Finally, the third condition comprised three skulls of elephant matriarchs, one of an individual known to the group while alive. Similarly, in the second condition, the skull of an elephant was presented alongside the skulls of a buffalo and a rhinoceros. The first condition consisted of an elephant skull, elephant tusk and a piece of wood. Their experiments consisted of systematically placing three objects in a line, 1 m from each other, order randomized in each trial and placed at 25–30 m from the nearest elephant group. Noticing this natural propensity towards interaction with conspecific bones by wild African elephant, and inspired by Iain Douglas-Hamilton's so-called ‘crude experiments' three decades before, Karen McComb and colleagues devised an experiment to empirically measure how their interest contrasted with other objects positioned in the environment. During a study of elephant carcase decomposition, the skull was transported as far as 100 m from the original site by other elephants. Long known to elephant researchers, interest in dead conspecifics is not only limited to carcases but also extends towards conspecific bones and tusks. Elephants: observations and empirical researchĮlephant post-mortem attentive behaviour has been documented in all three extant species of elephants. However, there is one study reporting similar behavioural responses in bovids ( Bos javanicus) to both conspecific and non-conspecific bones, though neither as marked nor as elaborate as seen in elephants. Elephants appear to be unusual in showing extended attention to dead conspecifics long after they decompose, often interacting with their skeletons for protracted durations. Non-human animal interest in skeletons is not reported in the literature apart from records of osteophagia mostly observed in ungulates where the targets typically include horns, hoofs and long-bones, usually explained as a form of nutrient consumption. Behavioural responses such as physical manipulation of the corpse, vigils and visitations are strikingly similar among these two taxa. What goes on in the chimpanzee's mind when they see such a sight in the forest? We are able to draw some conclusions based on their behaviour when they encounter dead individuals, but deciphering their actual thoughts remains speculative-Christophe Boesch Ĭhimpanzees and elephants share some curious traits they are large-brained, long-lived animals with prolonged development, live in complex societies, are capable of mirror self-recognition and display protracted interest towards injured and dead conspecifics. We suggest that chimpanzee skulls retain relevant, face-like features that arguably activate a domain-specific face module in chimpanzees' brains, guiding their attention. The results showed that chimpanzees attended: (i) significantly longer towards conspecific skulls than other species skulls (particularly in forward-facing and to a lesser extent diagonal orientations) (ii) significantly longer towards conspecific faces than other species faces at forward-facing and diagonal orientations (iii) longer towards chimpanzee faces compared with chimpanzee skulls and skull-shaped stones, and (iv) attended significantly longer to the teeth, similar to findings for elephants. Overall, supporting our hypotheses, the chimpanzees preferred conspecific-related stimuli. We theorized that chimpanzee skulls retaining face-like features would be perceived similarly to chimpanzee faces and thus be subjected to similar biases. Lastly, we tested their attention towards specific regions of chimpanzee skulls. Additionally, we compared their visual attention towards chimpanzee-only stimuli (faces/skulls/skull-shaped stones). We tested chimpanzees' visual attention to images of conspecific and non-conspecific stimuli (cat/chimp/dog/rat), shown simultaneously in four corners of a screen in distinct orientations (frontal/diagonal/lateral) of either one of three types (faces/skulls/skull-shaped stones). Chimpanzees exhibit a variety of behaviours surrounding their dead, although much less is known about how they respond towards conspecific skeletons.
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