In contemporary sociological and demographic research, modernity is typically understood to refer to the widespread cultural changes that got under way during the second half of the eighteenth century as a result of the Enlightenment and the Industrial Revolution (Anderson ). Economic growth is viewed as a core element of those changes, but it is unlikely that the processes associated with modernity could have occurred without the unprecedented organizational reach that governments acquired at that time (Mouzelis ). In the century or so thereafter, a number of Western nations set out on a path of modernization, and in more recent times, its effects have been observed in many non‐Western nations with markedly diverse cultural backgrounds.

While the term modernity is associated with growth in economic development, it also embraces a number of closely associated cultural phenomena that appear as the process of modernization progresses. The array of such phenomena is extensive and includes, among many other features, industrialization and capitalism, urbanization, democratization, gender egalitarianism, growth in scientific knowledge and technology, secularization, individualism, and a belief in progress (Berman ; Giddens ; Everdell ; Wagner ; Santos, Varnum, and Grossman ). Indeed, one might reasonably hold that modernity is such a pervasive shaper of Western societies, and in more recent times of other non‐Western societies, that those of us who have grown up within its orbit are hard pressed to be able to take its measure. It flavors our thought whichever way we turn.

Still, that has not dampened efforts to understand the nature of the dynamics that triggered and sustain the wide and all‐embracing range of characteristics expressive of modernity. What are its key features? Can we specify its driving forces? To what extent can it be analyzed quantitatively? Two broad types of explanation dominate the field (Richerson and Boyd ; Newson and Richerson ). One, sometimes termed environmental, holds that individuals within populations adjust their behavior, through the use of reason‐ and evidence‐based skills, especially cost‐benefit analysis, in response to changes to social, economic, and physical environments; modernity, in this view, is primarily the result of such changes achieved through individual decision making. The alternative type of theory, evolutionary, places emphasis on long‐term, cross‐generational and within‐generational social learning processes of cultural transmission, which are viewed as the primary drivers of cultural change, and thus of modernity. The distinction broadly parallels that proposed by psychologists in what are called dual‐process theories (rapid, intuitive, and emotion guided versus slower, conscious, rational cognitive processes; Evans, ; Haidt ). The label evolutionary derives from the fact that those putting forward this kind of theory draw their conceptual models from work in the field of evolutionary biology. Its proponents are commonly referred to, and refer to themselves, as cultural evolutionary theorists (Cavalli‐Sforza and Feldman ; Boyd and Richerson ). In sum, then, the former type of explanation looks to relatively immediate, reason‐based factors behind cultural change, whereas the latter, by contrast, considers more influential the longer term, culture‐wide social processes they identify (Newson and Richerson ). Colleran () examines the overlap between these two approaches).

Here, I will draw primarily on the latter, evolutionary approach to sketch an account of the pathway toward modernity. I will be relying largely but not exclusively on a theory called the kin influence hypothesis, proposed by Lesley Newson and Peter Richerson, which sees the emergence of modernity as arising from the loss in relative importance of cultural information transmitted by family/kinship groups (Newson and Richerson ; Newson, Richerson, and Boyd ). More specifically, this hypothesis argues that, with the advent of economic development, there is typically a reduction in total fertility rate. (Total fertility rate—hereafter fertility rate or simply fertility—is, roughly, a measure of how many children a woman might be expected to bear during her childbearing years.) This reduction occurs following the profound change in social relationships, for example rural to urban migration, and has the effect of both restricting people's exposure to the pronatalist attitudes (i.e., attitudes which encourage couples to have offspring) characteristic of interaction among kinship groups, and augmenting contact with neutral or antinatalist attitudes that are associated with nonkin relationships. On the basis of what are fairly small observed differences in the relative influence of pronatalist and antinatalist or neutral views over generations, according to this hypothesis the major contours of modernity take form (Newson et al. ; Newson, Richerson, and Boyd ). The theoretical sketch I wish to offer, while based in the work of Newson and colleagues, aims to extend it by incorporating further relevant evidence relating to the process of secularization. 

In considering the matter theologically, my primary interest in a cultural evolutionary approach to modernity is what it might have to contribute to a faith perspective on the decline in religious belief and practice in Western nations. Newson and Richerson themselves have related their kin influence hypothesis to religious phenomena understood in scientific terms (Richerson and Newson ; Newson and Richerson ) and my aim here is to take account of that work. A specifically theological perspective on these matters has relevance for those who seek to understand the dynamics and contexts that have a bearing on the faith of believers. There have been a number of contributions to more general theological reflection on modernity as a sociological phenomenon, and on secularization as a significant aspect of it (e.g., Cox ; Hill ; Habermas and Ratzinger ; Taylor ), but to date no publications appear to have taken account of the more recent evolutionary approach. In this, possibly first such attempt at coming to terms with its understanding of modernity, I will highlight, in a few brief concluding reflections, some of its possible implications for Christian faith.

CULTURAL EVOLUTION AND MODERNITY

The kin influence hypothesis of Newson, Richerson, and their colleagues is proposed as a partial explanation for the development of modernity. They begin their account by pointing to the line of work initiated by Émile Durkheim that argues that the growth and diffusion of wealth leads to dramatic changes in the way people relate to each other (Durkheim [1893] ; Batson ; but see also Schulz et al. , who propose causal factors working in the reverse direction). They then note that prior to an historic upturn in industrialization and economic growth, the major context for social interaction is the family and its extended kinship circle. As is typically observed, the advent of industrial development and its concomitant economic growth necessitate the emergence of modes of cooperation that are not kin‐based, and frequently involve strangers who come together for commercial or other restricted economic and social reasons. Of course, widespread population movements from rural to urban environments have played a large part in this transition from essentially kin‐based to non–kin‐based social interaction, but other processes such as the rise of education, have also been operative (Colleran et al. ).

The specifics of Newson and Richerson's hypothesis begin to appear in their work relating a nation's economic development to its fertility rate. They have observed that, in a quite consistent manner, the latter variable begins to decline in the period beginning soon after a rise in national wealth (Zelinsky ; Newson and Richerson ). Of particular interest is their observation that, whatever happens at the economic level, once the fertility rate begins its decline, it proceeds on a downward path over a period of decades until it reaches a level roughly at, or more likely below, the lifetime replacement rate of approximately 2.1 children per woman.

Figure  shows the current fertility rate for a large sample of nations and relates each figure to the year when that rate began to decline. Those points to the left of about the 1960–70 period represent nations that have largely reached a fertility rate at or below replacement level. Nations to the right of that period are those whose fertility rate began to decline more recently and are now, for the large majority of them at least, still in the process of moving toward replacement level. The former are nations where industrialization occurred early, while the latter are typically developing nations.

Year Fertility Began to Decline versus Total Fertility Rate in 2015 (Data for 158 Countries for Which Fertility Rates Have Begun to Decline).

Data sources: Newson and Richerson ; World Bank .

The primary reason for this downward trend in fertility rate, according to Newson and Richerson, is that, with economic development, the ratio of kin to nonkin influences on a given individual begins to decline. Increasingly, the exposure to and impact of kinship diminishes, while there is a correlative growth in nonkin influences. According to the authors, this process is largely the result of changes in a specific culturally transmitted tendency. They have provided suggestive evidence that there is a small but robust propensity within social interactions between kin for the bearing of children to be valued and promoted, something not observed in communications among nonkin. What they propose is that this dynamic whereby there is an encouragement to bear children within kinship circles, over a period of many generations, has the effect of sustaining the fertility rate, such that when the process is compromised, there is a consequent loss in the perceived value of bearing children (for the effect of context, see Sear and Coall ). What comes in its train is a reduction in the fertility rate, and thereafter, all kinds of changes that are associated with modernity. Among these are growth in education and general intelligence, bureaucratization, individualism, the increasing instrumentalization of relationships, reduction in corruption, changing views about authority, and, not least, secularization. A key implication that Newson and Richerson draw from this is that the extent to which the process of modernization has progressed depends largely on the time in history when a nation's fertility began to decline (Newson and Richerson ). Earlier tipping points are linked to more advanced modernization, whereas more recent declines in fertility are associated with less progress along that pathway.

Thus, the kin influence hypothesis is that the growth in a nation's economy prompts a decline in fertility rate and this, as a factor largely independent of economic development, has flow‐on effects that together exercise a profound shaping of what we know as modernity. There are two questions associated with this idea that must be distinguished: (a) how central is fertility reduction to the broader process of modernization? and (b) is cultural transmission of pronatal attitudes within kinship circles the primary means by which chronic fertility decline occurs? Let us consider them in turn.

SECULARIZATION AND FERTILITY RATES

Analyses of a number of data sets point to a loss of religious commitment among nations as they advance toward higher levels of economic development (Crockett and Voas ; Norris and Inglehart ). Among the best available data are those produced by the large‐scale Word Values Survey, which has tracked beliefs and values internationally since 1981. As some leading researchers in the field have observed, “the publics of virtually all advanced industrialized societies have been moving toward a more secular orientation” (Norris and Inglehart , 24–25). Such findings support the so‐called secularization thesis, the idea that movements in the direction of a loss of influence of religious beliefs and institutions occur as a consequence of modernization and rationalization.

Some have noted a number of difficulties with the thesis, not least of which is that it seems to apply reasonably well to Western nations with Christian cultural histories, but less so to others. For example, according to data from the World Values Survey (Wave 6), non‐Western nations with Muslim majorities that have experienced economic growth have not witnessed a serious downturn in indicators of the importance of religion in the lives of their citizens. Similarly, in recent years, several former Communist states aligned with the Soviet Union have experienced increases in religious identification even in the face of rapid economic development. Furthermore, although all Western nations have dominant Christian traditions, it seems that some strongly Catholic countries, for example, Poland, Italy, Ireland, and Malta, have observed a slower or more delayed falling away of religious faith than have those with traditionally Protestant or Anglican majorities, for example, Scandinavian nations, England, Canada, Australia, and New Zealand (for relevant data, see World Values Survey website, Wave 6 2008–14). The commonly noted exception to this, the United States, has in recent years shown a quite rapid decline in religious faith, although why it has taken so long to occur is not clear. Overall, then, the idea that secularization inevitably follows industrialization can no longer be sustained. However, within vulnerable cultures and given a sufficiently advanced stage of development, the thesis is still a live option among sociologists, although what the primary drivers and boundary conditions of the process of secularization are still a matter of vigorous discussion (Bruce ).

What might be some of the key causal factors? Early social scientists, such as Durkheim and Max Weber, shaped their explanatory narratives in terms of Enlightenment themes. From this perspective, one could understand what was happening as a matter of society discarding religious beliefs and superstition to replace these with a scientific and rational outlook (Weber [1920] ; Pickering ; Weber [1920] ). This overtly ideological orientation has largely subsided, although there are signs that a similar stance still operates in those explanations that see secularization in terms of a process of increasing freedom from the constraints of the past. Such factors as reliable income, technological innovation, and the free flow of information lead to the questioning of religious beliefs, it is argued, and thus open the way to a more secular and science‐based understanding of existence (Bruce ; against this, see Martin ).

Among the most widely discussed theories of secularization is that developed by Ronald Inglehart, Pippa Norris, and colleagues (e.g., Norris and Inglehart ). They argue that religion is primarily to be understood, at least in sociological terms, as a source of security for people who live in otherwise insecure societies. With increased national wealth, the possibility arises of a general improvement in security that comes with universal health care, a developed education sector, and an effective system of law and order. They point to Scandinavian and other Northern European nations as examples of countries that provide their citizens with a range of “safety nets” and, at the same time, have some of the lowest levels of religious faith and practice in the world. The seemingly anomalous case of the United States, which has retained high levels of religious faith while also being economically advanced, fits this theory, because, as Norris and Inglehart argue, the limited extent of health care cover and social security safety nets more generally in that nation are associated with an elevated insecurity. This has, in turn, helped to sustain religious faith.

According to Newsom and Richerson, however, while one can acknowledge a correlation between degree of secularization and level of security, this does not mean that there is a direct causal link between the two. They note that, in many nations, along with increasing economic development comes, at least in the period immediately after the increase, not a decline but a growth in religious practice. They suggest that “the influence of religious organizations tends to rise after the start of economic development and then begins to decline as modernization proceeds” (Newson and Richerson , 206). Moreover, and crucially, there is such a cross‐national variability in the development of secularization that one must look for other factors to help explain the phenomenon. Finally, when we consider that the Norris and Inglehart hypothesis applies primarily to nations with particular cultural and religious backgrounds, it becomes clear that there is much room for further elaboration and, perhaps, correction, of this theoretical framework.

As a test of their own position that fertility rate (as a proxy for kin versus nonkin influence) is a leading factor in the explanation of secularization, Newson and Richerson related cross‐national survey responses to a number of questions measuring moral and religious beliefs against both the variable YFBD and that of per capita GDP (). For 16 of the 18 questions, the correlation with the YFBD was stronger, often by a large amount, than with the economic variable. Given the large sample sizes, the wide range of nations sampled, and the fact that the majority of correlations were within the range 0.6–0.8, one might reasonably hypothesize that (a) “evolutionary” processes are likely to play a dominant role (since relationship with YBFD points to an “evolutionary” process) and (b) that there is a good chance that long‐term social learning, even more so than factors closely linked to the extent of a nation's economic development, serves as a significant element in the causal explanation of secularizing processes.

But what sort of account might be constructed to make sense of this connection? I would like to offer some brief comments that draw on the historical relationship between the values and norms traditionally found within families, and those especially within Catholic forms of the Christian faith.

IMPLICATIONS FOR CHRISTIAN FAITH

Reflection on the phenomenon of modernity from the point of view of Western Christian faith has been extensive, not least because of the steady and at times dramatic decline in religious faith over many decades, and in some cases, centuries. It is, therefore, to be expected that the many etiological narratives that seek to identify the key factors in the rise of secularism should have emerged. This is indeed the case (e.g., Gilson ; MacIntyre ; Dupré ; Milbank ; Miner ). The work I have considered here suggests that the forces pushing in the direction of modernity and secularization are quite complex, and that, over and above rationales of a philosophical or theological nature, cultural evolutionary processes must be more seriously considered. This complexity arises from the fact that such processes operate as a kind of intermediate level of analysis between rational thought, revealed beliefs, and the vagaries of history, on the one hand, and strictly environmental conditions on the other. Although cultural evolutionary processes give expression to the biological exigencies of survival and reproduction, they show themselves in the form of beliefs, practices, and culture‐wide assumptions (e.g., that a mother should wean late, or that marriage is a lifelong partnership). And, because they take that form, they are amenable to influence by, for example, convictions of faith, which themselves cannot be reduced to epiphenomena of biological and cultural processes, although they are shaped to some extent by these. Rodney Stark (, 105–07, 73–94) offers evidence for the changes wrought by Christian beliefs on ancient Roman assumptions about age of marriage for young women, and on the best ways to respond to disease epidemics. Faith‐related influences of this nature, he argues, were differentially adaptive, resulting in discernibly better outcomes, and help to explain the rise of Christianity during its early centuries. In sum, then, one might usefully draw an analogy between environmental explanations of human behavior based on rational cost‐benefit analysis and the theological tradition that has favored intellectualist conceptions of modernity and secularity. While this mode of thinking certainly has validity, I have argued that the existence of potentially more powerful evolutionary models for understanding these cultural phenomena points to the need to complement such intellectualism by taking fuller account of other‐than‐rational processes shaping religious belief and practice. To do so is to open the way to a deeper and truer theology of faith and culture.

The evidence reviewed in this article points to the power of inbuilt biases (kin, prestige, and conformity) and social learning among humans as key elements in the diffusion of religious beliefs and practices. Thus, we tend to follow others’ thinking more than we realize, and not just any others’ but particular groups within our social/informational world. How that world is shaped, whether primarily by kinship/religious interactions that are able to mutually support each other, or by engagement with nonkin groups, exposure to high‐status models of a “neutral” religious posture, or by living with the security of state‐generated “safety nets,” has a profound effect on the way Christian belief figures in our lives. A theological treatment of the processes of modernity needs to take these matters into account.

I would also remark that modernity's effects on human reproductive practices, at least on current projections, are shaping demographic trends that are probably not sustainable in the long term. Although demographic predictions, including those of the United Nations Population Division (), suggest that the global population will, on roughly its current trajectory continue to increase for the next century, its rate of increase is even now in decline, and some projections are that eventually the world's population will commence a long decline. Added to this, the constellation of beliefs and attitudes that low fertility rates bring with them appears to be of a kind that weakens, in the long term, the “glue” that is necessary for a large‐scale society to sustain itself (Henrich ). The preferences for instrumentalist models of relationship and for the ordering of social bonds through the use of bureaucratic norms provide a rather “thin” or fragile foundation for shock‐resistant social structures. Relevant here is the notion proposed by some, that an important social function of religious belief is to provide the cohesive force necessary for large‐scale societies to exist (e.g., Norenzayan et al. ).

Whether this is the case or not, reduced fertility among believers, of necessity, means a steady decline in the Western Christian faith: fewer clergy, greying and thinning congregations, and a pervasive loss of institutional energy. The outcome, in short, will be that there is not much material for the grace of God to work with. This prompts a reflection on the theological conviction that “grace purifies, confirms and builds upon nature” (see Catechism of the Catholic Church , §§ 286, 865, 1152, 1203, 1644). The two key “imperatives” in the continuing existence of species are survival and reproduction. Unlike rationality, freedom, or relationality—which are commonly viewed as core features of humanity, viewed theologically—survival and reproduction, as two constants in human existence, are not distinctively descriptive of our species, but they are certainly part of our nature as animals. For this reason, it makes sense that they should be considered when determining what “nature” it is exactly that is purified, confirmed, and built on by grace. At least in the long run, a failure of reproduction is just as much a hindrance to grace as is, say, the serious brain damage caused by long‐term drug abuse.

In view of the cultural evolutionary approach I have presented here, the way forward for Christian believers in the face of the process of modernity, while not obvious, at least points in some directions that have not been prominent in past treatments of the matter. Certainly, there is raised the interesting possibility that a Christian response might, at least in the first instance, need to focus on encouraging the birth of offspring among believers and on the nurture of families and wider kinship circles. Within this framework, the orientation of church life would need to be turned toward the shaping of family and kinship ideals in ways that more and more reflect the Christian faith and the exigencies of the present time. Perhaps one of the biggest hurdles in achieving this would be the construction of a narrative, especially for young women, that takes account of both individual and maternal/spousal vocations to which most of them will be called. Less obvious, however, is a similar imperative for young men to better balance their own individual and paternal/spousal callings.

For theologians, what has been offered, at least by implication, is a challenge to rebalance a traditionally dominant focus on the world of ideas so as to incorporate a deeper consideration of the cultural conditions in which the faith is lived out. Ideas, although important and life‐shaping in their own right, are also and to a significant degree the visible cultural elements whose less apparent vectors are cultural evolutionary processes involving such historical phenomena as economic growth and fertility rates. For the sake of the faith, intellectual humility urges us to take these matters into consideration in our theologizing.

CONCLUSION

The approach of cultural evolutionary theory represents a relatively new mode of understanding larger scale social, demographic, and economic dynamics operating over time spans measured in decades and centuries. The work of Newson, Richerson, and their colleagues draws on this approach in an attempt to shed light on the rise of modernity, and on secularization as one of its key features. Their central finding is that a key trigger among the many processes that bring about the emergence of modernity is the decline in fertility rate and its stabilization at or, more commonly below, replacement level. What then develops is the predominance of nonkin over kin influences and flow‐on effects on social relations, cultural norms, economic development, and education. Following their lead, I have proposed further mechanisms by which the connections between fertility decline, modernity, and especially secularization can be understood. More specifically, I have put forward the idea that a significant factor in bringing about loss of religious belief and practice in Western nations is the emergence of a number of cultural values and norms antithetical to those that have historically been held by both families and Christian denominations, and that have been mutually sustaining for those institutions.

I have drawn two main implications from this understanding of modernity and secularization: first, that, in facing the corrosive effects of modernity with its impact on faith, the commonly accepted notion that Christian believers are engaged in what is essentially a battle of ideas needs to be called into question as at least an incomplete and possibly a serious misreading of reality; second, that the failure of believers to heed the divine command to “be fruitful and multiply” (Genesis 1:28 NRSV) is perhaps one of the core issues that Western Christian churches need to address if they are to extricate themselves from the seemingly inexorable decline they are currently experiencing.

What I have offered here is, of course, only an initial attempt to come to terms with the cultural evolutionary perspective and, in particular, the work of Newson, Richerson, and others as it relates to modernity and secularization. It potentially offers a powerful theoretical framework for understanding such broad cultural changes, and further efforts are needed to test it and to refine its findings. For Christian faith, moreover, it holds out the possibility of further enriching the links between a scientific understanding of nature and history, on the one hand, and the work of grace, on the other.