Comparative Thanatology of Primates: Historical, Evolutionary and Empirical Approaches

概要

Nonhuman primates and other animals have been observed inspecting, protecting, retrievi ng, carrying, or dragging the carcasses of their conspecifics for centuries, yet little scientific attention has been paid to such behavior. Given that there is a significant gap in the fossil and archaeological record regarding how early humans lived extant primates may provide v ital insight into how and in which hominins dealt with their dead. This thesis aimed to unc over patterns of similarity and differences among non-human animals with non-human pri mates but also chimpanzees with humans. The author examined both historical and recent evidence of thanatological responses in non-human animals and divide them into two cate gories: direct contacts (physical contact with the body) and secondary interactions (guardin g the corpse, vigils, and visitations). He drew on data from comparative perception and cog nition studies (with a focus on corvids, proboscids, cetaceans, and primates) to investigate the cues that these animals use to detect life and death in others, as well as the proximate and ultimate drivers behind their abilities to do so. Corpses have static clues to animacy (fo rm and texture) like agents, but they don't have dynamic cues like objects (self-propelled m otion and contingency). He, then, suggested the term "animacy detection malfunction," wh ich refers to the conflicting cognitive processes when encountering a corpse, caused by vis ual mismatches that cause expectation violations. Similar sensory cognitive processing proc esses for dealing with corpses have been observed in these four taxa, suggesting that their evolution may have been influenced by complex social settings. Additionally, through his re litterature review, he assessed the evolutionary drivers of grief with a focus on mammal ta xa. Finally, he proposed an integrated model of Life-Death Awareness in which the agency s ystem utilizes brain circuitry dedicated to recognizing life. Furthermore, he conducted a ser ies of experiments using eye-tracking methods to uncover chimpanzees’ attentional patter ns towards death-related stimuli. He hypothesized that chimpanzee skulls with facial chara cteristics would be seen similarly to chimpanzee faces and hence be vulnerable to the same biases. Overall, the chimpanzees preferred conspecific-related stimuli (especially chimp fa ces and skulls in forward-facing and to a lesser degree diagonal orientations), and they paid more attention to the teeth. He propose that chimpanzee skulls maintain important, face-l ike characteristics that, in turn, trigger a domain-specific face module in their brains, direct ing their attention. Another avenue involved presenting live and dead animal photos. The r esults demonstrate that chimpanzees stare substantially more at images of live animals tha n images of dead animals while also detecting living "standing" animals more quickly than d eceased "prone-supine" animals, consistent with the animate monitoring hypothesis and si milar results shown in other eye-tracking studies using humans This thesis lays the ground work for future research into the elements that influence chimpanzees’ perception and un derstanding of death-related stimuli and shed a light into the evolutionary foundations beh ind these responses.