Because of its uniqueness, Western individualism presents a daunting question for scholars and in particular for a theory based on evolutionary psychology. There are essentially two ways for an evolutionary perspective to attempt to understand uniqueness. One is to propose a unique evolutionary environment resulting in genetically based uniqueness; the other is to propose universal psychological mechanisms interacting with particular cultural contexts. Jonathan Schulz et al.’s “The Church, Intensive Kinship, and Global Psychological Variation” is an example of the latter. It presents a theory of Western individualism in which the cultural context created by the medieval Catholic Church, particularly the prohibitions on relatedness in marriage, played a central role in the development of the individualistic psychology of the West. More precisely, the paper attempts to explain “a substantial portion” of the variation in psychological traits widely recognized to be characteristic of individualism (“individualistic, independent, analytically minded, and impersonally prosocial [e.g., trusting of strangers] while revealing less conformity, obedience, in-group loyalty, and nepotism”) by exposure to the medieval Western Church. Within this cultural framework, there is no attempt to present the motivations of the Church for creating this cultural context in terms of particular psychological mechanisms.
These issues intersect with much of the discussion in my recently published Individualism and the Western Liberal Tradition: Evolutionary Origins, History, and Prospects for the Future. However, my theory is based on the proposal that Western uniqueness derives ultimately from unique ancestral environments in northwestern Europe, with emphasis on a north-south genetic cline in the relative genetic contributions of northern hunter gatherers, Indo-Europeans, and Early Farmers from the Middle East. While Schulz et al. control for a wide range of variables, they do not control for regional genetic differences within Western Europe that have been uncovered by recent population genetic research (reviewed in my Chapter 1), nor do they review research by family historians indicating important regional variation within Western Europe that does not at all map onto exposure to the Western Church (reviewed in my Chapter 4).
However, I do discuss the influence of the Western Church, concluding that the Church’s
influence was directed at altering Western culture away from extended kinship networks and other collectivist institutions, motivated ultimately by the desire to extend its own power [analyzed as an evolved human universal]. However, although the Church promoted individualism and doubtless influenced Western culture in that direction, this influence built on individualistic tendencies that long predated Christianity and were due ultimately to ethnic tendencies toward individualism unique to European peoples (Chapters 1–4). [From Chapter 5, 170]
My approach thus combines pre-historic natural selection for individualist psychology with particular cultural contexts, one of which is the influence of the Catholic Church, the latter interpreted as building on pre-existing tendencies. My Chapter 5 on the medieval Church argues, on the basis of data similar to that cited by Schulz et al., that the Church facilitated individualism—and may well have sped up the establishment of individualism, but did not cause it. Given that Schulz et al. claim to have achieved only a partial explanation, there is thus no fundamental disagreement. However, based on my treatment, here I attempt to show why exposure to the medieval Church is an inadequate explanation of psychological individualism in the West.
There is much that our approaches have in common. In particular, they note that kinship relationships are central in understanding human societies and that the general trend has been a shift away from extensive kinship relationships typical of hunter-gatherers throughout the world (i.e., relatively weak ties to many people of varying genetic distance—discussed in my Chapter 3) to intensive kinship relations (i.e., kinship deeply embedded within closely related groups, e.g., clans and kindreds with a distinct hierarchy based on degree of genetic relatedness) commonly found in agricultural societies.
However, I also provide evidence that Western individualism was influenced by genetic differences peculiar to the peoples of Western Europe. I show on the basis of historical and contemporary population genetic data that there is a genetic cline from north to south in Western Europe in which hunter-gatherer genes (and Indo-European-derived genes; see below) are more prevalent in the north of Europe. Importantly, the northern European hunter-gatherers retained their relatively extensive kinship patterns while nevertheless creating complex societies with large populations able to hold off agriculture for 2000–3000 years against the farming culture originating from the relatively collectivist Early Farmers who arrived in southern Europe from the Middle East ~8500 years before present. Areas in Western Europe with greater representation of Early Farmer genes (e.g., 90 percent in Sardinia and higher in the south of France than in the north) exhibit relatively collectivist family structures, continuing into the present.
The basic argument is that traditional agricultural societies based on intensive kinship were centered around defensible resources, such as large river valleys, like the Yangtze, Nile, and Euphrates, capable of being controlled on a year-around basis by a kinship group. This was not possible in the north of Europe. Groups congregated for part of the year near a highly productive resource—the seashore and its supply of shellfish and other marine life—but were forced to disperse into small family-based groups for part of the year.,  And because of the relatively harsh northern environment, there was selection for a suite of psychological traits conducive to paternal provision of offspring, bilateral kinship relations, and monogamy (pair-bonding), whereas polygyny (acknowledged by Schulz et al. as a marker of clan-based cultures) by wealthy, powerful males able to set up households consisting of multiple, closely related families, would be ecologically impossible. Whereas an individual’s position in societies based on intensive kinship depends on status in a strongly hierarchical kinship group, hunter-gatherer cultures are much more egalitarian, with strong controls against despotic leadership. Moreover, as Michael Burton et al. note, the circumpolar cultural area, including northern Europe but also a diverse group of northern cultures (e.g., Japan, Korea, the Inuit, Lapps), tends toward bilateral kinship relations which result in an extensive set of kinship relations. Schulz et al. correctly regard bilateral kinship relations as an aspect of extensive kinship relations, but I interpret these data as supporting a primordial, genetically influenced, climate-based theory of kinship intensity rather than as due to Church influence given that bilateral kinship relations also occur in northern non-Western societies.
Schulz et al. thus fail to note pre-existing tendencies toward extensive kinship among northern hunter-gatherers continuing into the present. They also fail to note features of Indo-European culture as it developed in Europe that militated against a strong role for intensive kinship (discussed in my Chapter 2). The Indo-European-based cultures that dominated Europe until the Protestant Reformation and the decline of the aristocracy were an amalgam of “Armenian-like” Near Eastern peoples (48–58 percent) with three northern hunter-gatherer groups: Caucasus hunter-gatherers, Ancient North Eurasians (including Siberia), and Eastern hunter-gatherers (Chapter 1). Indo-European-derived cultures were never based on the clan-type, intensively kinship-oriented cultures common, say, in the Middle East:
In jahili and early Islamic poetry we find men, women, and children who defined themselves not as individuals but as kin. In short, whether one was an oasis-dweller or a resident of the highlands of Yemen, a pastoral nomad, or someone whose way of life fell somewhere between settled and nomadic, it was kinship—one’s family, one’s clan, one’s tribe—that defined who one was. The issue of kinship remained important even in the cosmopolitan urban worlds of medieval Damascus, Baghdad, Cairo, and elsewhere. It continues in many Islamic societies today.[6a]
Rather, Indo-European culture had important elements of a free-market, with a strong role for reciprocity within the group and institutions above the level of kinship-based groupings. Upward mobility was dependent on military talent, not on kinship relations, especially being able to recruit followers able to effectively conquer and hold territory. Individualistic competition for lasting fame and glory was a defining feature. As Ricardo Duchesne notes, Indo-European heroes in ancient Greece and elsewhere in the West were individuals first and foremost—men who distinguished themselves from others by their feats in pursuit of individual renown, as shown by these lines from Beowulf:
As we must all expect to leave / our life on this earth, we must earn some renown, /If we can before death; daring is the thing /for a fighting man to be remembered by. /… A man must act so / when he means in a fight to frame himself / a long lasting glory; it is not life he thinks of. [From Chapter 2, 46–47]
Thus, within the Männerbünde, “the warrior brotherhood bound by oath to one another and to their ancestors during a ritually mandated raid,” status was determined by military talent, not kinship connections. In such a culture, intensive kinship had at best a secondary role—these cultures never developed into the clan-based cultures typical of so much of the rest of the world. Although kinship retained some importance, the Männerbünde existed at a higher level than kinship-based groups and functioned partly to settle disputes among them.
The aristocratic individualism of the PI-Es [proto-Indo-Europeans] was based on reciprocity, not despotism or kinship ties. For example, at the heart of PI-E culture was the practice of gift-giving as a reward for military accomplishment. Successful leaders were expected to reward their followers handsomely. Oath-bound contracts of reciprocal relationships were characteristic of PI-Es and this practice continued with the various I-E groups that invaded Europe. These contracts formed the basis of patron-client relationships based on reputation—leaders could expect loyal service from their followers, and followers could expect equitable rewards for their service to the leader. This is critical because these relationships are based on talent and accomplishment, not ethnicity (i.e., rewarding people on the basis of closeness of kinship) or despotic subservience (where followers are essentially unfree). [From Chapter 2, 35]
Oath-bound contracts, reciprocity, and reputation—all markers of individualism—were thus critical. Moreover, conquered peoples were not eradicated, and, after varying periods of time, upward mobility was typically possible for conquered peoples if they had military talent. The walls that separated conquerors from the conquered in terms of marriage, citizenship, and social status were eventually breached—a marker of individualism because, again, individual talent was critical, not kinship connections. Within Europe at least, conquering Indo-Europeans did not erect barriers of permanent separation from those they had conquered; they did not create a social structure based on intensive kinship that endeavored to separate itself permanently from those they conquered, as depicted, for example, in the Old Testament and continuing in present-day Israel vis-à-vis the Palestinians. For example, ancient Rome, a prototypical variant of Indo-European militarized culture, absorbed the peoples they conquered and recruited them for military service, thus allowing Rome to expand enormously. However, these conquered peoples typically achieved citizenship eventually and many even achieved high status within Roman society, assuming high political and military office.
From the earliest period of the Republic, there are examples of the social fluidity of the Roman aristocracy. Appius Claudius came to Rome from Sabine territory in 509 bc and became a member of the patriciate. L. Fulvius Curvus, from Tusculum became consul 60 years after Rome conquered Tusculum in 381 bc. …
Openness to foreigners can also be seen in that Latium, comprising the nearby towns with similar language and culture, had rights of commercium (could own property in other towns), connubium (marriage), and migrandi (migration). This set a precedent for later times, when other, non-Latin peoples would be incorporated into Roman society with partial citizenship (civitas sine suffragio). Such peoples might later be upgraded to full citizenship: e.g., the Sabines were upgraded from civitas sine suffragio to full citizenship in 268 bc. This openness to other peoples was “a key element in Rome’s later imperial success.” [Inner quote from Gary Forsythe’s A Critical History of Early Rome; from the Appendix to Chapter 2, 79, 80]
A defining feature therefore of Indo-European-derived cultures in Europe was the permeability of groups, as individuals were free to defect to other groups with greater possibility of success. Primordially individualist competition was in military ventures, but later occurred in other forms of competition in which groups were permeable and defection possible, including intellectual competition characterized by group permeability—a prerequisite for science.
Ricardo Duchesne highlights disputation as a critical component in Western intellectual discourse, analyzed in terms of the Indo-European cultural legacy of personal striving for fame. Beginning in ancient Greece, intellectual debate was intensely competitive, and individuals were free to defect from a particular scholar if they found another more appealing. Intellectuals sought followers not by depending on pre-existing kinship or ethnic connections, but rather by their ability to attract followers in a free market of ideas in which people were free to defect to other points of view. Just as members of a Männerbund were free to defect to other groups with objectively better prospects for success, the free market of ideas would naturally default to arguments and ideas that can appeal to others who are free to defect from the group and where groups are highly permeable. In a social context consisting of others who are similarly free to defect, logical arguments and predictive theories about the natural world would come to the fore. (From Chapter 9, 482–483)
Similarly, capitalism presupposes individualist economic competition and the ability of individuals to defect from purchasing particular products or investing in business ventures if they find a better opportunity.
Sources and Targets of Church Power
Schulz et al. see exposure to the Western Church as a critical variable in the development of Western individualism and emphasize the Church’s rules on incestuous marriage. My discussion of Church influence is much broader. I discuss other Church policies that facilitated individualism, most importantly creating an image of reproductive altruism by enforcing clerical celibacy and ending corruption as a result of the Papal Revolution beginning in the tenth century and completed by the High Middle Ages. This image was a necessary development for producing the intense religious fervor and popular loyalty of the period, thus enabling the Church to have significant power over secular elites fearful of being excommunicated and thus losing legitimacy in the eyes of their people.
Along with the acceptance of celibacy and asceticism, there was a concern to extend the power of the church—“a powerful movement to gain command of all life in society and organize it according to monastic views.” It is this drive to increase its own power at the expense of other potential sources of power—kings and the aristocracy, extended kinship groups—that best explains the behavior of the medieval Church. This desire for power is a human universal entirely congruent with evolutionary thinking, except that in this case, it was not accompanied by the usual accouterments of power [typically seen in clan-based cultures]: reproductive success and control over women. [from Chapter 5, 186]
Church policies directed against the power of secular elites focused on marriage as an essential battleground, including, besides rules on incestuous marriage, developing ideologies and enforcing social controls supporting monogamy, preventing divorce, preventing bastards from inheriting. Particularly important was enforcing consent as the basis of marriage (not considered by Schulz et al.). Consent in marriage promotes individualist marriage choice based on the characteristics of spouse rather than family strategizing in which one’s spouse is determined by parents, with the result that “the family, the tribe, the clan, were subordinated to the individual. If one wanted to marry enough, one could choose one’s own mate and the Church would vindicate one’s choice.
The Church also developed ideologies of moral egalitarianism and moral universalism that undermined the ideology of natural hierarchy typical of the ancient world, and often encouraged the emerging cities as independent power centers opposed to the interests of feudal lords. Regarding the ideology of moral egalitarianism:
Canon law … had a strongly egalitarian tenor—status, which had been central to ancient law—was irrelevant. Ecclesiastical ideology thus facilitated the Western liberal tradition. Aristocrats and commoners had the same moral standing. Moreover, canon law was recruited to lessen the power of kinship groups by also rejecting the privileged status of testimony from family and friends (which had led to more powerful families getting favorable judgments). [From Chapter 5, 188; emphasis in original]
However, it is not the case that the Church invented monogamy as the norm for Western marriage:
Whereas all of the other economically advanced cultures of the world have been typified by polygyny by successful males, Western societies beginning with the ancient Greeks and Romans and extending up to the present have had a powerful tendency toward monogamy. Thus the Catholic Church cannot be seen as originating monogamy, but, as indicated in the following, it did have a central role in maintaining monogamy at least through the Middle Ages.
The Catholic Church was the heir to Roman civilization where monogamy was ingrained in law and custom, and during the Middle Ages it took it upon itself to impose monogamy on the emerging European aristocracy. Relatively low-level polygyny (in comparison to other societies based on intensive agriculture such as China, India, the Middle East, and Meso-America) did exist in Europe, and during the Middle Ages it became the object of conflict between the Church and the aristocracy. The Church was “the most influential and important governmental institution [of Europe] during the medieval period,” and a major aspect of this power over the secular aristocracy involved the regulation of sex and reproduction. [From Chapter 5, 176–177]
How Widespread Was Obedience to the Church’s Rules on Incestuous Marriage?
Given the importance of the rules on incest for Schulz et al.’s account, it is important for them to show that the Church’s policy had real effects—that incestuous marriage declined from previous levels after the rise of the Church. Schulz et al. measure the rate of cousin marriage only in the twentieth century, not during the Middle Ages. As a result, they do not provide data on the effectiveness of the Church policy, a critical lacuna in their account because if in fact cousin marriage was never common in the West, there is little reason to believe that the elaborate rules surrounding incestuous marriage had a decisive role. And, if so, an account that takes into account primordial ethnic tendencies becomes more plausible. Here I cite some relevant scholarship indicating that exogamy was the norm in the West dating at least from Roman times and likely long before.
Given that the Indo-European conquering groups were based on predatory male bands (the Männerbünde), marriage was thus likely to be exogamous. This is supported by the relatively high presence of Indo-European (Yamnaya-derived) Y-chromosomes in ancient DNA from the Corded War culture of much of northern Europe ~5000 years ago (Chapters 1 and 2). Mutations for eye and hair color unique to Europe are likely to be due to sexual selection for marriage by individual choice of mate characteristics rather than marriage with relatives and family strategizing,, and I make a similar argument for the greater role of love as a basis of marriage in the West compared to societies based on intensive kinship relations (Chapter 3).
Regarding the Western Roman Empire, quoting Brent D. Shaw and Richard P. Saller:
There is strong evidence for continuity of the general practice of exogamy in the western Roman empire from the pre-Christian period (first three centuries after Christ) to the era of the establishment of Christianity as the state religion; endogamous marriage was rare, if it occurred at all. Despite legal rules permitting cousin marriage in the pagan era, parallel and cross-cousin marriages were rare among aristocrats, as were parallel-cousin marriages among modest inhabitants of the western empire. Consequently, the Christian ban on marriages within the sixth degree of kinship had little impact. The dispersed pattern of property holding offered pagan aristocrats no incentive to marry within the family to protect consolidated estates; their financial interests were met by marriage within the same class. … The Church’s ban on endogamy should not be interpreted as part of an effort to disrupt transmission of property within the family: no such effort was necessary because for centuries pagan aristocrats had been using the will to disperse their wealth widely. The Church need only have replaced the emperor as the principal institutional beneficiary of these wills in order to enrich itself. …
In sum, when the Church moved to formalise an extended incest prohibition in the fourth century, it was not acting to disrupt a widespread practice of close-kin endogamy in the western Roman empire. In fact, Augustine, in his discussion in the City of God concerning the recent extension of the incest rule, clearly indicates the opposite. He states categorically that marriage between cousins always had been raro per mores (‘rare in customary practice’), well before the imposition of the new prohibitions. [Quoted in Chapter 4, 128–129]
Further, I note:
Whatever the rationale given to these prohibitions by the Church, there is evidence that the aristocracy obeyed the ecclesiastical rules [during the tenth and eleventh centuries]. There were very few marriages closer than fourth or fifth cousins among the French nobility of the tenth and eleventh centuries. These practices weakened the extended kinship group, since the expanded range of incestuous marriages prevented the solidarity of extended kinship groups by excluding “the reinforcing of blood with marriage.” The result was that biological relatedness was spread diffusely throughout the nobility rather than concentrated at the top. The direct descendants of the family rather than the wider kinship group also benefited: “Men in high secular positions … strove to consolidate their fortunes and their families in order to secure as much as possible for their direct descendants to the detriment of wider kin.” [From Chapter 5, 210–211]
The important point in the above passage is that the aristocracy obeyed the rules on incest in the tenth and eleventh centuries—not surprising given that the Church directed its campaign to achieve power mainly at elite power centers, especially the aristocracy, not the commoners. After all, males with little wealth or power could hardly expect to be polygynous or have concubines, both of which would violate the ecclesiastical view of marriage. I know of no evidence that those of more modest means avoided marriage within the six degrees of relatedness. All of the cases cited by C.B. Bouchard in which the Church railed against incestuous marriage were from the nobility. For example, the Capetian kings of France were forced to accept Russian women and eventually to lower their standards for appropriate rank to daughters of counts and other lesser nobles.
Indeed, in the relatively small, isolated communities of traditional Western Europe—where highly circumscribed regional dialects were common and people had little mobility—people perforce married within the local community and could thus hardly avoid marrying someone without a common great-great-great-great-great grandfather.
Elizabeth Archibald’s Incest in the Medieval Imagination further contextualizes these findings. In a comment that applies to the general population rather than only the nobility, she notes that “in practical terms, the seventh degree, the extent of memory, and all known kin probably came to mean much the same thing for many people in the Middle Ages.” Given that most people would necessarily choose partners locally, it would have been impossible to honor the Church’s rules, since “… the list of possible partners with whom sex was prohibited must have covered every possible partner in many small communities … .” Further the discussion of actual cases shows little concern with the seven degrees of relatedness but much concern with near blood relatives (e.g., uncle, niece) or affinal relatives. In general:
However much the Church rationalized its position and strove to enforce it, it is evident from ecclesiastical correspondence, court records, and well-known scandals of the time that the rules were ignored or honoured in the breach by many Christians during the Middle Ages, or were manipulated for personal advantage to get around the principle of the indissolubility of marriage. … In spite of the determination with which the Church insisted on its complex rules of who could marry whom, the ecclesiastical authorities were remarkably lenient in interpreting many parts of the incest legislation, especially in regard to more distant relations and affines. It is also clear that many people in the Middle Ages were not particularly bothered by breaches of the incest rule, such as the marriage of second cousins.
It’s noteworthy that after the tenth and eleventh centuries the French aristocracy was widely known to flout the rules on incest, being well aware they were marrying incestuously in the eyes of the Church, but invoking these rules in the event of desiring a divorce. Thus the rule-following in the tenth and eleventh centuries by secular elites did not fundamentally alter their psychology. Moreover, this “convenient escape hatch” was an important factor in the Lateran Council’s reducing the permitted degrees of relatedness to four in 1215.
The Geography of Church Influence
Regarding the central claim that the length of time under the influence of the Western Church was critical to the rise of individualism, I note the following in Chapter 5:
There are other grounds for emphasizing the underlying ethnic component of Western individualism and egalitarianism. For instance, there were important differences between Western and Eastern Christendom, and within Western Christendom itself. Regarding the latter, at least from the early Middle Ages, the Western family pattern was confined to northwest Europe, particularly the area encompassed by the Frankish Empire, Britain, and Scandinavia, but not, as emphasized in Chapter 4, the region to the south of the Loire in what is now France, and excluding much of Europe outside the Hajnal line despite being part of the Western Christendom (e.g., southern Italy [although I accept Schulz et al.’s argument for that southern Italy was subjected to Church influence relatively late—in the eleventh century (S2.2, 9)—this is much earlier, e.g., than Sweden which, along with other Scandinavian countries, has the most individualistic family structure in Europe], Ireland, the southern Iberian peninsula, Croatia and parts of eastern Europe). Individualist family structure, which many scholars point to as critical for understanding the rise of the West, thus fails to include significant parts of Western Christendom.
One might argue that differences in family structure between Eastern and Western Europe are explainable by the later introduction of Christianity in Eastern Europe. Poland, for example, was Christianized relatively late (beginning in the tenth century) compared to the Frankish Empire (beginning with the conversion of Clovis I in 496). However, Scandinavian societies, which have the most individualist family structure in Europe (see Chapter 4), also converted quite late. For example, Denmark, the first Christian Scandinavian country, became Christianized only after the conversion of Harold Bluetooth in 972. Sweden followed much later, first establishing an archdiocese in 1264, and even then, the eradication of pagan practices and beliefs took another 150–200 years. Ethnic differences are a far more parsimonious explanation. [From Chapter 5, 222]
Several of the points in my summary of the material on family structure in Chapter 4 can also be applied to the question of the importance of Church influence with appropriate modifications (in brackets).
The central argument here is that the origins of the unique northwest European family structure lie in biological influences stemming from a combination of Indo-European peoples originating on the steppes of southeast Europe and hunter-gather peoples whose evolutionary past lies in northwest Europe itself.
The widespread practice of placing servants in households of non-relatives cannot be explained in purely economic terms as a response to medieval manorialism [or Church influence]. However, it is compatible with elaborate systems of non-kinship-based reciprocitythat have been noted in hunter-gatherer cultures in harsh environments (Chapter 3) as well as a characteristic of Proto-Indo-Europeancultures and their descendants (Chapter 2) dating back thousands of years.
Also compatible with primordialistexplanations, … historians are unable to firmly date the origins of the individualist family. The fact that customs of monogamy, late marriageand individualist inheritance patterns long preceded the early Middle Ages [and therefore Church influence] suggests that the individualist family pattern is rooted in the evolutionary history of the northwest European peoples. [This contrasts with Schulz et al.’s (p. 2) claim that the nuclear family pattern found in Western Europe was the direct result of Church policy.] …
The very different family forms in northwest versus much of southern Europe (including southern France) persisted in near proximity despite the same religion (until the Reformation) and despite manorialism [and Church influence] in both areas as a result of the Frankish conquests.
[This contrasts with Schulz et al. lumping all of France into the same category of Church influence because of its incorporation in the Frankish Empire (see their Figure 1A)—despite the very clear differences in family structure along relatively individualist (northern France) and relatively collectivist (southern France) structures. Further, Schulz et al. use proximity to a bishopric as measured in 50-year intervals from 550 AD to 1500 as their measure of Church influence. However, their Figure S2.1 shows that the relatively collectivist southern France (see Chapter 4) had at least as many bishoprics in 1000 and in 1500 as the relatively individualist northern France and many more than Scandinavia which has the most individualist family structure in Europe (see my Chapter 4). Finally, while Schulz et al. note that southern Italy was incorporated into the Western Church relatively late, thus purporting to explain their relatively intensive kinship relations, my treatment emphasizes the ethnic difference between northern and southern Italy, with Germanic peoples predominant in the north.]. …
There is a cline within northwest Europe such that the most individualist family patterns occur in Scandinavia, particularly Sweden which never underwent manorialism [and, as noted by Schulz et al. (see their Figure 1A and Figure S2.1), was exposed relatively late to Church influence.] [From Chapter 4, 165–167]
I conclude that the extent of Church influence is inadequate as an explanation of Western individualism and that an adequate account requires a consideration of the unique evolutionary history of the peoples of Western Europe.
 Jonathan F. Schulz, Duman Bahrami-Rad, Jonathan P. Beauchamp, and Joseph Henrich, “The Church, Intensive Kinship, and Global Psychological Variation,” Science 366, no. 707 (November 8, 2019): 1–12, 1.
 T. Douglas Price, “The Mesolithic of Northern Europe,” Annual Review of Anthropology 20 (1991): 211–233, 229.
 Marek Zvelebil and Paul Dolukhanov, “The Transition to Farming in Eastern and Northern Europe. Journal of World Prehistory 5 (1991): 233–278, 262–263.
 Sveinung Bang-Andersen, “Coast/Inland Relations in the Mesolithic of Southern Norway,” World Archaeology 27 (1996): 427–443, 436, 437.
 Michael L. Burton, Carmella C. Moore, John W. M. Whiting, and A. Kimball Romney, “Regions Based on Social Structure,” Current Anthropology 37 (1996): 87–123.
 Iain Mathieson et al., “Genome-Wide Patterns of Selection in 230 Ancient Europeans,” Nature 528 (2015): 499–503; see also Morton E. Allentoft et al., “Population Genomics of Bronze Age Eurasia,” Nature 522 (June 11, 2015): 167–172.
[6a] James E. Lindsay, Everyday Life in the Medieval Islamic World (Westport, CT: Greenwood, 2005), 45–46.
 Ricardo Duchesne, The Uniqueness of Western Civilization (Leiden: Brill, 2011), 438.
 David Anthony, The Horse, the Wheel, and Language: How Bronze-Age Riders from the Eurasian Steppes Shaped the Modern World (Princeton, NJ: Princeton University Press, 2007; paperback edition, 2010), 364.
 Ibid., 238.
 Kevin MacDonald, A People That Shall Dwell Alone: Judaism as a Group Evolutionary Strategy (Westport, CT: Praeger, 1994).
 “Israel Imposes Apartheid Regime on Palestinians: UN Report,” Reuters (March 152, 2017).
 Gary Forsythe, A Critical History of Early Rome: From Prehistory to the First Punic War by Prof. Gary Forsythe (Berkeley: University of California Press, 2005), 185.
 Ricardo Duchesne, The Uniqueness of Western Civilization (Leiden, the Netherlands: Brill, 2011).
 G. Miccoli, “Monks,” in Jacques LeGoff (ed.), Medieval Callings, trans. L. G. Cochrane (Chicago: University of Chicago Press, 1990): 37–74, 57.
 John T. Noonan, “Power to Choose,” Viator 4 (1973): 419–434, 430.
 See Kevin MacDonald, “Mechanisms of Sexual Egalitarianism in Western Europe,” Ethology and Sociobiology 11 (1990):195–238.
 Kevin MacDonald, “The Establishment and Maintenance of Socially Imposed Monogamy in Western Europe,” Politics and the Life Sciences 14 (1995): 3–23; Kevin MacDonald, “Focusing on the Group: Further Issues Related to Western Monogamy,” Politics and the Life Sciences 14 (1995): 38–46.
 Walter Ullman, The Growth of Papal Government in the Middle Ages: A Study in the Ideological Relation of Clerical to Lay Power, 3rd ed. (London: Methuen, 1970), 1.
 Schulz et al., “Prevalence of Cousin Marriage,” Supplementary material S1.2, 6–7.
 Amy Goldberg et al., “Ancient X chromosomes Reveal Contrasting Sex Bias in Neolithic and Bronze Age Eurasian migrations,” Proceedings of the National Academy of Science 114, no. 10 (March 7, 2017): 2657–62.
 Peter Frost, “European Hair and Eye Color: A Case of Frequency-Dependent Sexual Selection?,” Evolution and Human Behavior 27 (2006): 85–103.
 Frank Salter, “Carrier Females and Sender Males: An Evolutionary Hypothesis Linking Female Attractiveness, Family Resemblance, and Paternity Confidence,” Ethology and Sociobiology 17, no. 4 (1996): 211–220.
 Brent D. Shaw and Richard P. Saller, “Close-Kin Marriage in Roman Society?,” Man (New Series) 19, no. 3 (September, 1984): 432–444, 432.
 Ibid., 438–439.
 C. B. Bouchard, “Consanguinity and Noble Marriages in the Tenth and Eleventh Century,” Speculum 56 (1981): 268–287.
 John Goody, The Development of the Family and Marriage in Europe (Cambridge, U.K.: Cambridge University Press, 1983), 145; one effect of this policy, emphasized by Goody, was that families were often left without direct heirs and left their property to the Church.
 Karl E. Leyser, Rule and Conflict in Early Medieval Society (London: Edward Arnold, Ltd., 1979), 50.
 Bouchard, “Consanguinity and Noble Marriages in the Tenth and Eleventh Century.”
 Elizabeth Archibald, Incest in the Medieval Imagination (New York: Oxford University Press, 2001), 37.
 Ibid., 38.
 Ibid., 41.
 Bouchard, “Consanguinity and Noble Marriages in the Tenth and Eleventh Century,” 269.
 See Ch. 4; see also Michael Mitterauer, Why Europe? The Medieval Origins of Its Special Path, trans. Gerald Chapple (Chicago: University of Chicago Press, 2010; orig. German edition, 2003), 62.
 “Harold Bluetooth,” Catholic Encyclopedia.
 “Christianization of Scandinavia,” Wikipedia.https://en.wikipedia.org/wiki/Christianization_of_Scandinavia
 See Ch. 4; see also Mary S. Hartman, The Household and Making of History: A Subversive View of the Western Past (Cambridge, U.K.: Cambridge University Press, 2004); Michael Mitterauer, Why Europe? The Medieval Origins of Its Special Path, trans. Gerald Chapple (Chicago: University of Chicago Press, 2010; orig. German edition, 2003), 62.