In the target article, Singh makes some suggestions as to when shamanism should decline, proposing, for example, that shamanism should decline when people stop believing that invisible forces are powerful, that human beings can interact with them, and that trance reveals supernatural power. Singh's suggestions, however, do not explain the decline. Instead, they only move the question one step further: Why did people stop believing in invisible forces?

One common suggestion to explain the decline of magic is Malinowski's theory (cited by Singh) that people believe less in magic when they start being better able to deal with uncertainty in their daily lives (Malinowski Reference Malinowski1954). Yet, it is striking that the decline of shamanism (and, more generally, magic) started before any real advancement of modern medical techniques. For example, the early modern English stopped using magical techniques and believing in supernatural agents and supernatural powers before the alternative (science) started showing any effect. As Thomas (also cited by Singh) notes in Religion and the Decline of Magic:

How can the decline of magic be explained? An important factor might be the unprecedented increase in living standards experienced by English people (and more generally, by Europeans and Americans) from the seventeenth century onward (Allen Reference Allen2001; Broadberry et al. Reference Broadberry, Campbell, Klein, Overton and Van Leeuwen2015; Morris Reference Morris2013). Indeed, affluence has predictable effects on human psychology (for a recent review, see Pepper & Nettle Reference Pepper and Nettle2017) and can alter the dynamic of cultural evolution (Baumard & Chevallier Reference Baumard and Chevallier2015; Baumard et al. Reference Baumard, Hyafil, Morris and Boyer2015). In particular, recent research inspired by life history theory has shown that, in a harsh environment, when resources are low and unpredictable, individuals tend to be more short-term oriented, more risk averse, and more conservative. By contrast, in an affluent environment, individuals are future oriented, risk prone, and open minded.

This variability makes sense from an evolutionary perspective. When resources are high:

1. 1. Organisms can allocate resources to activities that have high but delayed benefit because they can afford to wait (Houston & McNamara Reference Houston and McNamara1999).

2. 2. Organisms can allocate resources to high-risk/high-reward activities with unpredictable benefits because they can afford to take a loss (Nettle Reference Nettle2009).

3. 3. Organisms can invest in activities that have a moderate return on investment because they already have filled more vital and basic needs (food, self-protection, social status) (Kenrick et al. Reference Kenrick, Griskevicius, Neuberg and Schaller2010).

In line with the predictions of life history theory, a range of studies have shown that the level of resources has a strong effect on:

1. 1. People's relation to the future (Cornelisse et al. Reference Cornelisse, Van Ast, Haushofer, Seinstra and Joels2013; Ifcher & Zarghamee Reference Ifcher and Zarghamee2011; Lerner et al. Reference Lerner, Li and Weber2013; Yesuf et al. Reference Yesuf and Bluffstone2008)

2. 2. People's tendency to invest in high-risk/high-reward actions (Cohn et al. Reference Cohn, Engelmann, Fehr and Maréchal2015; Dohmen et al. Reference Dohmen, Falk, Huffman, Sunde, Schupp and Wagner2011; Guiso & Paiella Reference Guiso and Paiella2008; Guiso et al. Reference Guiso, Sapienza and Zingales2013; Kandasamy et al. Reference Kandasamy, Hardy, Page, Schaffner, Graggaber, Powlson and Coates2014) and to be optimistic and confident about one's ability to influence the environment (Haushofer Reference Haushofer2013; Lundberg et al. Reference Lundberg, Bobak, Malyutina, Kristenson and Pikhart2007; Poortinga et al. Reference Poortinga, Dunstan and Fone2008) and

3. 3. People's tendency to be explorative, open-minded, and non-conformist (Cashdan & Steele Reference Cashdan and Steele2013; Gelfand et al. Reference Gelfand, Raver, Nishii, Leslie, Lun, Lim, Duan, Almaliach, Ang, Arnadottir, Aycan, Boehnke, Boski, Cabecinhas, Chan, Chhokar, D'Amato, Ferrer, Fischlmayr, Fischer, Fülöp, Georgas, Kashima, Kashima, Kim, Lempereur, Marquez, Othman, Overlaet, Panagiotopoulou, Peltzer, Perez-Florizno, Ponomarenko, Realo, Schei, Schmitt, Smith, Soomro, Szabo, Taveesin, Toyama, Van de Vliert, Vohra, Ward and Yamaguchi2011; Murray et al. Reference Murray, Trudeau and Schaller2011)

Life history theory thus predicts that, when an individual is poor and must focus on a small range of priorities, most actions should appear as hopeless, risky, and counterproductive. By contrast, when the same individual is rich and has filled basic needs, a lot of opportunities now must appear as fruitful, safe, and promising; therefore, the individual should be optimistic and confident in the ability to transform the world. Because such individuals have filled their basic needs, they also should see materialistic rewards as less interesting and find exploratory and gratuitous actions more enjoyable. They also should be less afraid of social disapproval and, consequently, more independent minded.

The rising standards of living experienced by Europeans thus could have changed individuals' psychology from a pessimistic, conformist, and conservative outlook to a more optimistic, non-conformist, and progressive one. As a result, Europeans would have started being more confident in the capacity to change the world, to propose new theories, and to test them. In turn, this optimism would have made the experimental method and the rationalistic approach of psychology more appealing. This is despite the fact that, in the seventeenth century, there was no evidence yet that experiments and science could really improve people's situations. As Thomas (Reference Thomas1971b) writes: “The change was less a matter of positive technical progress than of an expectation of greater progress in the future … It marked a break with the characteristic medieval attitude of contemplative resignation.”

To put it in another way, we are claiming that, because science is highly counterintuitive (McCauley Reference McCauley2011) and requires a lot of time and resources, it is to be expected that individuals will deem science worth attention and investment only when they start being optimistic and patient.

To conclude, evolutionary psychology has the potential to explain both the recurrence of the belief in shamanism (as in Singh's article) and its variability.