1Anthropology, Indiana University, 2Life Sciences, Indianapolis Zoo, 3Krasnow Institute, George Mason University
Saturday 8:00-8:15, Ballroom C
Of the extant primates, only twenty nonhuman species have been studied by sleep scientists. Notable sampling gaps exist, including large bodied hominoids such as gorillas (Gorilla gorilla), orangutans (Pongo spp.), and bonobos (Pan paniscus), for which data have been characterized as high priority. Here, we report the sleep architecture of three female and one male orangutan (Pongo spp.) housed at the Indianapolis Zoo. Sleep states were identified by scoring correlated behavioral signatures (e.g., respiration, gross body movement, muscle atonia, random eye movement, etc.). The behavioral analysis differentiating sleep states were scored in one-minute epochs, at 8x real time speed. The captive orangutans were focal subjects for a total of 42 nights (535.9 h) recorded. We found that orangutans slept an average of 9.20 h (range: 5.93-10.8 h) nightly and were characterized by an average NREM of 8.17 h (range: 5.47-9.9 h) and REM of 1.04 (range: 0.43-2.07 h) per night. In addition, to assess whether the orangutan species typical sleep architecture (STSA) is within the human range, we compared previously published values of human sleep architecture (HSA) to that of the data generated in this study. NREM % and REM % were significantly different in both chimpanzees and humans when compared against orangutans—chimpanzee values being intermediate between that of orangutans and humans. With increased stability, habitually terrestrial hominins may have benefited from higher quality sleep compared to the vagaries of arboreal sleep. This suggests that the advent of HSA was coincident with the emergence of Homo erectus.
Funding was prodived by the following institutions: Indiana Academy of Science, American Society of Primatologists, Sigma Xi