Ecologies change, and so do the challenges and opportunities afforded by those ecologies. One source of ecological change is predictable and cyclical: The seasons. Seasons affect people’s natural and social ecologies, and do so in countless ways. Consequently, there are seasonal cycles in numerous psychological phenomena, including mood, memory, music preferences, aggression, altruism, and mating behavior (Hohm et al., Reference Hohm, Wormley, Schaller and Varnum2024b). Many of these effects appear to be functional responses to changes in the ecologies that humans inhabit (e.g., seasonal changes in resource availability). The affordance management framework articulated by Ko and Neuberg provides a tool that can be used to better understand and predict how seasonal effects on psychological processes differ across the lifespan.

To illustrate its utility, consider a well-known phenomenon: Seasonal depression during wintertime. Less well-known is the finding that seasonal depression – which is common among young adults – is less prevalent among older adults. This moderating effect of age is well-documented (Bjorvatn et al., Reference Bjorvatn, Saxvig, Waage and Pallesen2021; de Craen et al., Reference de Craen, Gussekloo, van der Mast, Cessie, Lemkes and Westendorp2005; Holloway & Evans, Reference Holloway and Evans2014; Lukmanji et al., Reference Lukmanji, Williams, Bulloch, Bhattarai and Patten2019; Magnusson & Stefansson, Reference Magnússon and Stefánsson1993; Rastad et al., Reference Rastad, Sjödén and Ulfberg2005), but it has yet to be explained. An affordance-management framework can help do so.

Previous research has suggested that seasonal changes in mood may reflect an adaptation that preserves energy under ecological circumstances characterized by limited resources (Levitan, Reference Levitan2007; Nesse, Reference Nesse2000). Just as hibernation (in bears) conserves energy during seasons when foraging opportunities are scarce, seasonal depression (in humans) might serve a similar function. Here is where the life-history part comes in: Judicious allocation of energetic resources may be particularly important among young adults. In addition to having higher metabolism than older adults (Henry et al., Reference Henry2000), younger adults typically invest greater physical, cognitive, and emotional resources to achieve goals such as status-acquisition, mate-attraction, and reproduction. Because of these higher demands, younger adults may especially benefit from a sensitivity to seasonal changes, investing energetic resources when resources are plentiful and conserving energy when resources are scarce. Older adults are likely to benefit less (not only because they have reduced energetic demands, but also because benefits accruing to reproductive fitness are correspondingly reduced for post-reproductive individuals). The upshot: From an affordance-management perspective, seasonal cycles in mood are expected to be reduced among older adults.

A further implication of this perspective on seasonal depression is that analogous seasonal cycles are expected to occur in behavioral domains that are particularly relevant to younger adults. One such domain is mating. There is abundant evidence of seasonal cycles in behavioral indicators of mating motives – such as condom sales and Google searches for pornography – and in birthrates (Herold et al., Reference Herold, Woodard, Roetzheim, Pamies, Young and Micceri1993; James, Reference James1990; Levin et al., Reference Levin, Xu and Bartkowski2002; Markey & Markey, Reference Markey and Markey2013; Martinez-Bakker et al., Reference Martinez-Bakker, Bakker, King and Rohani2014; Wellings et al., Reference Wellings, Macdowall, Catchpole and Goodrich1999). The specific nature of these seasonal cycles varies across societies and can be partially attributed to cultural phenomena that transcend the scope of an affordance management framework (e.g., people engage in more mating behavior during the holidays), but only partially. In many societies, seasonal cycles in birthrates are driven by physiological and behavioral sensitivity to seasonal cycles in the availability of energetic resources in local ecologies (Bronson, Reference Bronson1995; Ellison, Reference Ellison2008). It follows that seasonal changes in mating behavior may covary with seasonal changes in mood, and there is evidence that this is so (Davis & Levitan, Reference Davis and Levitan2005). This finding further substantiates the conceptual analysis summarized in the previous paragraph and suggests additional hypotheses as well. For instance, there might be a relatively gradual effect of aging on incidence of seasonal depression among men, but a sharper age-related reduction in incidence among women, corresponding to the timing of menopause. Additionally, even within a population of young adults, seasonal cycles in mood may be reduced among women using hormonal contraceptives.

There may be additional implications for seasonal variation in additional psychological phenomena. For example, recent research has revealed seasonal cycles in Americans’ moral values pertaining to ingroup loyalty, respect for authority, and bodily purity (Hohm et al., Reference Hohm, O’Shea and Schaller2024a). These “binding” moral values (Graham et al., Reference Graham, Nosek, Haidt, Iyer, Koleva and Ditto2011) decrease during summertime and, more briefly, during winter holidays – the inverse of the seasonal pattern observed for mating behavior in the United States. Moral values are associated with the activation of complementary motivational systems (Rohan, Reference Rohan2000); and, in particular, endorsement of binding moral values is associated with increased risk-aversion (Feldman, Reference Feldman2021) and decreased willingness to engage in sex (Barnett et al., Reference Barnett, Martin and Melugin2018). An intriguing implication is that, like seasonal cycles in mood, seasonal cycles in binding moral values may also be more pronounced among younger adults compared to older adults. This hypothesis has not yet received empirical attention.

The preceding paragraphs are speculative, of course, and some of those speculations may prove to be wrong. We offer these speculations – new explanations for previously unexplained findings and novel hypotheses that have yet to be tested – to further illustrate the generative utility of the affordance management framework outlined by Ko and Neuberg. In addition to its many other merits, this framework has the potential to produce new discoveries and deeper insights regarding the seasonal nature of human nature.