hair fashions, so the difference is likely relative. This emphasis on female beauty is contrary to what one finds in much of the animal kingdom — the more ornamented sex is almost always the male sex.

Peter van den Engel

In response to Wladimir Dinets.

Of course Wikipedia is also just human and depends on opinions of a small group of sometimes bias academics.
Also your explanation of wikipedia proves this (selective perception) since the article mentions human hunting extincting animals occurred on isolated islands only and next to that the prime cause was climate change. As current global warming is the potential cause for animal species going extinct. So this is not because of human hunting. Also the extinction of the dinosaur was due to climate change, of which about five or six huge ones happened in earths history. I don’t suppose a meteorite was the single cause for that. The changing admosphere and in relation temperature where due to that.
What’s completely missing in the article is sexuality, heredity and climate in relation to micro organisms resulting in loss of biological resistance, something like aids is killing people/ although looking at sub sahara cultures the birth rate can compensate for that, as a human behavioral resistance mechanism, so it is hard to pinpoint one reason for total extinction. It might also be that a species becomes less favorite, so it withdraws/ next to a more popular group using all available food, or its own hunting posibilities. In combination to that climate change; like disappearing forests; could have led to the extinction of the species.

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