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! (^_^) )
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….”
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.
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.
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.
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
(note: comments do not require an email. altruism. what’s in it for me?)