Orangutans are unique among great apes in their maturation process. As male orangutans experience puberty, specialized facial structures called "cheek pads" emerge, signaling sexual maturity. For most males, this occurs around 10 to 12 years of age, but maturity in orangutans housed with or near other adult males can be suppressed. When this suppression occurs, the development of these cheeks pads is delayed for up to 10 years, and the animal remains in a sub-adult state. The precise mechanisms of this suppression are not fully understood.
Dr. Melissa Thompson of the University of Mexico is working with Dr. Cheryl Knott of Boston University to better characterize orangutan development both in captivity and in their natural ranges. Seneca Park Zoo contributes to this project through collection of urine samples from our male orangutan Denda. Zoo keepers have trained Denda to urinate in a collection cup in exchange for a food reward. These urine samples are then sent to Dr. Thompson who analyzes the urine for concentrations of sex hormones, especially testosterone, to track the influences these hormones have on development. Zoo keepers also track Denda's development so that researchers will possibly be able to correlate hormonal changes with development in male orangutans.
For more information on Dr. Knott's research with both captive and wild orangutans, click here.