THE BIOLOGY OF GEMEINSCHAFT
TÖNNIES’ CONTRIBUTIONS TO UNDERSTANDING POPULIST PLURALISM
One of the earlier sociologists that captured the transition from pluralist, organic communitarian society to the Janus-faced symbionts of individualism/statism was Ferdinand Tönnies. The German words he famously used in the title of his seminal book on the topic were gemeinschaft and gesellschaft. These terms have proven famously difficult to translate out of German. The standard English approach has been to resort to community and society, and indeed English translations have been usually published under that title. However, this is probably not a good translation.
One obvious problem with it is that, as Nisbet noted, community is a form of society. Society refers to the entity arising from social bonds. It has a range of references, including fellowship, association, alliance, union, and community. If, like Buber, we referred to the social tissue, binding a society together, we’d understand the term in this way. It is true that, in part inspired by these dubious translations of Tönnies, that term has gradually taken on the connotation of “mass society,” more in keeping with the idea of gesellschaft. But much too much is semantically (and semiotically) sacrificed by accepting this dubious association.
In fact, if you run the word “gesellschaft” through Google Translate, the translation it provides is “company.” It is true that the English uptake of “society” was at least in part from the original French usage to suggest something very similar to “company.” However, in English the connotations associated to the word “company” come much closer to what Tönnies was getting at than are those of the word “society.”
It is helpful in both common senses of the English word: referring to the company one keeps, as well as the use of the term displayed in the phrase “joint-stock company.” Company-based society, gesellschaft, is one in which social relationships are more formalized, negotiated, and contingent. Further, as we’ll see in the next post, following the analysis of Weber, these gesellschaft relationships are deeply rooted in rationalization (and the managerial class mobilized by such rationalization). I will use Tönnies’ own German terms in this discussion, but it was important to clarify those meanings for both those unfamiliar with the conventional English translations, and indeed for those who are familiar with them.
With that bit of semantic clarity established, I want to unpack here Tönnies core ideas on the topic. He is focusing right in upon the transition from temporal to spatial society, from organic community to the Janus-faced symbionts. So, his framing is terribly important both as a matter of seminal scholarship, but also as a frame for later generations’ understanding of what happened. While I believe his analysis provides great value, I consider it obvious that he wrote too early to benefit from the golden age of evolutionary biology research characterizing the 20th century. If we approach Tönnies’ treatment of the topic through that corrective lens, we wind up with an even more powerful and compelling explanation of both what happened in the transition and what that transition entails.
Early in his book, Tönnies provides some evocative comparisons between his two organizing concepts. He conceives of gemeinschaft as “real and organic” while conceiving of gesellschaft as “imaginary and mechanical.” He says: “There exists a Gemeinschaft of language, of folkways or mores, or of beliefs; but, by way of contrast, Gesellschaft exists in the realm of business, travel, or sciences.” And bearing in mind my suggestion that “company” is in fact a good translation for his use of gesellschaft, Tönnies says, “A young man is warned against bad Gesellschaft, but the expression bad Gemeinschaft violates the meaning of the word.” And likewise: “One keeps or enjoys another’s Gesellschaft, but not his Gemeinschaft in this sense.”
Tönnies observes that gemeinschaft “is the lasting and genuine form of living together. In contrast to Gemeinschaft, Gesellschaft is transitory and superficial. Accordingly, Gemeinschaft should be understood as a living organism, Gesellschaft as a mechanical aggregate and artifact.” Gesellschaft blossoms in urban settings, while gemeinschaft is the stuff of rural life. Without going into the details, I’ll observe that early in the book Tönnies is trying to establish a kind of physics-metaphor as the foundation to his argument. As I’ll demonstrate shortly, instead what he needs is a biological foundation, which is in no way metaphorical, but simply the explanation of the phenomena in question, as provided by the ultimate causation rooted in the inevitable fitness attraction intrinsic to the nature of any living entity.
In fact, Tönnies explicitly distances himself from biological explanations:
the present study does not deal with genus and species, i.e., in regard to human beings it is not concerned with race, people, or tribe as biological units. Instead, we have in mind their sociological interpretation, which sees human relationships and associations as living organisms or, in contrast, mechanical constructions.
This faulty reasoning, as I’ve mentioned, is likely the product of having written his book in the 1880s, prior to the golden age of evolutionary biology in the 20th century, and in fact at a time when even Darwin’s contributions were beginning to be re-evaluated in less generous terms, given the lack of further progress in establishing actual mechanisms. Though, this perception was a result of a failure to appreciate the relevance of Gregor Mendel’s research into heritability – a connection which, once made, became the foundation for the 20th century explosion in evolutionary research and theory.
I’ll start with a brief overview of Tönnies’ position, then backtrack to offer concrete illustrations of how biological knowledge, which of course he lacked when writing, provides a far sounder foundation for the dynamics he was observing. As mentioned above, he closely associates gemeinschaft with organicity, even though as we saw he distances himself from a distinctly biological explanation of this organicity. The drivers he sees at the heart of such dynamics are those of memory, sentiment, and habituation. People, either married or born into close association, develop memories, habits and feelings which give them a commonness of outlook that binds them together into gemeinschaft.
Here are some passages that make his claim:
The common root of this natural condition is the coherence of vegetative life through birth and the fact that the human wills, insofar as each one of these wills is related to a definite physical body, are and remain linked to each other by parental descent and by sex, or by necessity become so linked.
[Such linking is] represented in its most intense form by three types of relationships, namely: (1) the relation between a mother and her child; (2) the relation between husband and wife in its natural or general biological meaning; (3) the relation among brothers and sisters, that is, at least among those who know each other as being the offspring of the same mother.
[The] tendency toward [eventual mother-child] separation, however, can be counterbalanced, or at least restrained, by other tendencies, namely, through the mother and child becoming accustomed to one another and through remembrance of the pleasures which they have given each other, especially the gratitude of the child for the care and painstaking attention of the mother.
the relationship between man and wife, if considered independent from kinship and from all social forces based thereupon, has to be supported mainly by habituation to one another in order that the relationship may shape itself into one of mutual affirmation.
Among brothers and sisters there is no such innate and instinctive affection and natural liking or preference as between mother and children or between husband and wife.
The intellectual quality of this [sibling] relationship, as compared to the two others discussed above, is also apparent from the fact that, while instinct plays only a small part, the intellectual force of memory is the foremost in creating, conserving, and consolidating this bond of hearts.
It is…possible to deal with (1) kinship, (2) neighborhood, and (3) friendship as definite and meaningful derivations of these original categories.
Within kinship, all natural authority is concentrated in paternal authority; where the social grouping is based on neighborhood, this paternal authority is transformed into the authority of the prince and as such retains its importance.
Neighborhood describes the general character of living together in the rural village. The proximity of dwellings, the communal fields, and even the mere contiguity of holdings necessitate many contacts of human beings and cause inurement to and intimate knowledge of one another.
Friendship is independent of kinship and neighborhood, being conditioned by and resulting from similarity of work and intellectual attitude. It comes most easily into existence when crafts or callings are the same or of similar nature. Such a tie, however, must be made and maintained through easy and frequent meetings, which are most likely to take place in a town.
While Tönnies appreciates some kind of biological bond between the mother and child (though he seems somewhat uncomfortable with how much he can rely upon this bond as extenuating beyond the nuclear family), the husband-wife bond is more an act of will, though one deeply rooted in traditions of custom and common property. So, from his perspective, at least at the time of his writing, it was not a relationship which could be reduced to a contract. (Obviously, different from widespread perception, today.)
The father-child and sibling connections are the most tenuous for him but are forged and maintained through the memory and experience of living together and associated sentiments, perhaps especially in relation to the common sentimental attachment to the mother. It is these relationships which serve as the bond-model, we might say, of how gemeinschaft attachment can be expanded out into larger associations, such as clan or tribe, neighborhood, or friendship.
While all Tönnies talk of memory, habituation, and sentiment no doubt has some validity, it leaves open the questions of why such processes should be so important (or exist at all), much less what underpins them. So, they cannot act as foundations to his theory, but themselves require an ultimate explanation, which must be rooted in biology. The Rosetta Stone of human nature and behavior must be of course fitness.
Fitness in evolutionary biology refers to those traits, selected for retention in any species, which increases the species (or certain members of the species) success at producing offspring. Or, more precisely, at successfully ushering its genes into future generations. Any trait which facilitates such ushering constitutes fitness and is preferentially replicated in future generations via evolutionary selection. In any species any enduring trait is most likely to provide some such fitness benefit.1
So, with that Rosetta Stone on hand, let’s look again at some of Tönnies’ key claims in relation to the foundation and origins of gemeinschaft. As noted, his apparent discomfort with appeals to biology leaves him with an awkward identifying of the uniqueness of the mother-child relationship. Such unique bonding is widely observed, but understanding it requires a knowledge of evolutionary biology which wasn’t available to Tönnies. Simply stated, given humans’ altriciality and females virtually always having a higher investment in their offspring than do males – beginning metabolically with the production of more costly gametes and ratcheting from there with prior higher investments continually justifying further investment increases2 – it becomes predictable that mothers will have a more intense attachment bond with their offspring.
However, while males (by definition) almost always have lower investment, to say nothing of paternal uncertainty (a point I’ll return to shortly), among altricial species, males do have interest in offspring investment – especially under slower reproductive strategies. So, the male-offspring bond can be more intense and is more biologically grounded than Tönnies grants or appreciates. And, when he observes that “sexual relationships” do not guarantee permanent co-habitation among mates, while this is true, he doesn’t understand the strong propensity for such arrangements, especially among altricial species practicing slower sexual strategies. It is not, as he claims, strictly a product of habituation. And, in this regard, he is also under appreciating the fitness benefits of love.
Both sexes are subject to forms of parental uncertainty. This is perhaps more obvious in the case of paternal uncertainty, given that the offspring gestates within the female womb and it’s difficult for males to be sure that it was indeed their gametes which fertilized her egg, creating his genetic interest in the offspring. Females too though suffer a form of parental uncertainty as through most of human history females, due to the just addressed greater level of their investment in offspring, have an incentive to mate with males who are willing and able to help provide for her and her child. Ideally, some investment in the care and raising of the child would be even better. But males are of course able to mislead females about their intentions, and so can impregnate the female, but bail out on their promised investment.
Both sexes therefore have a risk in mating relationships. It appears that one adaptation to minimize such parental uncertainty has been the evolution of love. Sincere expression of devotion to the other may help mitigate the concern about abandonment for females or cuckoldry for males. Love, then, as some would put it, is not some ephemeral, imaginary notion, but rather a biological manifestation (the neurochemical composition of love in the brain is known) for contributing to the resolution of potentially serious mating obstacles.
This same love, also experienced by parents toward their offspring (again, the same neurochemical processes), is a vitally important part of the family bond. It is not the only one, though. And it is probably even more this other dimension of family bonding which Tönnies needed to understand for him to appreciate how the family bond extended to a wider community.
This other dimension is the remarkable human capacity to recognize genetic similarity. As with everything cognitive, such processes are conducted through evolved mechanisms, which sometimes are called modules, and in my own work I’ve called PCBM (perceptual-cognitive-behavioral mechanisms). Unlike a still common, strangely romantic idea of the human mind, which imagines some homunculus inside our brains making our decisions and judgments for us, in fact such decisions and judgments are produced by the heuristic operation of these PCBM.3 And, as they do operate heuristically, they can be fooled. A famous example of such heuristic failure is in the case of manifest sibling incest disgust among genetically unrelated siblings raised in the same household from an early age.
The fitness benefits from the evolution of sibling incest disgust should be obvious; it reduces the likelihood of birth defects which are much more likely to arise in such reproductive contexts. However, there would be no particular risk of such outcomes among “siblings” who are not sufficiently genetically related to incur such risk – either via a stepparent or adoption. In fact, given the convenient physical proximity, such a “sibling” of the opposite sex would be an unusually promising reproductive mate.
However, if the children grow up together from sufficiently young an age, they tend to experience the same, adaptive, sibling incest disgust which would be adaptive if they were genetic siblings.4 Whatever the heuristic at work here, it seems to have been fooled by either proximity or some other aspect of context. Such heuristics, though, do not gain their advantage from universal accuracy, but merely from the marginal advantage of statistical benefits – played out over an evolutionary time scale.
The value of being able to recognize genetic relatedness was demonstrated, and its fitness enhancing value explained, in the 1960s by a couple of landmark papers by William Hamilton.5 Situations, such as animals that give warning calls (putting themselves as individuals at greater risk) upon approach of a predator, were able to be explained then in terms consistent with evolutionary theory.
If an individual can protect more copies of its own genome (or portions thereof) through risking the sacrifice of its own life, there would be fitness pressures to select for that behavioral trait. Hamilton called this tendency inclusive fitness. It is the root of the widely acknowledged and practiced forms of extended family nepotism. This argument for inclusive fitness has been pretty much universally accepted and adopted across evolutionary biology as one of the field’s most important, pioneering insights.
However, and this is where the story becomes especially important for understanding the organic nature of gemeinschaft, in later work of the 1970s Hamilton recognized how these dynamics of inclusive fitness in fact were not necessarily restricted to a level of familiarity associated with the family.6 He went on to argue in those later papers that even though non-kin of the same ethnicity7 shared too little genetically to generate such kin selections effects, nonetheless, such ethnicities do share enough common genes, compared to outgroups which might replace them, that if enough copies of their ethnicity’s genomes were at stake – and so a statistically significant probable enough portion of their own genes – behavior that mitigated this replacement would be fitness enhancing and so there could be evolutionary pressures to select for such behavior.8
As genetic distance increases between ethnic populations, the kinship coefficient between randomly selected co-ethnics grows. This may well be the evolutionary root of the well-known human propensity for in-group preference. A considerable amount of evidence has accumulated to suggest that ethnic in-group preferences may be selected for and operating at the level of PCBM. People are more charitable to co-ethnics and better disposed to forming alliances of various kinds with them. Support for welfare state initiatives erode in contexts where people may see their tax dollars being used to provide privileged aid to another ethnicity and there is general decline of support for public goods in such areas of mixed ethnicity, leading to lower levels of voting, volunteering, and charitable giving.9
All of this, of course, is premised upon our striking capacity to recognize genetic similarity. Again, as was seen above, whatever exactly are the heuristics being used to recognize such similarity need not be, and likely are not, perfect. They only need to be sufficiently good to gain the fitness advantage that comes from inclusive fitness, even when extended to a larger group. This recognition ability was documented in the work of Phillippe Rushton.
For instance, research revealed that people are inclined to choose spouses and best friends who are more genetically like themselves. Not only are they more inclined to choose people with similar traits, but that tendency is increased for those traits that are more heritable: have a higher likelihood of being passed on as fixed genetic effects. Also, monozygotic twins, who share essentially the same genome, are more likely to choose spouses and best friends who are more like each other. Interestingly, even in ethnically mixed marriages it turns out that people choose spouses with whom they share more heritable traits, such as intelligence. It’s also noteworthy that this explanatory lens is more effective than a cultural theory which would predict that spouses and friends over time would grow to resemble each other, since there is less similarity in traits that might change over time, through for instance lifestyle choices, than in the highly heritable ones that do not change.10
Such correlations suggest, along the lines of Hamilton’s analysis, an evolved disposition, based on some kind of PCBM-based heuristic, to favor our own genes when found in non-kin. Some other research pointing in this direction is that when asked to identify the most attractive face from a mosaic of opposite sex faces, people are more likely to choose a morphed version of their own face that has been included in the options. To rule out the variable of superficial familiarity, the morphed faces of celebrities were included. Still, people are more attracted to facial similarity, which serves as a proxy of genetic similarity.11 Even more interesting, because more discriminating, is the role of scent in identifying genetic similarity. Female mating preferences based on male scent reveal a preference for genetically similar men over those totally dissimilar to them. In keeping with the need to avoid the dangers of recessive gene effects, though, the women preferred the scent of genetically similar men to the scent of men who were nearly genetically identical to them.12
All this research points to two remarkable and essential human characteristics relevant to understanding the organic nature of gemeinschaft. First, humans have an evolutionary fitness enhancing interest in favoring those sufficiently genetically similar to themselves when in conflict with, or perceived to be in danger from, others who are less genetically similar. And second, whatever the exact mechanism – as far as I know there’s no consensus on this still – humans have a statistically empirical ability to identify and privilege genetic similarity in their social interactions and relationships. As a heuristic, this capacity is not perfect, it can be fooled, it even can be hacked, but it’s plenty effective enough to statistically manifest well beyond random. Therein lies the marginal advantage which allows for selective retention.
It is in this way that it is perfectly accurate to describe gemeinschaft and its forms of community as “organic” in a way which is not to be confused as metaphorical. I think it would be wrong to entirely dismiss the roles of habituation, memory, and sentiment upon which Tönnies places so much emphasis. When the genetics and evolutionary biology, to which of course he had no access in the 1880s, are taken account of though, these factors become either symptoms of evolutionary fitness or aspects of ontogenesis – which is of course itself ultimately an expression of evolutionary fitness.13
So, again, it is not a metaphor to refer to gemeinschaft and its community as organic. It is organic at the molecular level of genetic relatedness. Further, it is likely that where Tönnies is onto something important is that certain kinds of physical contexts either reinforce or otherwise stimulate heuristic processes that look for genetic similarity. Though, I’ll hedge that claim as merely speculative at this point. All this though, hopefully, one can see is a world apart from the experience of gesellschaft, with its undermining of organic community through formal relations and rational processes.
At this point, it’s worth mentioning that Tönnies characterized gesellschaft as artificial, rather than natural, as a form of social order. Interestingly, disagreement over this characterization was fleshed out in a pair of competing book reviews by Tönnies and another pioneering giant of sociology, Emile Durkheim. Durkheim, who liked the distinction between these two kinds of social orders, argued though that gesellschaft was in fact just as natural as was gemeinschaft.14 Certainly, insofar as one considers the extended phenotype productions of animals, e.g., the nests of birds or the hives of bees, as “natural,’’ it hardly makes sense to regard administrative bureaucracies or stock market exchanges as unnatural. Still, one can understand Tönnies’ point. To put it in 20th century language, gesellschaft may be natural in the extended phenotype sense, but it isn’t organic, in the molecular genetics sense.
Gesellschaft was characterized by the coming together into common spaces and forms of association which did not control for degrees of genetic relatedness. This would have been true in even medieval towns, where most of the population was still coming from the regional rural surroundings. Such inhabitants did not share nearly so close a genetic relation with their urban neighbors, customers, and colleagues as they did back in the rural gemeinschaft communities from which they’d come. Though they’d still have had a closer gemeinschaft connection than they’d have with those in more distant towns. And once gesellschaft sensibilities manifest into large cities, by the 19th century some with a million or more inhabitants, including people from all over the continent and even from other continents, any pretense of genetic common fitness interest binding social interaction became an absurdity.
Of course, within the mass city people may seek out those more genetically related to them. This could be in the more salient form of urban neighborhood villages, along the lines of the 19th-20th centuries’ Chinatowns and Little Italies. Or less salient, in the form of fraternal clubs and sporting leagues. But even with these, as the cities became more dense, complex, and integrated, it became inevitable that the average resident’s daily, street level encounters were almost exclusively among others with whom he had shared no close genetic connection. Genetic distance became the norm. This is what made such an environment a gesellschaft, in contrast to the closer bonds of the gemeinschaft.
It is in this context then that we clearly see the most developed form of gesellschaft as by necessity organized around formal and rational institutions and practices in law, markets, and administration. Herein is the key biological distinction between gemeinschaft and gesellschaft: one is rooted in shared genetic interest, the other in more individualized genetics arising from the prospects of rational exchange and contract. And once understood this way, the gemeinschaft-gesellschaft distinction dovetails elegantly with Innis’ distinction between time and space biased societies. The shift from gemeinschaft to gesellschaft is a shift from the influence and power of, as I’ve put it, the temporals to that of the spatials. Tönnies’ book provides both theoretical and empirical support for Innis’ analysis.
However, there is an important difference between Tönnies’ and Innis’ historical sociologies. Tönnies believed that the movement from gemeinschaft to gesellschaft was a unidirectional one; once a society crossed that Rubicon there was no going back. Innis, on the other hand, as we’ve seen, not only believed that there was a pendulation involved in the dynamics between these two kinds of social order; he believed that some movement back in the direction of balance between these tendencies (time/gemeinschaft and space/gesellschaft) was essential as a condition of civilizational survival.
Tönnies’, though, was not the last word on the contribution of classic historical sociology to a fleshing out of Innis’ civilizational theory. Better understanding of both the specific dialectic of this distinction – treated by Tönnies as a unidirectional dichotomy – and gesellschaft’s distinctly rational, non-organic dynamism, profits from considering the insights of yet another giant of early sociology who also turned to this topic, Max Weber.
And that’s next on the agenda. So, if this is the kind of thing that turns your proverbial crank, and you haven’t yet, please…
And if you know any fellow travelers in these intellectual spaces, please…
That’s the extent of the biological explanation that I’ll provide here. Among the many places one can look for more elaborate and in-depth explanations for all this is my own book, Michael McConkey, Biological Realism: Foundations and Applications (Vancouver, B.C.: Biological Realist Publications, 2020).
Robert Trivers, “Parental Investment and Sexual Selection,” in Sexual Selection and the Descent of Man, 1871-1971, ed. B. Campbell (Chicago: Aldine Transaction, 1972).
For a good introduction to the operating of the human mind see Robert Kurzban, Why Everyone (Else) Is a Hypocrite: Evolution and the Modular Mind (Princeton, N.J.: Princeton University Press, 2010). For my discussion of PCBM, see McConkey, Biological Realism: Foundations and Applications.
Daniel M. T. Fessler, “Neglected Natural Experiments Germane to the Westermarck Hypothesis,” Human Nature 18, no. 4 (October 2, 2007): 355–64, https://doi.org/10.1007/s12110-007-9021-1; Delphine De Smet, Linda Van Speybroeck, and Jan Verplaetse, “The Westermarck Effect Revisited: A Psychophysiological Study of Sibling Incest Aversion in Young Female Adults,” Evolution and Human Behavior 35, no. 1 (January 1, 2014): 34–42, https://doi.org/10.1016/j.evolhumbehav.2013.09.004; Robert A. Wilson, “Incest, Incest Avoidance, and Attachment: Revisiting the Westermarck Effect,” Philosophy of Science 86, no. 3 (July 1, 2019): 391–411, https://doi.org/10.1086/703572.
W. D. Hamilton, “The Genetical Evolution of Social Behaviour. I,” Journal of Theoretical Biology 7, no. 1 (July 1964): 1–16, https://doi.org/10.1016/0022-5193(64)90038-4; W. D. Hamilton, “The Genetical Evolution of Social Behaviour. II,” Journal of Theoretical Biology 7, no. 1 (July 1964): 17–52, https://doi.org/10.1016/0022-5193(64)90039-6.
W. D. Hamilton, “Selection of Selfish and Altruistic Behavior in Some Extreme Models,” Man and Beast: Comparative Social Bahavior, 1971, 57–91; W. D. Hamilton, “Innate Social Aptitudes of Man: An Approach from Evolutionary Genetics,” Biosocial Anthropology 133 (1975): 115–32. Hamilton’s papers of the 70s are either cursorily dismissed or, more often, just ignored. Liberals like Dawkins and Pinker lionize Hamilton for his 1960s papers precisely because they offer a plausible alternative explanation for altruism which avoids the collectivist stench of group selection arguments of the mid-20th century, and so complement the radical individualism taken as implicit in the selfish gene hypothesis. However, when Hamilton applied the exact same principle that he identified in his inclusive fitness papers — i.e., if there is a sufficient number of one’s gene copies at risk it would be fitness enhancing for the ability to recognize and preserve them to be selectively retained — to larger groups, such as races and ethnicities, this was completely out of bounds. When his math seemed to support their liberal bias, he was a hero; when the same math challenged their liberal bias, he was a zero.
Ethnicity is a bit of a tricky term, so let’s just say for now we’re using it to refer to an identity which is more material than facultative.
Much of this paragraph and the next three are drawn from my book, Biological Realism, which also provides important context for such a discussion.
Frank Salter, On Genetic Interests, 1 edition (New Brunswick, N.J: Transaction Publishers, 2006); Frank Salter, ed., Welfare, Ethnicity and Altruism: New Data and Evolutionary Theory, 1 edition (Routledge, 2013); Robert D. Putnam, “E Pluribus Unum: Diversity and Community in the Twenty-First Century: The 2006 Johan Skytte Prize Lecture,” Scandinavian Political Studies 30, no. 2 (June 1, 2007): 137–74, https://doi.org/10.1111/j.1467-9477.2007.00176.x.
J. Philippe Rushton, Robin J. H. Russell, and Pamela A. Wells, “Genetic Similarity Theory: Beyond Kin Selection,” Behavior Genetics 14, no. 3 (May 1, 1984): 179–93, https://doi.org/10.1007/BF01065540; Denise Daniels and Robert Plomin, “Differential Experience of Siblings in the Same Family,” Developmental Psychology 21, no. 5 (1985): 747–60, https://doi.org/10.1037/0012-1649.21.5.747; J. Philippe Rushton, “Genetic Similarity, Human Altruism, and Group Selection,” Behavioral and Brain Sciences 12, no. 3 (September 1989): 503–18, https://doi.org/10.1017/S0140525X00057320; J. Philippe Rushton, “Ethnic Nationalism, Evolutionary Psychology and Genetic Similarity Theory,” Nations and Nationalism 11, no. 4 (2005): 489–507, https://doi.org/10.1111/j.1469-8129.2005.00216.x; J. Philippe Rushton and Trudy Ann Bons, “Mate Choice and Friendship in Twins: Evidence for Genetic Similarity,” Psychological Science 16, no. 7 (July 1, 2005): 555–59, https://doi.org/10.1111/j.0956-7976.2005.01574.x; Helmuth Nyborg, ed., The Life History Approach to Human Differences: A Tribute to J. Philippe Rushton (London: Ulster Institute for Social Research, 2015).
I. S. Penton-Voak, D. I. Perrett, and J. W. Peirce, “Computer Graphic Studies of the Role of Facial Similarity in Judgements of Attractiveness,” Current Psychology 18, no. 1 (March 1, 1999): 104–17, https://doi.org/10.1007/s12144-999-1020-4.
Suma Jacob et al., “Paternally Inherited HLA Alleles Are Associated with Women’s Choice of Male Odor,” Nature Genetics 30, no. 2 (February 2002): 175–79, https://doi.org/10.1038/ng830.
Again, to fully appreciate such claims one needs to read McConkey, Biological Realism.
Joan Aldous, Emile Durkheim, and Ferdinand Tönnies, “An Exchange Between Durkheim and Tönnies on the Nature of Social Relations, with an Introduction by Joan Aldous,” American Journal of Sociology 77, no. 6 (May 1972): 1191–1200, https://doi.org/10.1086/225264.