Some evolutionary theorists and cognitive scientists like Richard Dawkins (The God Delusion, 2006) and Pascal Boyer (The Naturalness of Religious Ideas: A Cognitive Theory of Religion, 1994) , take religion as a spandrel, a by-product of mental modules that originally supported the evolutionary adaptation of our ancestral hunter-gatherers to some natural surroundings. In its extreme form the by-product theory sees religion as a harmful virus (or meme), effective in copying itself and spreading in culture. Its effect on morality is disastrous: it is a major source of conflict and evil.
On the other hand, there are evolutionary biologists who think that religion is itself an adaptation. David Sloan Wilson (Darwin's Cathedral , 2002), for instance, argues in contrast to the by-product theory that religions survive because of their ability to enhance ingroup morality and cohesion. This gives religious groups adaptive advantage over other groups in evolution—purely in material terms.
Many of the recent evolutionary approaches to the birth of Christianity are characterized by the use of Rodney Stark’s sociological analysis of the reasons for the rise of Christianity (The Rise of Christianity, 1996). From the viewpoint of evolution, Stark’s analysis seems to present a clear case of group selection: Christianity spread through open networks and improved the quality of life of those who joined Christian communities. Christian groups also survived better in times of famine and plague and therefore their relative percentage of the population increased. In Stark’s view, all this was driven by Christian doctrine and morality: “Central doctrines of Christianity prompted and sustained attractive, liberating and effective social relations and organizations.”
A problematic feature in this positive reception of Stark is that Stark himself is a supporter of Intelligent Design. He thinks it is possible to apply the evolutionary viewpoint of variation and selection of the fittest in the study of cultural “evolution” but that happens only “within the ‘species’ known as human cultures or, ….within the ‘species’ called religion.” It is clear that this kind of evolutionary analysis is quite restricted as compared with Darwinian evolutionary analysis which allows reasoning across species. Furthermore, although Stark, as a sociologist, is able to offer new insights for the analysis of the birth of Christianity, his research approach and analyses have been criticized by experts in early Christian studies for anachronisms and inadequate analysis of source texts in their original languages. Thus, as far as Stark’s research raises questions that are relevant for cultural evolutionary analysis, the results have to be assessed in the light of original sources and placed in the setting of a proper cultural evolutionary theory.
One candidate for an overall evolutionary theory that could integrate the research on early Christianity was provided by Gerd Theissen already in 1984: Biblical Faith: An Evolutionary Approach (reprinted in 2007 and later). The book seeks to explain and interpret biblical history and faith in the framework of Darwinian evolution. However, Theissen’s approach is highly abstract and theological; he analyses the three main articles of faith—faith in God, in Jesus and in the Holy Spirit—and their overall development in Judaism and early Christianity. In particular, Theissen’s way of setting cultural evolution against biological evolution has been criticized by evolutionary theorists. In Theissen’s view, “Culture begins where human beings reduce the pressure of selection by intelligent behaviour, i.e. it also makes human life possible where it would have no chance of survival without its deliberate intervention.” Moreover, Theissen thinks that Jesus’ life and proclamation—followed by the evolution of Christian faith—granted unconditional value to forms of life that would become extinct under the raw forces of natural selection: to the sick, the weak, the meek, strangers and slaves. Theissen interprets Jesus’s role in cultural evolution as “mutation”.
John Teehan makes a slightly different case in his In the Name of God: The Evolutionary Origins of Religious Ethics and Violence (2010). Teehan argues that morality and altruism, even in their Christian form, can be seen as the products of continuous biological and cultural evolution—without setting cultural evolution against biological evolution, or assuming a “mutation” in evolutionary development. Teehan also casts light on the other side of the coin, by tracing the roots of religious violence back to the same evolutionary processes.
Overall, Theissen’s and Teehan’s work bring up some important aspects in evolutionary analysis that also need to be taken into account in the present project: the interplay between altruism and retaliation in cultural evolutionary processes, and religious violence and evil. Since violence often aims at suppressing outsiders and outgroups it can be seen as culturally generated selective force. If this possibility of enhancing adaptation by aggressive suppression of competitors is not kept in mind, evolutionary analysis may become an all too tidy story of successful adaptation to challenges imposed by the environment.
In the present globalized culture the interaction between different ethnic and religious groups is steadily increasing. Analytical historical work cannot offer direct remedies for these acute problems but it can help to differentiate to which extent religious identities and morality are rooted in the cognitive propensities of the human mind that evolution has produced, and to which extent they express culturally generated and transmitted representations and practices. Some basic cognitive capacities and propensities that the human mind has acquired in the course of its evolutionary history—for instance, such as ingroup/outgroup differentiation and ingroup bias—are perhaps impossible to uproot. However, the mere knowledge of their presence in the human mind and their traces in the history may help to avoid some of their most negative effects in the future.
Knowledge about the mechanisms that contributed to the success of Christianity in its first centuries may also inspire the present Christian communities to critically assess their present self-understanding. For instance, “the success story” of Christianity may prove out to be resulting from moral capacities that all humans share, or the success may turn out to be based on suppression of others. In both cases there are reasons for critical self-reflection. On the other hand, if there is something distinctively positive in the Christian tradition it is possible to ask if these parts of the tradition are also applicable in the present.