Organisms don't explore for exploration's sake: exploratory psychology is regulated by inputs from multiple adaptations dedicated to processing information from different domains of ancestral adaptive relevance. As holistic representations of environments, imaginary worlds simulate multiple adaptive problems, solutions, and outcomes, thereby engaging numerous emotional systems and providing potentially useful information. Their popularity is thus best understood in terms of the full spectrum of information domains they comprise.

Dubourg and Baumard posited that preferences for exploration are the key to the popularity in imaginary worlds. This commentary argues that other forms of exploration may also account for the success and appeal of specific types of imaginary worlds, namely self-exploration within interactive imaginary worlds such as videogames.

The authors argue that children prefer fictions with imaginary worlds. But evidence from the developmental literature challenges this claim. Children's choices of stories and story events show that they often prefer realism. Further, work on the imagination's relation to counterfactual reasoning suggests that an attraction to unrealistic fiction would undermine the imagination's role in helping children understand reality.

If recent exploratory traditions tap into evolved psychological dispositions to explore, wouldn't humans be expected to have drawn on such dispositions long before the written word? Trickster oral traditions fill this role in all levels of society, affluence, and on all continents, inverting the boundaries of social worlds and those between humans and animals, fostering cultural innovation.

Why has fiction been so successful over time? We make the case that fiction may have properties that enhance both individual and group-level fitness by (a) allowing risk-free simulation of important scenarios, (b) effectively transmitting solutions to common problems, and (c) enhancing group cohesion through shared consumption of fictive worlds.

The authors do not compare readers who prefer imaginary world fiction to readers with other reading preferences, failing to rule out the hypothesis that their findings apply to all readers. The authors also do not test their hypotheses against plausible alternative ones, several of which are suggested here.

Dubourg and Baumard's paper takes a different, and fruitful, approach to the study of imaginary worlds than what is usually found in Media Studies, but omits certain circumstances and influences that shaped their history; this article argues that psychological or behavioral factors are not enough to explain the growth of imaginary worlds, even as they may be important influences.

Imaginary worlds allow us to safely develop, crystallize, and criticize our moral values – at times even serving as catalysts for change in the real world. Fans of imaginary worlds sometimes form groups to advocate for social change in the real world, and it is part of Leftist ideology to imagine radically different, possible futures aligned around shared moral values.

We received several commentaries both challenging and supporting our hypothesis. We thank the commentators for their thoughtful contributions, bringing together alternative hypotheses, complementary explanations, and appropriate corrections to our model. Here, we explain further our hypothesis, using more explicitly the framework of evolutionary social sciences. We first explain what we believe is the ultimate function of fiction in general (i.e., entertainment) and how this hypothesis differs from other evolutionary hypotheses put forward by several commentators. We then turn to the proximate features that make imaginary worlds entertaining and, therefore, culturally successful. We finally explore how these insights may explain the distribution of imaginary worlds across time, space, age, and social classes.