Human self-selection as a mechanism of human societal evolution: A critique of the cultural selection argument

Survival needs and natural selection

Biological evolution is a process of ‘descent with modification’ (Darwin, 1859). More specifically, this process is driven by natural selection involving genetic adaptation of organisms to their environment for survival and reproductive success (Dawkins, 1976; Lewontin, 1983). The following concepts are crucial for understanding this evolutionary process: population, environment, selection pressure, reproductive fitness, adaptation and selection. The evolution of species takes place at the level of the population, that is, the aggregation of changes in the individual organisms of a species. To a given population of individual organisms, the environment includes everything that is exogenous to the population but influential to the existence of the individual organisms; relative to a given individual organism, the environment also includes other conspecifics in the population.

Selection pressure refers to the forces that compel organisms to interact with the environment to survive and reproduce. This pressure comes internally as well as externally. The internal selection pressure consists of a set of innate biological needs that must be satisfied for an organism to live and procreate, for example, the need for food, sleep and sex. The fulfilment of those needs gives the organism pleasure and failure to do so leads to suffering and death. The external selection pressure consists of the threat in the environment that makes it difficult for the organism to meet its innate needs, and such threats include extreme weather, food shortage, attacks from predators and the spread of pathogens. The combination of innate survival needs and external environmental threats constitutes the powerful selection pressure that drives an organism to look for food, compete for mates and, consequently, produce offspring.

Reproductive fitness is a measure of an organism’s success in responding to the selection pressure. If the organism fails to meet its internal survival needs in fighting against the external environmental threats, the organism will die prematurely and leave no progenies; otherwise, the organism will survive long enough to have descendants. An organism’s success in responding to the selection pressure can therefore be measured in terms of the degree of its reproductive fitness: the more descendants it produces, the more successful it is. However, a broader measure of reproductive fitness is an organism’s inclusive fitness, which is the survival of the total number of an organism’s genetic relatives (Hamilton, 1964). An organism can promote its inclusive fitness by helping its relatives produce more offspring, thereby increasing the representation of their genotypes in the population.

Adaptation refers to the change in the phenotypic characteristics of an organism that enhances its reproductive fitness in the environment. An organism’s phenotypic characteristics are determined by the interaction between the inherited genotype and its environment. The inherited genotype provides a set of genetic instructions for the development of the physical form and the behavioural patterns that proved adaptive in the ancestral environment as well as a learning capacity that helps the organism adapt to novel situations. While the capability for learning varies among species, and among individuals within a species, the ‘Principle of Least Effort’ (Zipf, 1949) appears to operate in the calculus of all organisms. In response to the specific selection pressures they encounter, different species exhibit varying degrees of phenotypic plasticity that ‘permits organisms to mold their form [and behavior] to prevailing circumstances during ontogeny’ (Gould & Lewontin, 1979, p. 593).

Natural selection is the process of passing on the genes of the best-adapted individual organisms to their offspring through biological reproduction. Individuals with adaptive phenotypic characteristics are more likely to survive and reproduce than those without such characteristics, and, as a consequence, the allete frequencies in the gene pool of a population will change over time, favouring the genotypes that maximize the reproductive fitness of the members of the population. Genetic variations in a population are caused by multiple factors, including mutation, gene flow (recombination) and genetic drift, but natural selection is the primary mechanism that drives the evolution of biological species in nature. For that reason, natural evolution has sometimes been referred to as the genotypic adaptation of organisms to their respective environments for survival and reproductive success through the process of natural selection.

The cultural selection argument

Natural selection has also been used to explain the evolution of the societies of individual organisms, including humans. In sociobiology, society is defined as ‘a group of individuals belonging to the same species and organized in a cooperative manner’ (Wilson, 2000 [1975], p. 8). Depending on the degree to which individual organisms rely on the cooperation with their conspecific members for survival and reproductive success, varying levels of ‘societality’ – for the lack of a better word – can be distinguished. It ranges from situational collaboration among males for meat hunting in chimpanzee communities (Boesch, 2003), to collective living and hunting in wolf packs (Mech, 2003 [1970]), and to the division of labour among all members for all aspects of life in ant colonies (Holldobler & Wilson, 2009). As level of societality rises, the interdependency of conspecific members increases. In the sense that collaboration with conspecifics helps individual organisms improve their chance of survival and reproductive success, ‘societies are adaptive mechanisms that mediate relations between a population and its environment’ (Lenski, 2005, p. 60).

Societality must be differentiated from sociality. Sociality is a psychological attribute that pertains to the emotional relatedness of individual conspecifics, whereas societality is a structural property that reflects the interdependence of different functional units of a society. Societal parameters include, among other things, mode of food acquisition, mating system, dominance structure, population size and methods of territorial defence (Meyer, 2004). There is no necessary correlation between levels of societality and sociality. For example, ant colonies have high societality but low sociality, and chimpanzee communities have low societality but high sociality. Different combinations of the levels of societality and sociality give rise to a variety of animal societies with different forms and functions, all of which are phenotypic adaptations of social organisms to their respective environments.

There is a genotypic foundation for the societies of individual organisms. All social organisms are genetically endowed with a social capacity that varies with species. This genetic endowment provides social organisms with the need as well as the capability for collaboration with conspecifics. Capacities for emotional bonding, self-awareness, social learning and linguistic communication are inherited genotypes that are necessary for the formation of different types of societies. However, genes alone are incapable of accounting for the diversity of societies in nature. In interacting with their environments, organisms also develop different forms of culture through social learning to enhance their reproductive fitness (Bonner, 1980). Culture is anything that is created by organisms through learning from one another, as opposed to through genetic inheritance. Experience, skill and behaviour acquired from other social members are examples of culture, which can be found in many societies of organisms (Avital & Jablonka, 2000). However, unlike genetic variants that can be passed on to offspring through reproduction, cultural variants are not biologically inheritable. Moreover, in all non-human animal societies, the change of cultural variants over time is accompanied by little cumulation (Laland & Hoppitt, 2003).

It is a different case with human societies. Humans are endowed with high intelligence and a superb capability for learning, in addition to reflective self-awareness and the ability to use a syntactic language. These genotypic attributes make human individuals unparalleled social learners and super cultural innovators (Henrich, 2016; Laland et al., 2000). In striking contrast to the culture in non-human animal societies, culture in human society is not only inheritable through teaching and learning but also highly cumulative. Cultural variants abound in human society, and they include knowledge, technology, material artefacts, as well as traditions and institutional rules that regulate social and societal interactions. Because so much of human societal functioning relies on the development and use of culture, human society can be seen as a cultural entity (Henrich, 2016).

The ‘cultural selection’ argument is an effort to amend the natural selection theory by incorporating cultural transmission as a second mode of inheritance in human evolution (Boyd & Richerson, 1985; Cavalli-Sforza & Feldman, 1981; Tooby & Cosmides, 1989). Parallel to the inheritance of adaptive genotypes through biological reproduction in genetic adaptation, the transmission of adaptive cultural variants – mostly ‘memetic information’ (Dawkins, 1976) such as ideas and beliefs – takes place through social learning. But, unlike the inheritance of genotypes, which is essentially a non-purposeful biological process, cultural transmission is a part of human intentional action, as ‘guided variation’, ‘biased transmission’ and other forces of cultural change are influenced by human intentionality and decision-making (Boyd & Richerson, 1985; Henrich, 2012). Depending on the type of fitness cultural transmission is believed to maximize, two different versions of the cultural selection argument have been put forward: (1) cultural transmission as cultural adaptation and (2) cultural transmission as cultural selection. Differences between these two versions have been largely neglected in the literature, although they are in fact critically important.

The cultural-transmission-as-adaptation argument regards cultural transmission as a second channel of information inheritance under the influence of natural selection. According to this argument, natural selection acts on both genes and culture in driving human societal evolution (Boyd & Richerson, 1985; Lumsden & Wilson, 1981). By retaining the adaptive variants of genes through biological reproduction and the adaptive variants of culture through social learning and teaching, natural selection seeks to maximize the reproductive fitness of the human population. This argument can be described as a ‘dual inheritance’ (genetic and cultural inheritance) model with a ‘single fitness principle’ (reproductive fitness), which treats genetic and cultural transmissions as different modes of human adaptation to selection pressures from the environment. Cultural transmission differs from its genetic counterpart in that genetic variants are transmitted through biological reproduction across generations (i.e. Darwinian inheritance), whereas cultural variants are transmitted through social learning within a generation (i.e. Lamarckian inheritance) as well as across generations. Nonetheless, the adaptiveness of genetic and cultural variants is assessed using the same fitness criterion – reproductive success, for ‘[t]his is the precise meaning of fitness, and in fact the only meaning of fitness. In evolutionary terms, fitness cannot be measured or assessed in any other way’ (Sanderson, 2014, p. 4). Given that genetic and cultural transmissions ‘both instantiate the same underlying process that gives rise to biological and cultural adaptation: natural selection’ (Claidiere et al., 2018, p. 192), it would be more accurate to call genetic and cultural transmissions ‘modes of adaptation’, rather than ‘modes of selection’ (Blute, 2010).

The cultural-transmission-as-selection argument, on the other hand, regards cultural transmission not as a part of, but as an alternative to, natural selection. As a separate mode of selection driving human societal evolution, cultural transmission seeks to promote the fitness of its own, that is, ‘cultural fitness’, which is different from the fitness that natural selection seeks to maximize. This is, therefore, a dual selection (natural and cultural selection) model with double fitness principles, one for each mode of selection. However, proponents of this argument have been unable to reach a consensus on what constitutes the fitness criterion for cultural selection. There have been two approaches to the specification of cultural fitness. The first approach borrows the concept of ‘reproductive success’ from the natural selection theory and applies it to cultural selection. For example, Durham (1991, p. 194) suggests that cultural fitness be measured in terms of the ‘replicative success’ of memetic transmission, namely, the rate of the spread and use of the promoted ideas, values and beliefs within a human population. The wider the transmission, the more adaptive the memetic variants are. Focusing on the construction of rule systems in human society, Burns and Dietz (1992, p. 269) define cultural fitness as the prevalence of the established cultural practice, which is associated with ‘the extent that a population adhering to the rules for generating it’. The longer the adherence lasts, the more adaptive the practice is. Turner and Maryanski (2015, p. 95) argue that ‘the only definition of fitness for a sociocultural system would be either the length of time that it exists in its environment or its ability to persist in a variety of environments’. They add that ‘sociocultural phenotypes often remain fit by deliberately changing their structures and cultures’ to sustain themselves. So, the longer a social structure can persist, the more adaptive the social system is. Cultural selection is therefore a mechanism that seeks to maximize the ‘replicative success’ of a cultural variant, rather than the reproductive fitness of a human population.

A major weakness of this approach is that it equates cultural fitness with the prevalence or durability of cultural variants without specifying what makes a cultural variant prevalent or durable. In natural selection, reproductive fitness does not need further explanation because survival and procreation are the ultimate goals of biological adaptation. In the case of cultural selection, however, it is legitimate and necessary to ask about the functionality of culture – what is culture for? If it is for something other than the maximization of survival and reproductive success, that ‘something’ must be explicated. For instance, it is important to know why some cultural variants persist for a long time while others vanish quickly. To say that a cultural practice is adaptive because it lasts, or it will last if a cultural practice is adaptive, simply fails to address the question.

The second approach aims to fix this problem. Lenski (2005, p. 69) maintains that underlying the competition for reproductive success, there is a ‘strive’ within organisms to ‘maximize pleasurable experiences and minimize painful and unpleasant ones’. In the cultural realm, this strive gives rise to the ‘economizing principle’ (p. 73) for assessing various social activities. Harris (1979, p. 138) believes that the mover of human history ‘lies in the struggle to maintain and enhance differential political-economic power and wealth, not in the struggle to achieve reproductive success’. Boyd and Richerson (1985, p. 10) acknowledge that economic wealth, political power and social status have become measures of cultural fitness in modern societies: ‘prestigious, powerful, or wealthy individuals are often attractive models, and we imitate their style of dress, their pattern of speech, and a variety of other traits’. However, they point out that the strive for such cultural fitness is not always in line with the strive for reproductive success as certain cultural activities may depart from those that would maximize genetic fitness. In contemporary Western societies, for example, the excessive pursuit of wealth, power and social status is believed to have led to an overall decline in fertility. While some scholars regard this decline as a sign of the failure of modern culture to maximize reproductive fitness (Vining, 1986), others argue that there still remains a positive association between cultural success and reproductive fitness, particularly for men, in developed countries (Hopcroft, 2021; Schneider, 2011).

Although the second approach has made headway in the specification of cultural fitness, a number of issues remain to be solved. Wealth, power and status are singled out as possible measures of cultural fitness, but there is still a lack of a general categorization of cultural fitness, equivalent to ‘reproductive fitness’ in natural selection. Also, to gain a deeper understanding of this new type of fitness, it is necessary to identify the underlying selection pressure that compels humans to pursue cultural fitness. If innate survival needs are the internal force that drives the competition among organisms for reproductive fitness, what is the internal force that drives human competition for cultural fitness? Relatedly, the concept of ‘cultural selection’ should be reconsidered. In natural selection, adaptive genetic variants are selected for by nature, or the natural environment, to be more specific. In cultural selection, cultural variants are not culturally selected, but rather socially selected, that is, ‘people, not “nature,” do most of the selecting’ (Durham, 1991, p. 198). For this reason, ‘human self-selection’ seems to be a more appropriate categorization of this new mode of selection. Finally, while it is generally agreed that natural selection applies to human societal evolution prior to the Neolithic or Agricultural Revolution, there is no consensus on why natural selection does not work well in the aftermath of the Neolithic Revolution, and the conditions under which the transition from natural selection to the new mode of selection takes place. The following section seeks to answer these questions.

Thrival needs and human self-selection

The idea that a new fitness criterion comes into play when human societal evolution moves beyond the threshold of survival and reproductive success has been around for some time. Childe (2003 [1936], p. 237, for example, states that adaptive cultural practices should enable humans to ‘live, prosper, and multiply’. By adding ‘prosper’ to the list of the fitness criterion for human evolution, Childe implies that, not satisfied with mere survival and reproductive success, humans will pursue prosperous living if conditions permit. Compared to their predecessors living in prehistoric times, writes Harari (2011, p. 93), people enjoy ‘affluence and security’ in today’s ‘prosperous societies’. ‘Prosperity’ is also used as an overarching concept in Burns and Dietz’s (1992) description of the type of fitness that human rule systems seek to maximize: adaptive rule variants will make those who adopt them ‘prosper, becoming wealthier, more prestigious, more powerful, more reproductively successful (either in the biological or cultural sense). In this case, there will be a tendency to adopt the more efficient rules’ (p. 266). Subsuming the fitness criterion for natural selection, which is reproductive success, the fitness criterion for the new mode of selection also includes wealth, power and prestige, or WPP, which, for the lack of a better term, can be categorized as ‘prosperous living’. It therefore follows that human societal evolution is driven by two distinct modes of selection, each with its own kind of fitness: natural selection for reproductive success and human self-selection for prosperous living.

If natural selection for reproductive success is driven by the biological survival needs of the human organism, what drives humans to pursue wealth, power and prestige? Do humans have innate needs for prosperous living? Non-human animals are generally satisfied once their biological needs are met, although there is some degree of plasticity ranging from the nutritional minima below which an organism will die to the gluttonous maxima beyond which an organism will lose its appetite. There is also indication that certain non-human animals have intrinsic ‘thrival needs’ for ‘luxury behavior’ (Lawrence, 1987), such as play, which is usually not considered essential for reproductive fitness. It has been argued, though, that play has longer-term functions for attachment development and the establishment of the dominance hierarchy among conspecifics, and it may also be intrinsically exciting and stimulating to the organism (Spinka & Wemelsfelder 2011). Nonetheless, thrival needs, which are needs in excess of the necessities for survival, are rare in non-human animals and are often suppressed in times of hardship to give priority to the struggles for survival and reproductive success (Stone, 2008).

Thrival needs play a critical role in human societal evolution, however. Unlike non-human organisms that are mostly driven by their survival needs, humans are motivated by their thrival needs as well as their survival needs. Humans are born with a set of limited survival needs, as well as an insatiable thrival desire that generates new needs to be fulfilled after the existing ones are met. Beyond the indispensable minimum required for survival, as Durkheim (1972, p. 175) notes, there is ‘a wider range of conditions and desired ends demanding fulfillment’, and ‘they cannot be quenched’. For example, upon fulfilling their basic biological needs, if conditions permitting, humans will compete for wealth, power, prestige and other goods and services that will make their lives more comfortable, enjoyable and admirable. As thrival needs are derived by humans from their thrival desire after their innate survival needs are met, ‘this creation of new needs is the first historical act’ (Marx & Engels, 1998 [1932], p. 48). That is to say, the first effort to fulfil the derived thrival needs constitutes the beginning of human history.

However, our species, Homo sapiens, has existed for about 300,000 years, why did human desire for thrival lead to no pursuit of prosperous living until the end of the Pleistocene, about 12,000 years ago? This is because thrival desire alone is insufficient for the development of thrival needs and their fulfilment. A necessary precondition for that is the existence of a suitable ecological environment (Bogucki, 1999). In the Pleistocene, the harsh climate of the Ice Age left human ancestors with no choice but foraging for food in the wilderness. Even after the occurrence of the ‘great leap forward’ in human cognition about 70,000 to 50,000 years ago that made Homo sapiens ‘biologically and behaviorally modern humans’ (Diamond, 2017 [1997], p. 39), the human race continued to live in small foraging bands, relying exclusively on the provision of food by nature for survival and reproduction. Human pursuit of prosperous living finally became possible when the global climate began to warm up towards the end of the Pleistocene (Barker, 2006). The change of the glacial environment led to the emergence of farming and animal husbandry, which allowed humans to gain control over the production of their food supply and, consequently, transition from a nomadic hunter-gathering life to settlement and sedentary village living.

The Neolithic Revolution, therefore, marked the beginning of human societal evolution by a new mode of selection – human self-selection. In the pre-Neolithic period, natural selection acted on genes and culture for maximizing the reproductive fitness of the human population. In the aftermath of this revolution, human self-selection came to operate as the primary mechanism of human societal evolution by acting on cultural variants – potentially genetic variants as well – for the pursuit of prosperous living. This new mechanism is called human self-selection mainly for the following reasons. First, human production of food surpluses renders it possible for the fulfilment of the derived thrival needs. Prior to the Neolithic Revolution, humans had the thrival desire without the capability to satisfy the desire. Food production enables humans to increase abundance through labour intensification, and the availability of food surpluses allows humans to engage in ‘luxury activities’ that fulfil their growing thrival needs. Second, the standard for prosperous living is set by humans themselves. Unlike the nutritional minima required for survival and reproductive success, which is biologically determined, what constitutes prosperous living is essentially a human judgment. Wealth, power and prestige are important parameters of prosperous living, but how much WPP is needed to be prosperous enough is up to the members of a society to decide. Third, humans establish institutional rules to regulate the ways in which prosperous living is to be pursued. There are hard-wired behavioural responses such as instincts in genetic adaptation, but the relationship between meme and behaviour is more complex in cultural adaptation, which often involves mechanisms of social control, including persuasion, coercion, material sanction and physical punishment. At the societal level, the linkage between meme and behaviour is established and maintained by the ruling elites through the imposition of institutional regulations (Runciman, 2009). While institutional rules existed in human hunter–gatherer societies prior to the Neolithic Revolution, they were part of the cultural variants subject to natural selection (Read, 2012). In the pursuit of prosperous living, institutional constructions are directed towards the achievement of the thrival goals set by humans themselves. Since humans play a decisive role in these critical areas of societal functioning, the evolution of human societies after the Neolithic Revolution can be described as driven by human self-selection. In Childe’s (2003) words, this is a process of ‘humans making themselves’.

In human societal evolution by natural selection, there is a distinction between cultural adaptations by humans and the selection of adaptive cultural variants by the environment: humans adapt, nature selects. In human societal evolution by human self-selection, on the other hand, the distinction between adaptation and selection is largely collapsed. To pursue thrival beyond survival, humans seek to construct an institutional and technological world according to a ‘blueprint’ that humans draw by themselves. This process of societal construction integrates adaptation and selection into the action of agentic human self-actualization: humans select, humans adapt, where adaptation is in fact an integral part of human self-selection. An important qualification to be added here is that not all members of human society have equal power to affect societal construction: some are able to make rules and others are forced to abide by the imposed regulations.

After the Neolithic Revolution, the pursuit of prosperous living at the societal level took place within a stratified agrarian state, where the opportunities for prosperity were unequally distributed among the members of society (Carneiro, 1970). In human hunter–gatherer societies, societal fitness is essentially the sum of individual reproductive fitness as there are no separate social organizations other than individual members to embody the ‘interest of society’. In a stratified agrarian society, on the other hand, the state emerges as a separate entity that claims to represent the society and demands that all members of society submit to its rule. Separation of the state from the society and the ruling elites from other members of society creates a conflict of interest in group fitness and the resulting class struggles that characterized human societal formations thereafter (Harris, 1979; Marx & Engels, 1848 [1978]). In a non-egalitarian society, the ruling class tends to distribute fewer goods and services to those in the lower strata and more to those in the upper strata, and this unequal distribution of wealth, power and prestige produces a structure of inequality in thrival and prosperity among members of society.

Finally, it should be emphasized that human self-selection in the pursuit of thrival and prosperous living is influenced by the natural environment in which human societal evolution takes place. The climatic conditions and the biophysical resources that nature provides serve as the foundation and affect the outcomes of human self-selection. At the same time, human activities modify the natural environment; in particular, the advancement of modern technologies increasingly blurs the boundary between nature and culture. Human modification of the ecological environment through farming, mining, deforestation, carbon dioxide emissions, among other things, have ‘culturalized’ nature, leaving permanent human impact on the surrounding natural environment. Genetic engineering also raises the possibility of human intervention of the natural process of genetic inheritance, including the transmission of human genotypes. However, despite the growing human influence on nature, human societal evolution remains subject to natural selection in the final analysis. Human self-selection operates under the condition that humans’ basic needs of survival and reproduction are fulfilled, but this condition can be violated by dramatic changes in the natural environment, such as natural catastrophes (e.g. interplanet collision, significant rise of sea levels), depletion of natural resources and global outbreaks of fatal plague. When such situations occur, the pursuit of thrival and prosperous living will be replaced by the struggle for survival and reproductive success, and human self-selection will give way to natural selection.

Conclusion

Evolutionary theory had a major influence on the discipline of sociology. From Spencer to Parsons to Giddens, many well-known sociologists developed their theories by drawing on or criticizing social evolutionism (Sanderson, 1990). Nowadays, despite the fact that the theory of natural selection is no longer popular in social research, the idea of cultural selection has become influential in many fields, including sociology. The present article provides a critique of the notion of cultural selection and proposes the conception of human self-selection as an alternative approach. This approach helps to clarify a number of confusions in the existing literature, but at the same time it also raises many challenging questions for research on the evolution of human societies.

First, the conception of human self-selection draws an important distinction between human social behaviour and human societal attribute. Human social behaviours are activities of individuals directed at other individuals which take place at interpersonal and group levels, whereas human societal attributes are macro-level parameters of a society such as population size, mode of food acquisition, dominance structure and other institutional characteristics. Although societal attributes are impossible to exist in the absence of the activities of individuals, individual activities are not the same as societal attributes. Human self-selection is a mechanism that accounts for the evolution of human societal attributes.

Second, two different notions of cultural selection are identified in the evolutionary study of human societies. ‘Cultural selection’ sometimes means cultural adaptation, parallel to genetic adaptation. As a form of phenotypic adjustment, agentic human activities, including technological and institutional innovations, are subject to natural selection, depending on whether the cultural variants promote human survival and reproductive success. However, ‘cultural selection’ has also been used to denote a process that resembles human self-selection, in which agentic human activities aim at something beyond the maximization of reproductive fitness, such as wealth, power and prestige. ‘Human self-selection’ reconceptualizes ‘cultural selection’ in the second sense as an emergent mechanism of human societal evolution characterized by a new set of selection pressures (e.g. thrival needs) and a distinct fitness criterion (i.e. prosperous living) for assessing the adaptiveness of cultural variants. As such, the processes of ‘dual selection’ (natural selection and human self-selection) are distinguished from those of ‘dual inheritance’ (genetic inheritance and cultural inheritance) in human societal evolution. It should be noted that the reconceptualization of cultural selection proposed here does not in any way diminish the importance of the role culture plays in human societal evolution, for the very qualification of self-selection as specifically human entails a distinctive cultural environment that is characteristic of human society.

Third, the concept of human self-selection also clarifies a confusion about the relationship between human agency and human societal evolution. The human capacity for agency has been considered by many as a critical factor that makes natural selection inoperable in the evolution of human societies (see Turner & Maryanski, 2015). The creative power of human agency is said to enable humans to self-select, changing their cultures and social structures deliberately through cumulative technological and institutional innovations. Collective human ‘emergency decision making’ (Boehm, 1996), for example, has been regarded as capable of mitigating the influence of natural selection. In other words, humans are ‘agentic species that can alter evolutionary heritages and shape the future’ (Bandura, 2006, p. 173). The notion of human self-selection does not reject that argument but serves to qualify it. Human agency alone cannot move humans out of the orbit of natural selection. After the cognitive revolution about 70,000 to 50,000 years ago, humans were anatomically and behaviourally modern, possessing the capacity for agency as humans do today. However, agentic humans still had to forage for food in small nomadic bands in the wilderness for tens of thousands more years before they were finally able to cultivate plants and settle into villages. It is thus the combination of human agency and the global climate change that paved the way for human self-selection.

More specifically, it is the production of food surpluses that made human self-selection finally possible. Domestication of plants and animals per se does not lead to the rise of human self-selection. The transition from food-foraging to food-production probably took a long time, marked by multiple reversals of direction and a coexistence of the two modes of subsistence (Johnson & Earle, 1987). Some believe that food-production initially did not produce a standard of living that was higher than that of food-foraging, for they argue that human hunter–gatherers in fact led an idyllic life with more nutritious food and a plenty of leisure time (see discussions in Barker, 2006). Idyllic or not, the shift from hunting and gathering to grain production and stock raising was most likely out of necessity due to population growth and/or the depletion of food resources in the wilderness (Cohen & Service, 1977; Lewin, 1988). Indeed, intensive farming was more laborious than hunting and gathering, and it served as just another mode of subsistence living under natural selection. The pursuit of prosperous living, however, began when food surpluses became available to certain people in society resulting from a major institutional transformation – the transition from the egalitarian tribal society to the stratified agrarian state.

In a stratified agrarian state, the population is divided into two basic social strata: food producers, for example, farmers and herdsmen, and non-food producers, for example, craftsmen, merchants, soldiers and clerks. A particular group of individuals in the non-food producer stratum consists of the emperor or king and those who assist the emperor/king in running the agrarian state. These individuals constitute the ruling class that wields the largest amount of power. They control the army, secure the border, collect tax revenues and determine the redistribution of the produced goods and services among the people in the different social strata of the state. The rise of such a new societal structure leads to the ‘reorganization of group fitness’ (Michod & Nedelcu, 2003, p. 66). Through labour intensification, more goods and services can be produced, in excess of the minimum that is required to keep those in the lower-level strata productive, and the ‘surpluses’ are then distributed to those in the higher-level strata. The availability of such surpluses enables members of the higher-level strata to live a life that goes beyond mere survival and reproductive success. Therefore, at least initially, the pursuit of prosperous living by a few people was at the cost of making many others struggle for survival and reproductive success.

In a way, the conception of human self-selection falls under what Runciman (1998) calls the new ‘selectionist paradigm’ that regards human societal change as resulting from ‘a process analogous but not reducible to natural selection’ (p. 163). However, treating human self-selection as a mechanism of human societal evolution raises some challenging questions for social research. If human societal evolution is entirely driven by natural selection, which is an exogeneous force beyond human control, the task of social research will simply be to uncover the natural laws of societal evolution to be obeyed in self-conscious human activities. On the other hand, if human societal evolution is driven at least in part by human self-selection, then the goal of social research is not merely to map out the possible trajectories of societal evolution shaped by natural selection but also to find out what humans can do to influence the constitution and development of their societies. In other words, the conception of human self-selection places the future of human society partially on the shoulders of humans themselves. However, the inclusion of this constructive component of human self-selection as a causal factor influencing the change of human society turns a segment of the ‘in-itself’ natural evolution into a ‘for-itself’ human history, allowing humans to determine the course of their societal development.

For example, it is up to humans to decide what type of prosperous living they want to pursue after their basic survival needs are met. Under natural selection, organisms strive to survive and reproduce, and fitness is the distribution of the given genotypes in a population: the more widespread, the better fit. Under human self-selection, however, the fitness criterion for prosperous living is set by humans themselves. How much economic growth is to be targeted for? Should economic development be prioritized over economic equality? What type of political structure is more desirable? Is decentralization of power better than centralization of power? When it comes to cross-societal comparisons, how to assess different ways of living and different cultural traditions? How to compare different religions, ideologies, philosophies of life and other belief systems in the world? Obviously, different people have different answers to those questions depending on, among other things, what society they are from and what positions they occupy within the society.

For the most part, though, the disagreement among people about the criterion for prosperous living lies not so much in what they would like to have as in what they think they can and should have. Everyone would like to lead a life that will make them happy, healthy and fulfilled, but, in reality, people have to weigh the pros and cons of the available options and choose what they consider to be the best. There are many challenges people face in making such decisions, and the two important ones are (a) unintended consequences and (b) interhuman competition. Humans are more or less rational beings, but human ‘rational choices’ may produce unintended irrational consequences. Human intentional action is only one link in the complex causal chains of events and humans are not in a position to know the long-term effects of all their actions. For instance, the invention of plastics was truly revolutionary because, for the first time, humans were freed from the limits of nature and able to produce virtually endless material wealth without exhausting precious natural resources. However, this excitement was soon dampened by the discovery that plastics can cause nearly irreversible damage to the environment and human health. Another example is the population control effort made in China. The imposition of the ‘one child’ policy had successfully curbed the rapid population growth in the country, demonstrating the power of human self-selection in regulating societal human reproduction. Four decades later, this policy had to be abandoned due to the emerging problems of labour shortage and an aging population. Thus, what seems to be a good choice for prosperous living in the short run may turn out to be a bad decision in the long run.

The second issue is interhuman competition. The thrival desire that humans have is the internal selection pressure for prosperous living under human self-selection. Although they all have unlimited desire for thrival, humans in different societies and in different positions within a society pursue different levels of prosperous living. This is because it is not the thrival desire per se but the competitions among humans – individuals, groups and societies – for the fulfilment of the derived thrival needs that determine the fitness criteria in human self-selection. After humans climbed to the top of the food chain in the animal kingdom, interhuman competition has become the main external selection pressure that drives human societal evolution. Humans compete for survival and thrival both intra-societally and inter-societally, and this competition leads to group conflicts within society and warfare among societies. As a result, different human societies, and different human groups within a society, pursue different types of prosperous living.

Given the limitations of human knowledge and the competitions among humans, what is going to be the future of human societal evolution driven by human self-selection? Some scholars believe that the future world will be ‘decentered’, allowing different forms of society and different types of prosperous living to coexist with no preferential ranking or order (McLaughlin, 2012), but others argue that human societies are moving in the direction of increasing societal complexity, for ‘when pitted against each other…the simpler society almost invariably succumbs to the more complex one’ (Carneiro, 1987, p. 113). This social complexity argument has an important offshoot: the belief that there is a non-stoppable trend towards technological advancement. In inter-societal competition, humans compete for the limited natural resources to satisfy their growing thrival needs. The more technologically advanced societies have a greater probability of success, and this process creates ‘inter-societal selection for greater level of technological development’ (Lenski, 2005, p. 80). Indeed, the motivation to seek technological supremacy is a powerful force behind various ‘modernization programs’ in the world. The pace of technological development has accelerated dramatically in the last several hundred years, starting with the Industrial Revolution in the late 1700s and early 1800s, followed by the Digital Revolution in the late 1900s and early 2000s. The world is now witnessing a global Robotic Revolution in which artificial intelligence is penetrating virtually all aspects of human life.

While technological advancement enhances human capacities to deal with the world they live in, it also brings about foreseeable and unforeseeable negative consequences for human prosperous living. The more powerful the technology gets, the more damage it can cause to humans and their habitat. Is it possible for humans to slow down their technological march for conquering nature and outdoing each other? To balance development and sustainability? To live in peace and harmony among themselves and with nature? In sum, do Homo sapiens have the wisdom and capability to pursue thrival and prosperity without jeopardizing their survival and reproductive success on this planet? This article, while providing no direct answer to those questions, proposes a perspective that embeds such questions in the context of human societal evolution and regards the effort of social research as part of human self-selection. In this sense, this article takes a position similar to that of Habermas (1984) which attaches importance to the role human reflective learning plays in the development of history. As a discipline that studies human society, sociology has a unique contribution to make to the understanding of the opportunities and challenges associated with human self-selection in human societal evolution.