Great apes reach momentary altered mental states by spinning

Great apes reach momentary altered mental states by spinning. Adriano R. Lameira & Marcus Perlman. Primates, Mar 14 2023. https://link.springer.com/article/10.1007/s10329-023-01056-x

Abstract: Among animals, humans stand out in their consummate propensity to self-induce altered states of mind. Archaeology, history and ethnography show these activities have taken place since the beginnings of civilization, yet their role in the emergence and evolution of the human mind itself remains debatable. The means through which modern humans actively alter their experience of self and reality frequently depend on psychoactive substances, but it is uncertain whether psychedelics or other drugs were part of the ecology or culture of pre-human ancestors. Moreover, (nonhuman) great apes in captivity are currently being retired from medical research, rendering comparative approaches thus far impracticable. Here, we circumvent this limitation by harnessing the breadth of publicly available YouTube data to show that apes engage in rope spinning during solitary play. When spinning, the apes achieved speeds sufficient to alter self-perception and situational awareness that were comparable to those tapped for transcendent experiences in humans (e.g. Sufi whirling), and the number of revolutions spun predicted behavioural evidence for dizziness. Thus, spinning serves as a self-sufficient means of changing body-mind responsiveness in hominids. A proclivity for such experiences is shared between humans and great apes, and provides an entry point for the comparative study of the mechanisms, functions, and adaptive value of altered states of mind in human evolution.

Discussion

Our findings show that great apes spin at speeds that induce physiological “highs” in humans. In untrained humans, spinning at similar rates inescapably produces severe dizziness (we invite the reader to try the observed average rotational speed, length or number of bouts performed by great apes reported here for instant validation). Notably, by comparing “recreational” spinning behaviour of apes to professional spinning in humans, our analyses were inherently conservative. Our findings, while exploratory, provide a proof of concept and a new charter for the study and comparison of spinning and altered mental states between humans and great apes.

Our preliminary findings point to several directions for the future study of spinning behaviour in apes and other species. One is to investigate questions related to evo-ecological constraints on spinning. For example, differences in spinning between orangutans (which are mostly arboreal) and gorillas (which are mostly ground-dwelling) could suggest neurological adaptation against motion sickness or vertigo (with faster speeds/more revolutions required for arboreal species to reach dizziness), similar to the reduction of the vestibular cerebellum observed in ballerinas and figure skaters (Nigmatullina et al. 2015). Differences in certain anatomical features between species may also help them leverage more or fewer revolutions when spinning (e.g. the gorillas never used foot grips, while the orangutans often did).

Our findings also raise interesting questions concerning whether this behaviour is performed more frequently by a particular age class or sex, for example, as part of play by juveniles or as part of male display. Because this behaviour in great apes appears to be idiosyncratic, performed by certain individuals rather than occurring across populations, we anticipate that answering these questions will pose an empirical challenge. If attainable, such effort could help provide new insight into the motivation for spinning behaviour and its ontogeny.

More conclusive comparisons between species, as well as between age classes and sexes, could be made possible by controlling for the proportions in which the relevant groups occur in captivity. For example, our findings suggest that bonobos—who are relatively scarce in captivity compared to chimpanzees, but were conversely well represented in our dataset—may more frequently engage in rope spinning than their sister species. Unexpectedly high rates of occurrence in a species with relatively small population sizes in captivity could suggest a higher predisposition to engaging in behaviour that leads to altered states.

Comparisons of captive and wild populations based on more data could also inform whether this behaviour is more likely to occur in animals in captivity, where they might engage in spinning and experience the ensuing state of dizziness as a way of overcoming low environmental stimulation or boredom. However, comparisons using data on wild individuals will probably be limited because recordings of them are rare and idiosyncratic (e.g. footage of wild mountain gorillas was present in our data, though this was the result of video coverage of some gorilla groups as a consequence of tourists filming them).

Although beyond the scope of analysis here, we have also observed videos of rope spinning by other primate species, including gibbons and monkeys. Future research may seek to determine whether other primates spin as frequently as great apes and in such a way that elicits dizziness and altered mental states. Increasing phylogenetic distance will, however, reduce interpretative power based on the physiological and cognitive homology of these species with humans.

To establish clear comparative benchmarks for future ape-human comparisons, it would be relevant to determine the minimum spinning speeds and lengths of time engaged in spinning necessary to induce altered states in humans, and how training affects and extends these limits. Ethnographic and anthropological studies of how children and adults use spinning and other non-pharmacological means to deliberately disrupt body and situational awareness (e.g. swings, slides, rollercoasters, bungee jumping) could provide complementary information about the role that these experiences play in our lives and, by extension, those of our ancestors over evolutionary time. Interestingly, some accredited zoos are reported to have re-used equipment from children’s playgrounds as enclosure enrichment for apes (R. Shumaker, personal communication). Widespread adoption of devices that make up typical children’s playgrounds for use in great ape facilities could provide dynamic stimulation and motoric challenge to individuals, while potentially helping to reveal more comprehensively, and in a controlled fashion, how and why great apes engage in mind-altering behaviours.