“genes for altruism”

in Genes underlying altruism published in october of last year, three biologists/researchers think through what “genes for altruism” ought to look like and how we will recognize them (“we” meaning teh scientists!):

(i) Genes underlying altruism should satisfy Hamilton’s rule of rb > c, where r is relatedness of actor to recipient, b is benefits to the recipient and c is costs to the actor. Altruism exists, and to the extent that this type of behaviour has evolved, we expect genetic variation to underlie it. In this sense, there must be genes ‘for’ altruism (genes showing allelic variation that is statistically associated with variation in altruistic behaviour) that are potentially detectable….

(ii) Genes underlying altruism should be environmentally sensitive. If genes for altruism are to evolve, then at least some carriers must reproduce. This inference implies that genes underlying altruism should be conditionally expressed as a function of their social environment….

(iii) Genes underlying altruism should increase in number and complexity with social-behavioural sophistication….

(iv) Genes underlying altruism should coevolve with, or depend on, the previous evolution of genes for kin recognition….

(v) Genes for altruism may reside in regions of low recombination, exhibit co-expression and show modular genetic architecture….

(vi) Genes underlying altruism should be at least partially additive. The evolution of altruism requires heritable variation, and we therefore expect genes for this and other evolved social traits to have significant additive effects that are responsive to kin-mediated selection….

(vii) Genes underlying altruism should exhibit strong pleiotropy. Pleiotropy (multiple phenotypic effects of alleles) should be fundamental to the evolution of altruism, given that it involves combinations of costs and benefits that may be simultaneously physiological, morphological, reproductive and behavioural….

the authors offer some candidate “genes for altruism” (this is a truncated version of their table. i’ve only included the ones for humans here — they also suggested some for eusocial insects):

i think teh scientists should also look for some genes related to violence — particularly tempermental, hotheaded sorts of violence — the kind that raises the testosterone levels of scots-irish, but not yankee, folks when they’re insulted. those types of fly off the handle behaviors, i think, are often altruistic in nature, since the hotheaded individual can be more willing to sacrifice himself in a fight or in battle for his kin.

also, i guess that “genes for altruism” ought to be found in differing frequencies — even variations — in different human populations, especially long-term inbred versus long-term outbred ones.

(^_^)

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inbreeding and outbreeding

i keep saying that i’ll define more clearly what i mean by “inbreeding” and “outbreeding,” but i never do. finally! — here i am, and i’m gonna do it! (^_^)

from the oxford dictionary of biology:

– inbreeding: “Mating between closely related individuals, the extreme condition being self-fertilization, which occurs in many plants and some primitive animals.” (see also wikipedia.)

– outbreeding: “Mating between unrelated or distantly related individuals of a species.”

great. but what’s “closely related” or “unrelated” or “distantly related”? self-fertilization doesn’t really apply to humans (at least not very often — i hope), so where to draw the line between “closely related” and “distantly related”?

i’m primarily interested in the evolution of altruism and other “innate social aptitudes” in man [pdf] — and here’s where inclusive fitness comes into the picture, btw — and the role that inbreeding and outbreeding might play in all that.

inbreeding in and of itself does not change the frequencies of genes in a population — it just moves them around, concentrating them in certain lineages. however, wade and breden showed in some mathematical wizardry modelling that, under certain circumstances, long-term, sustained inbreeding can, in fact, lead to increased frequencies of “genes for altruism” in a population.

wade and breden looked at four inbreeding scenarios: 1) self-fertilization (doesn’t happen in humans); 2) if the mating individuals shared half (50%) their genomes in common (like parent-offspring matings or sibling matings); 3) if the mating individuals shared 20% of their genes in common (this is somewhere in between first cousins and double-first cousins or uncle-niece/aunt-nephew); and 4) if the mating individuals shared no genes in common (not the typical pattern in human matings). most human populations do not practice parent-offspring/sibling matings — in fact, it’s usually avoided and considered by most as really icky. but quite a lot of peoples regularly marry first cousins, and some (in the arab world/middle east) even often marry double-first cousins — nor is the world short on uncle-niece pairings (southern india, for example — or hasidic jews).

wade and breden found that, under certain circumstances, long-term, sustained matings between individuals that share 20% of their genomes in common can lead in an increase in altruism genes in that population. first cousin marriage, probably the most common form of inbreeding in humans, is a little short of what wade and breden looked at, but it’s not terribly far away either (12.5% relatedness vs. 20% relatedness). you would think that the slope of the line for inbreeding at 12.5% relatedness would fall somewhere in between that for 0% and 20% (solid black line) on wade and breden’s lower graph here:

in clinical genetics, most researchers look at degrees of inbreeding that are between second cousins or closer, commonly referred to in the literature as consanguineous marriages. since i get a lot of my data on inbreeding from such studies, it’s kinda handy for me to define inbreeding as anything between second cousins or closer, but in reconsidering wade and breden’s results, i’m thinking that maybe i should only concentrate on first cousins or closer. for now i think i’ll stick to second cousins or closer, but i reserve the right to change my mind (it is a woman’s prerogative, isn’t it? still?).

so, on this blog:

– inbreeding = in a population, a general pattern of regular and sustained mating between individuals who are related to one another as second cousins or closer.

– outbreeding = in a population, a general pattern of regular and sustained mating in which individuals avoid second cousins or closer.

notice the “regular and sustained” bit. that’s important. we’re not talking here about occasional marriages between cousins. it has to be a regular practice in a society. i’m not sure what the frequency of the inbreeding needs to be. it will vary according to population size, of course — the smaller the population, the more closely related everyone’s going to be anyway (e.g. the yanomamo). in a larger population? — dunno. definitely when 50% of marriages are consanguineous over the long-term i think the frequencies of “genes for altruism” are going to increase pretty rapidly (i’ll come back to what sorts of altruism in another post). 30%? probably. 3%? not really.

outbreeding, too, needs to be “regular and sustained” to have any effect, i.e. to have a population slide back down wade and breden’s slope in reverse. one generation of outbreeding probably won’t have much of an effect, i think. evolution (natural selection) does take some time, after all. also, if one inbreeding group interbreeds with another inbreeding group, that’s NOT outbreeding according to my definiton. technically it is in biological circles, but if we’re talking about two populations that have been inbreeding for a long time and, therefore, have acquired a lot of genes for my “familial altruism,” then all they’re doing by interbreeding is swapping familial altruism genes. for example, if you’re the early medieval irish and are clannish because you’ve been inbreeding for who-knows-how-long, the “outbreeding” that you do with the vikings when they show up (probably) doesn’t count wrt altruism, because they’re a long-term inbreeding group, too.

to have any effect on the frequency of certain “genes for altruism,” outbreeding — like inbreeding — needs, i think, to be regular and sustained over the long-term, as it was with europeans (mostly northwest europeans) since the early medieval period (see also mating patterns in europe series in left-hand column below ↓ for more details) and, perhaps, some other groups like the semai in malaysia.

previously: inbreeding and the evolution of altruistic behavior

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looking for altruism genes

so, the tidbit of info in the previous post about the mccoy clan being predisposed to von hippel–lindau disease (75% of the mccoy clan have had tumors on their adrenal glands — says so in wikipedia so it must be true), got me to thinking about what sorts of congenital conditions might offer clues to “genes for altruism” a la cochran, hardy & harpending [pdf].

re. the mccoys and von hippel–lindau disease:

“Some descendants of the McCoy family (involved in the Hatfield-McCoy feud of Appalachia, USA) as well as the Elliotts have VHL. In an article appearing in the Associated Press, it has been speculated by a Vanderbilt University endocrinologist that the hostility underlying the Hatfield–McCoy feud may have been partly due to the consequences of von Hippel–Lindau disease. The article suggests that the McCoy family was predisposed to bad tempers because many of them had a pheochromocytoma, which produced excess adrenaline and a tendency toward explosive tempers.“

hmmm. excess adrenaline. that could certainly be beneficial if the sort of altruistic behavior you need to have to be reproductively successful is the kind where you’re willing to go out and fight the competing clan on behalf of your own.

so i started thinking about everybody’s favorite aggressively tribal inbreeders — the arabs — and aaaall the congenital disorders they have and if any of them might be related to adrenalin and/or the adrenal glands.

here’s one — congenital adrenal hyperplasia:

“Congenital adrenal hyperplasia (CAH) refers to any of several autosomal recessive diseases resulting from mutations of genes for enzymes mediating the biochemical steps of production of cortisol from cholesterol by the adrenal glands (steroidogenesis)…. CAH is a genetic disorder in which girls are masculinized because the adrenal glands secrete large amounts of androgen during prenatal development. The extra androgen does not affect a baby boy’s physical development, but in baby girls it can enlarge the clitoris so that it resembles a penis….

“Most of these conditions involve excessive or deficient production of sex steroids and can alter development of primary or secondary sex characteristics in some affected infants, children, or adults.”

so here’s a genetically recessive condition — so, like sickle cell anemia, you need to have two copies of the “bad” allele to have the condition — that masculinizes girls ’cause the female fetus is exposed to lots of androgen. and male fetuses are not affected? at all? couldn’t they be “extra” masculinized in some way? maybe that’s not the case, but it sure makes me wonder.

and androgen certainly has interesting effects on the brain:

“Circulating levels of androgens can influence human behavior because some neurons are sensitive to steroid hormones. Androgen levels have been implicated in the regulation of human aggression and libido.”

well, what do you need to survive in a warring clannish/tribal society but high levels of aggression? amirite?!

the world-wide incidence of CAH is 1:14,199 live births. in kuwait it’s 1:7,000 and amongst moroccan jews it’s between 1:5000-1:7000 (i know, i know — they’re not arabs — but they’re part of the same sort of clannish, inbreeding society being in morocco). there are also apparently high rates in egypt (alexandria), but i don’t know what the prevlance is. it’s also considered a problem in tunisia, jordan, oman, uae and saudi arabia.

here’s a breakdown of the prevalence in several populations:

1:282 – yupik eskimos of southwestern alaska
1:2,141 – edit: la reunion, france (or la reunion, france? see comments.)
1:5000-1:7000 – moroccan jews
1:7,000 – kuwait
1:10,866 – france (whites)
1:10,866 – italy (whites)
1:14,500 – new zealand
1:15,800 – japan
1:17,098 – scotland

carriers of one allele related to CAH often exhibit “symptoms of androgen excess.”

androgen excess? aggression? high prevalence in the arab world? clannish/tribal societies? possible “genes for altruism”?

dunno. just a thought.

previously: hatfields and mccoys and which altruism genes?

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inbreeding and the evolution of altruistic behavior ii

in Understanding Human History, michael hart did a real nice job of explaining how kin selection or inclusive fitness works and how “genes for altruism” could be selected for [pgs. 37-38]:

“For about a century after Darwin proposed his theory of evolution, the origin of altruistic behavior in animals remained a puzzle. It was not until the 1960s, when William D. Hamilton proposed his theory of kin selection, that a satisfactory explanation was given. That theory can perhaps best be explained by an example:

“Suppose a man sees his identical twin drowning in a river, and estimates (correctly) that if he were to jump in and try to save his brother the probability of success would be 80%, while the probability that he would die in the attempt would be 20%. Consider these two alternatives:

“a) Some of the man’s genes strongly dispose him to rescue his brother, and he therefore jumps in and tries to save him (‘altruistic behavior’).

“b) The man does not have genes that dispose him to rescue his brother, and he therefore stays on the shore and lets his brother drown (‘selfish behavior’).

“In case (b), exactly one copy of the man’s genes survives, and may later be replicated. However, in case (a), if the rescue attempt is successful, two copies of the man’s genes survive (one in his own body, one in his brother’s). As this will happen 80% of the time, on average 1.6 (= 0.80 × 2) copies of the man’s genes will survive. In this situation, therefore, genes that dispose a person to altruistic behavior will — on average — have more surviving copies than genes that dispose a person to act selfishly and will be favored by natural selection.

“Now consider a slightly different example. Suppose that the man on shore is a brother — but not a twin — of the person who is drowning. Case (b) will still result in one copy of his genes being preserved. However, since ordinary siblings share only 50% of their genes, if the man on shore succeeds in rescuing his brother then (on average) 1.5 copies of the man’s genes will survive. Since 80% of the attempts will be successful, case (a) will on average result in 1.2 (= 0.80 × 1.5) copies of the altruistic genes surviving. Since 1.2 is greater than 1.0, the altruistic genes will be favored by natural selection in this case too.

“Suppose, however, that the two men were not brothers, but merely first cousins. First cousins, on average, share only one-eighth of their genes. In this case, altruistic behavior results in only 0.9 (= 0.80 × 1.125) copies of the man’s genes surviving, and natural selection will therefore favor the genes for selfish behavior.

“The upshot is that a gene that disposes its bearer to behave altruistically toward a close relative can have a selective advantage over one that disposes its bearer to act completely selfishly. Furthermore, this can occur even though the relative never returns the favor, and even if the survival of the relative does not increase the group’s chances of survival. It is not necessary that either reciprocal altruism or group selection operate for kin selection to result in the spread of genes that dispose their bearer to act altruistically toward close relatives.”
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what’s missing from these examples is, of course, inbreeding. and depth of time.

take michael’s second example up there…

“Suppose that the man on shore is a brother — but not a twin — of the person who is drowning.”

…but let’s add that the parents of these brothers were first-cousins. that makes these two guys: brothers AND second-cousins (i.e. the children of two first-cousins). so they probably share not only 50% of their genes in common as brothers, but also 3.13% of their genes in common as second-cousins. so the “push” to jump in the water to save the brother/cousin must be somewhat stronger in the inbred pair than for the brother to save just a plain ol’ brother.

now let’s take this example of michael’s…

“Suppose, however, that the two men were not brothers, but merely first cousins. First cousins, on average, share only one-eighth of their genes.”

…but let’s make them double first-cousins rather than just first-cousins. what happens then?

well, while first-cousins probably share 1/8th or 12.5% of their genes in common, double first-cousins share … well, double that! … or 1/4 or 25% of their genes in common.

what happens to michael’s calculation then?

“In this case, altruistic behavior results in only 0.9 (= 0.80 × 1.125) copies of the man’s genes surviving, and natural selection will therefore favor the genes for selfish behavior.”

in the case of double first-cousins the calculation becomes 0.80 x 1.25 = 1.0. that’s just breaking even using michael’s example, but what if the odds of saving the cousin from drowing are better than 80%?

or what about the depth of time i mentioned above? what if the family of my double first-cousins has been inbreeding for a very long time. a very, very long time. like for fifty generations or more. then the relatedness between all the family members, including these double first-cousins, will be even closer. natural selection ought, then, to favor such double first-cousins jumping in to save each other.

as wade and breden showed (see also previous post), inbreeding can help to accelerate the rate of the evolution (or frequency in a population) of altruism genes [pg. 846]:

[T]he increase in matings between homozygous parents decreases the genetic variance within families, because these matings produce genotypically homogeneous arrays of offspring.”

repeated inbreeding in a family reduces the diversity (whoa!) of the allele types within that family, and if we’re talking about “genes for altruism” here, then the variety of those must get reduced within inbred families, too. in a population that consists of, say, ten inbreeding families, the one that has super-duper altruism genes that lead all of its family members to help each other out more than the members of the other families will have the advantage (provided selection favors that advantage for whatever reasons). and those super-duper altruism genes will no doubt eventually spread to the other families since, in reality, no family groups inbreed 100% of the time anywhere — there will pretty definitely be gene flow between families. so then you’ll get a whole population of super-duper family altruists (note that these people are NOT altruistic to unrelated individuals).

the human populations on earth today that inbreed most closely (within patrilineages) and often practice double first-cousin marriage — AND have been doing this for prolly at least a couple of thousand years (time depth) — are the arabs (who later spread these mating practices to the maghreb, the mashriq and far off places like iraq and afghanistan and all the other ‘stans) and some peoples in the levant like the druze. i think that, because of their long-standing mating practices, they are the prime human examples of wade and breden’s accelerated evolution of altruism thanks to inbreeding.

previously: inbreeding and the evolution of altruistic behavior and more on inbreeding and the evolution of altruistic behavior

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more on inbreeding and the evolution of altruistic behavior

remember this?:

those are a couple of graphs from wade and breden from when they did some mathematical modelling of the selection for “genes for altruism” under different circumstances (see previous post for more details).

the interesting graph is the bottom one which shows what the frequency of “genes for altruism” in a population would be IF selection was strong and IF the alleles in question were dominant. the gene frequencies are on the y-axis (at 1.0 the genes have reached fixation). the number of generations to get to the various gene frequencies is on the x-axis.

the interesting line on the graph for us is the solid line: those are individuals who are about two-times more related to one another than first-cousins in a randomnly mating population. that’s an exaggeration for most human populations, but it’s the most human-like of all the mating patterns they considered. the others are cloning, sib-mating (ewww!), and total outbreeding. so most human populations would be lower than that solid line, but not flatlining like the total outbreeding example. somewhere in between.

anyway. in my previous post i pointed out that after just 50 generations, there is already an increase in the frequency of “genes for altruism” in the solid line population. however, these models start at zero! in other words, the starting point they’re thinking of is if the populations start off with no “genes for altruism” at all. but that can hardly have ever been the case for any human population since altruistic behaviors are found in almost every living being on the planet!: plants, insects … even slime molds! not to mention our closest cousins, other primates.

so the baseline for the frequency of “genes for altruism” in any human population was probably never zero. who knows where it should be? 30%? 40%? 50%? 80%? i really don’t know. but not zero, anyway.

if we just say it was 50% — just picking an example right out of the hat — then the frequency of “genes for altruism” in the inbreeding solid line population increases much more sharply (i.e. the slope of the line is more slopey) over fifty generations than if we start the population off at zero. (look at the solid line between 0 and 50 generations versus 200 and 250 generations. there’s a much sharper increase in the latter group.)

i’m picking out 50 generation timespans, btw, because — at a very conservative estimate (1 generation=25 years) — arabs have been very closely inbreeding for ca. 56 generations (i.e. since at least mohammed’s days and most likely before).

anyway. that is all. (^_^)

previously: inbreeding and the evolution of altruistic behavior

update 05/30: see also inbreeding and the evolution of altruistic behavior ii

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two things

1) inclusive fitness — hamilton’s idea that your genetic success should be calculated by considering both your direct descendants AND other individuals who happen to share copies of your genes and whom you have aided in some way — means that individuals who are more altruistic towards those other individuals with whom they share a good deal of genes, close-ish family members being the most likely candidates, increase their total fitness. inbreeding, because it amplifies the relatedness between family members, can amplify the altruistic behaviors between them.

2) altruistic behaviors are behavioral traits that are selected for under certain conditions (selective pressures) because such behaviors pay off (i.e. increasing an individual’s fitness or inclusive fitness). there are many, many, many types of altruistic behaviors, including those that are on the “dark side” of altruism (bigotry, waaaaycism, genocide), so there cannot possibly be just one “gene for altruism.” inbreeding, because it amplifies the relatedness between family members, can make the evolution of “genes for familial altruism” easier/happen more quickly (see here and here).

(ok. so technically that’s more than just two things. so sue me! (^_^) )
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regarding the first point — inbreeding, because it amplifies the relatedness between family members, can amplify the altruistic behaviors between them — let’s take two examples: a population that breeds entirely randomly (doesn’t really exist in humans) and a population that inbreeds (cousins marry cousins regularly, for instance).

in the randomly breeding (diploid) population, the relatedness between the various family members looks like this. in such a population, first-cousins will probably share 1/8th (12.5%) of their dna in common; that’s an inbreeding coefficient of 6.25%.

first-cousins in the regularly inbreeding population will share a greater amount of dna in common because they share so many ancestors in common, so their inbreeding coefficients will be higher. for instance, some first-cousins from pakistan and saudi arabia, two societies with very long histories of cousin marriage, have inbreeding coefficients of 11%, almost double those in a randomly mating population.

so, all else being equal (which is obviously never the case), if we take a totally made-up example of an altruistic behavior — the sharing of bananas — one would expect to find that the first-cousins in the inbreeding population, since they are more closely related to one another, share more bananas with each other on average than the first-cousins in the randomly mating population. the first-cousins in the randomly mating population should share more bananas with each other than they do with their second-cousins, because they share more genes with each other than they do with their second-cousins — but overall their altruistic behaviors won’t hold a candle to the inbred first-cousins.

got that? (^_^)

macaque monkeys provide a good example of how more closely related family members are more altruistic towards one another than more distantly related family members. the closer the genetic relationship, the more grooming between two macaque relatives; the more distant the relationship, the less grooming

confused beetles provide a good example of how more inbred family members are more altruistic towards their close relatives than randomly mated family members are. in this case, we’re talking about an example of the “dark side” of altruism: randomly mated confused beetles cannibalize other related confused beetle larvae more than inbred ones.

steve sailer applied these ideas to humans way back in 2003. from Cousin Marriage Conundrum:

“Are Muslims, especially Arabs, so much more loyal to their families than to their nations because, due to countless generations of cousin marriages, they are so much more genealogically related to their families than Westerners are related to theirs? Frank Salter, a political scientist at the Max Planck Institute in Germany whose new book ‘Risky Transactions: Trust, Kinship, and Ethnicity’ takes a sociobiological look at the reason why Mafia families are indeed families, told me, ‘That’s my hunch; at least it’s bound to be a factor.’

“One of the basic laws of modern evolutionary science, quantified by the great Oxford biologist William D. Hamilton in 1964 under the name ‘kin selection,’ is that the more close the genetic relationship between two people, the more likely they are to feel loyalty and altruism toward each other. Natural selection has molded us not just to try to propagate our own genes, but to help our relatives, who possess copies of some of our specific genes, to propagate their own.

“Nepotism is thus biologically inspired. Hamilton explained that the level of nepotistic feeling generally depends upon degree of genetic similarity. You share half your personally variable genes with your children and siblings, but one quarter with your nephews/nieces and grandchildren, so your nepotistic urges will tend to be somewhat less toward them. You share one eighth of your genes with your first cousins, and one thirty-second with your second cousin, so your feelings of family loyalty tend to fall off quickly.

“But not as quickly if you and your relatives are inbred. Then, you’ll be genealogically and related to your kin via multiple pathways. You will all be genetically more similar, so your normal family feelings will be multiplied. For example, your son-in-law might be also be the nephew you’ve cherished since his childhood, so you can lavish all the nepotistic altruism on him that in an outbred family would be split between your son-in-law and your nephew.

“Unfortunately, nepotism is usually a zero sum game, so the flip side of being materially nicer toward your relatives would be that you’d have less resources left with which to be civil, or even just fair, toward non-kin. So, nepotistic corruption is rampant in countries such as Iraq, where Saddam has appointed members of his extended family from his hometown of Tikrit to many key positions in the national government….”
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what i got interested in was the flip-side of what steve talked about. in other words, if inbreeding leads to the sort of nepotistic behaviors we see in the middle east, maybe not-so-much inbreeding — or even outbreeding — leads to the opposite. lots of inbreeding in humans seems to lead to all sorts of family-oriented, clannish behaviors, not just nepotism. it even seems to, as randall parker pointed out, impede the development of democracy because everyone’s so focused on their extended families/clans/tribes. again, maybe outbreeding does just the opposite. i think there’s a lot of pretty good evidence pointing in these directions (see the Mating Patterns series down below ↓ in the left-hand column), but so far it’s all circumstantial.

furthermore, point number two from the top: inbreeding, because it amplifies the relatedness between family members, can make the evolution of “genes for familial altruism” easier/happen more quickly. not only are inbred populations of humans more likely to be more altruistic to their near kin than not-so-inbred populations because they are more closely related to one another (like the confused beetles), various “altruistic alleles” related to familial altruism ought to develop more quickly and be more frequent in the inbred populations (again, see here and here).

greg cochran’s not convinced. he said: “Your general notion that the degree of inbreeding does something, by itself, in the short run, is incorrect.”

i think he’s misunderstood my argument (well, how much can one communicate in a couple of comments to a blog post?). i am not arguing that “inbreeding does something by itself“ — except for potentially amplifying already existing altruistic behaviors (see the beetle example again). nor am i arguing that “inbreeding does something, by itself, in the short run.” no. of course, any “genes for altruism” would have to be selected for (or not) over some amount of generations.

wade and breden found that inbreeding accelerates the spread of altruism genes in a population, and that “genes for altruism” would already be on the increase after just fifty generations if the selection was strong and the genes dominant. populations like arabs in the middle east have certainly been inbreeding closely for well over fifty generations (i’ve over-estimated the length of generations at 25 years/generation to come up with a conservative guess of how long they’ve been inbreeding). and northwest europeans have been doing just the opposite for something like fifty generations or so. the one group is almost freakishly oriented towards the extended-family/clan/tribe; the other, as m.g. miles put it, to the commonweal.

i think there’s been an almost exactly opposite evolutionary history in terms of altruism in these two populations over the last one thousand years (how cool is that?!) — an evolution that’s ongoing, of course, since middle easterners are still inbreeding and northwest europeans are outbreeding more and more.
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greg also said:

“Imagine that in much of history, people lived in small groups that often fought with their neighbors. In that sort of situation, selection for group altruism is at least possible, since the group is full of close relatives, while the opponents are less closely related. Both sides are probably members of the same broad ethnic group or race, but that doesn’t matter: only the kinship coefficients matter.

“Suppose that many people emerge on to the stage of history with this impulse to fight for their side: in the past, this always meant closely related people. Now, with the emergence of states, they find themselves fighting in armies, which feel like their side, but are no longer closely related – not a bunch of cousins and such. It could well be that many individuals are actually willing to risk themselves for that state. They’re willing to die for truth, justice and the Assyrian Way. It’s not genetically smart, but their adaptations are wired for past circumstances….

“Over time, this misfiring of altruism should decrease. Patriotism burns itself out. Dying for Assyria doesn’t do your close relatives any good at all. Some people will be more prone to this, some less, and that tendency will be heritable. Those with a tendency to volunteer (in the service of anything other than close relatives) should dwindle away over time.“

yes. familial altruism (all sorts of behaviors!) can be misapplied in new circumstances. but i think that what greg describes would only occur IF you started off with a population with lots of smaller, somewhat related but inbred sub-groups which had lots of “genes for familial altruism” and then brought them together into a state. maybe like the roman empire. or any of the chinese empires.

BUT there are other sorts of altruism beyond familial altruism — like reciprocal altruism — tit-for-tat sorts of behaviors, for example.

if you started off, not with a population that consisted of sub-groups with lots of “genes for familial altruism,” but rather a population with more “genes for reciprocal altruism,” the patriotism may not be quite so artificial. i suspect — but have no real proof, of course — that northwest europeans are such a population.

to quote myself from over @west hunter [links added]:

“i wondered before, though, if an opposite of these sorts of kin-oriented altruism alleles might be certain types of reciprocal altruism alleles. you know: the ones behind tit-for-tat sort-of behaviors, etc.

“if you have a population that oubreeds A LOT (nw europeans from the middle ages onward) in which family and kin connections are downplayed (prolly because of the outbreeding) — AND you have the ‘right’ sort of selection pressures (something that selects for cooperation and corporate behavior, like medieval manorialism and farming in a cold climate) — then maybe the frequencies for whatever alleles code for reciprocal altruism increase because lots of reciprocal altruism increases your success at reproducing.”

if you kept warring, you would still burn through the most patriotic members of the group (think wwi and wwii), but you wouldn’t be left with clans at the end of the day (see the rest of greg’s comment below). perhaps bunches of self-oriented nuclear families/individuals, but not clans.

speaking of misapplied altruism, i think our reciprocal altruism is now being misapplied in the face of migrating mexicans and muslims and all sorts of third world populations who, on the whole, are not big into reciprocation.
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finally, greg said:

“But states are older in some places than others, and some have made greater demands than others. Imagine a region where states have been around longer, a place in which the locals have lived through empire after empire after empire. They should have had the patriotism bred clean out of them. They should feel altruistic about their families, maybe their clan – and nothing else.“

yes, they do — middle easterners (the strongest of the inbreeders) and to a lesser extent the chinese (who also have a very long history of inbreeding) feel more altruistic about their families and their clans, but that’s not because they had the altruism/patriotism bred out of them. they’re sooo inbred (the muslims way more than the chinese) that they never had any patriotism in the first place! they have such strong drives for familial altruism that anything like patriotism doesn’t even enter into the picture. feelings of patriotism — nationalism — have historically been strongest amongst northwest europeans — the most outbred, civic, and “corporate” peoples in the world.

i think there are some really cool evolutionary histories that led to these differences in altruistic behaviors — differences which are some of the most profound, innate differences between human populations that are out there — the instinctive feelings guiding us in how to treat the others around us.
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see also: Giving Bigotry a Chance and Your country’s not your blood from henry harpending and greg cochran @west hunter (who seem to have caught the inbreeding/outbreeding & altruism bug! (~_^) ).

previously: inbreeding and the evolution of altruistic behavior and four things and which altruism genes? and inclusive inclusive fitness

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inbreeding and the evolution of altruistic behavior

michael wade (the beetle guy) and felix breden worked up some mathematical models of the possible frequencies of “genes for altruism” in several different types of inbreeding populations.

they took different degrees of inbreeding/outbreeding …

– mating with oneself or a clone (100% related)
– mating with a sibling (50% related)
– mating with a more distant relative (20% related, i.e. not quite half-siblings)
– no inbreeding at all (0% related)

… and via wizardry (i.e. advanced algebra) they worked out how “genes for altruism” would fare in each of these populations over the course of many generations. in other words, would altruism genes become more frequent or not in these various populations?

they factored in different parameters such as whether the gene(s) (alleles) in question were dominant or recessive, and whether the selection pressures on the alleles were weak or strong. weak selection apparently refers to those cases in which one “phenotype is slightly advantageous over another.” presumably strong selection means the opposite.

here’s what wade and breden found:

under weak selection — instances in which the altruism alleles only confer slight advantages to those who have them (top two graphs) — the altruism alleles really only increase in any significant way when the individuals self-mate (or mate with clones) or mate with their full-siblings. there’s some increase in altruism alleles in populations where mating occurs between individuals who are almost half-siblings and the alleles are dominant, but that increase really doesn’t become apparent until after several hundred generations of inbreeding.

under strong selection (lower two graphs), again the altruism alleles increase in frequency the most when the individuals self-mate or mate with full-sibs. however, there is also a marked increase in populations where mating occurs between individuals who are almost half-sibs AND the alleles are dominant. in fact, the slope really takes off after just fifty generations or so (solid line, bottom graph).

the authors conclude that: “Increasing the level of inbreeding can greatly increase the rate of change of gene frequency of the altruistic allele.”

i’m interested in the evolution of altruism in humans, though, and not many humans mate with themselves (yet) or even their full-siblings. what’s more common, as we all know by now, is cousin marriage.

mating with your first-cousin in a population where inbreeding doesn’t normally occur means your relatedness to your cousin is probably around 12.5%, much lower than the lowest inbreeding rate that wade and breden looked at (20%). however, in populations where inbreeding is frequent and regular, the coefficients of relatedness are much higher — for instance, some (many?) pakistani and saudi cousins have a coefficient of relatedness of around 22% (11% coefficient of inbreeding x 2). that’s pretty much the same as the lowest degree of inbreeding that wade and breden looked at.

i think it’s apparent by looking at human behavior that inbreeding affects the frequencies of altruism alleles in different human populations, but since we don’t even know what those alleles are yet, this hasn’t been proven one hundred percent. if wade and breden did their sums right, then my guess is that (at least some) altruism alleles in humans must be dominant and must confer a good deal of advantage to those who have them. in other words, if we could graph the frequencies of altruism alleles in humans who marry their cousins regularly over time, i think they would look something like the bottom graph above, although perhaps with a trajectory that wasn’t quite so sharp (since in no population does cousin marriage happen one hundred percent of the time in every generation).

the arabs, for example, have been marrying their first-cousins (often double-first-cousins) since at least mohammed’s days, or something like 1400 years ago. if we take a very conservative generation length as twenty-five years, that’s roughly 56 generations of inbreeding up to the present. at least. plenty of time, according to wade and breden, for altruism alleles to increase in that population — provided the alleles are dominant and the selection is strong.

a couple of other things to keep in mind: 1) like genes for height or intelligence, there are probably many genes for altruism, so we have to imagine some sort of cumulative effect of many genes on human behavior, i.e. we’d have to draw many charts to map the frequencies of many genes; 2) individuals in a population might share lots of alleles for reasons other than recent inbreeding, such as a population’s ancestors having gone through a bottleneck at some point in the past. you’d think that that could also contribute to the number of shared altruism alleles in a population.

update 04/30: see also more on inbreeding and the evolution of altruistic behavior

update 05/30: see also inbreeding and the evolution of altruistic behavior ii

previously: technical stuff and which altruism genes?

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me and max

weber, that is. (^_^)

here’s a bit from alan macfarlane’s “The Origins of English Individualism” which i started reading last night [pgs. 50-51]:

“Behind Weber’s work there is a general evolutionary model that sees societies originating in a stage at which kinship dominates all life and large ‘clans’ absorb the individual, moving through an intermediate phase in which the larger grouping have been broken down by various pressures, to modern society where the family and kinship no longer dominate economic and social life. In China and India such a movement has never occurred. In China ‘the fetters of the kinship group were never shattered,’ every individual was completely submerged in the clan system, and any nascent move towards individualistic capitalism was crushed by the power of kinship groups, by the intimate link between family and land. In Europe, however, a number of factors worked together to break the original ‘clan’ system, according to Weber. One was Christianity, which encouraged an abstract, non-familistic attitude, stressed the individual believer: ‘every Christian community was basically a confessional association of individual believers, not a ritual association of kinship groups.’ This ‘all-important destruction of the extended family by the Christian communities…’ was the foundation upon which an autonomous bourgeoisie developed in the cities of western Europe. But while Christianity in general was a dissolvent of the earlier state, Protestantism was especially powerful in its attack on the earlier kinship ‘fetters.’ Weber argued that:

“‘[T]he great achievement of ethical religions, above all of the ethical and asceticist sects of Protestantism, was to shatter the fetters of the kinship group. These religions established the superior community of faith and a common ethical way of life in opposition to the community of blood, even to a large extent in opposition to the family.’

“In addition to Christianity and Protestantism, there were other pressures. The growth of towns in the middle ages also put a stress on the individual rather than the wider kinship group. Furthermore, the politcal system of feudalism was incompatible with extended kinship ties; ‘the land is divided by the feudal lord, in independence of clan and kinship…. We may simplify Weber’s ideas into the argument that there had been three stages in the evolution of modern society. First was ‘clan’ society, where kinship was paramount and the basic economic, social and religious unit was a wide group of kin; this had disappeared in north-western Europe by at least the thirteenth century, although traces remained. This was replaced by a second, intermediate, phase in which the basic unit was the household of parents and children…. This configuration was finally destroyed, Weber argues, first in England from the later fifteenth century, and later elsewhere, allowing for the third stage — the separation between family and business and the economic isolation of the individual.”

like i said before, bigger and (much!) better brains than mine have thought long and hard about the individualistic nature of northwest europeans, which stands in stark contrast to just about everybody else on our little planet, and how we got this way. but what most (all?) of them missed is the biology of it.

and that’s O.K.! ’cause they’ve been historians and philosophers and so on, and weren’t really thinking about biology (although it’s high time that they did! and a lot of them now are, which is a good thing.) and max weber was busy, you know, laying the foundations of sociology and other disciplines, so it’s ok that he missed the biology of it.

otherwise, i think he was right on target here. he really identified some of what i think were the major selection pressures on medieval european populations that resulted in their shift from clannish to individualistic societies. macfarlane criticizes weber for getting the timing wrong (i haven’t finished the book yet, but i think this is where he is going) — i.e. that english individualism happened a lot before weber’s suggestion of the fifteenth century — but otherwise i think weber was very much on target.

i think he might’ve been wrong about protestantism, though. weber seems to have been imagining that sentiments and attitudes are mutable in a blank slate kinda way — like these things just float out of the ether or something. obviously this is not the case — people have natures that are innate — and different peoples have different natures (not completely different — we are all human). and, so, to get from clannishness to individualism, you need some change in the nature of the people.

my guess is that this change has to do with, for one thing anyway, genes related to altruistic behaviors — and since altruistic behaviors are related to (heh) relatedness — then the changes in nw european behavior, i think, came from changes in mating patterns (which would’ve changed the relatedness) rather than just some abstract notions like “confessional associations.” in other words, you need to break down — biologically — the clans before you can get to the “confessional associations.”

why do i think weber was wrong about protestantism? many protestant sects — particularly in germany, but interestingly not in scandinavia nor, i think(?), in england (have to check that) — actually reversed the roman catholic church’s edicts on cousin marriage. iow, cousin marriage was once again allowed after luther’s day in large parts of europe (the specifics vary from place to place and time to time), so protestant europe was not the source of the breakdown of genetic ties in europe. it was the catholic church that got that ball rolling. i think that what many of the more ascetic, individualistic protestant sects were (are) were an expression of the newly forged individualistic natures of nw europeans. but, i could be wrong about that.

macfarlane’s quotes from weber come from weber’s “General Economic History,” so i guess that’s another book to add to the list. (^_^)

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