Viewing of self and nonself images in a group of captive orangutans (Pongo pygmaeus Abellii)

Orangutans (Pongo pygmaeus) recognize their own past actions

The ability to recognize oneself in a mirror is known as self-recognition, whereas delayed self-recognition is the ability to recognize the relationship between current self and past actions. While 3-year-old human children have self-recognition without the ability for delayed self-recognition, 4-year-old human children demonstrate the capability for both. Chimpanzees, the most closely related species to humans, have displayed the ability for delayed self-recognition. However, little is known about whether this ability is shared among all hominid species. In this study, we examined whether orangutans, the most distantly related species to humans within the hominid group, could recognize their own past actions using the preferential-looking paradigm. Our results demonstrated that orangutans were able to discriminate between a delayed video of themselves presented after a 2-s delay and a recorded video of the day prior. This suggests that orangutans have the ability to relate their own past actions to current actions, although we found no evidence of self-directed behaviour. We believe these findings will contribute to our growing understanding of hominid self-recognition.

Note on social behavior of long-term captive female orangutans (Pongo pygmaeus abellii)

Some observations of social behavior of two aging female orangutans with a younger male son of one were made in an outdoor and in an indoor enclosure during the day. These included social distance, grooming, and locomotion plus wrestling and genital stimulation. As noted 15 years earlier, the two old females were never in contact with each other. Each showed contact and noncontact with the younger male. No clear social relation between the females was evident. Careful study of aging zoo populations could be useful.

Preference for mirror images and video image in Java sparrows (Padda oryzivora)

Java sparrows were exposed to a mirror and a frosted mirror, a mirror and a live bird, a mirror and a live bird with frosted screen, a closed circuit TV monitor and a TV program or the closed circuit monitor and an upside down monitor. The birds showed strong preference for the self-image on the mirror, the live bird and the self-image on the monitor. They preferred almost equally to the mirror and the frosted live bird. These results suggest that the Java sparrows saw the self-image on the mirror as conspecific image.