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Chimpanzee Facial Expressions are Helping Researchers Understand Human Emotional Communication

March 23, 2007

Media Contacts

Emily Rios, 404-727-7732,; Lisa Newbern, 404-727-7709,

ATLANTA – Behavioral researchers led by Lisa Parr, PhD, director of the Yerkes National Primate Research Center Cognitive Testing Facility and Chimpanzee Core, have found understanding chimpanzee facial expressions requires more attention to detail than researchers initially thought. Correctly interpreting the subtleties within chimpanzees’ facial expressions may be key to understanding the evolution of human emotional communication. Parr will present this new data at the upcoming “Mind of the Chimpanzee” conference, an international multidisciplinary conference on chimpanzee cognition being held March 22-25 at the Lincoln Park Zoo in Chicago.

According to Parr, “This discovery is an important step to help researchers recognize facial movements and understand why they are important. While some expressions, such as a playful look, can be identified using a single feature, other expressions, such as when a chimp bares his teeth, require looking at numerous characteristics within the face, including the eyes and lips.” This is similar to what researchers see in human emotional expressions. “Sometimes it’s easy to read what people are feeling, but at other times, we have to look at multiple places on their faces. Ultimately, we want to better understand what people are feeling and expressing emotionally because it helps us empathize with one another,” Parr continued.

To facilitate her studies, Parr developed the Chimpanzee Facial Action Coding System (Chimp FACS) to directly compare documented expressions of humans and chimpanzees. Using Chimp FACS, the chimpanzees in the study observed anatomically correct 3D animations of chimpanzee facial expressions and then were asked to match the similar ones. “After the chimpanzees matched similar images, we separated individual features of the original animated expression, such as a raised brow, by frame and pieced the frames back together to create a variation of the original expression. The chimpanzees then were asked to match the new expression to the original one. This is how we determined when the chimpanzees were using a single feature or if they needed more than one feature to match the similar expressions,” said Sheila Sterk, a senior animal behavior management specialist on Parr’s team.

In addition to Parr, four other Yerkes researchers will give presentations at the conference. They are Sarah Brosnan, PhD (“Responses to inequity and prosocial behavior in chimpanzees”), Frans de Waal, PhD (“A social brain: Chimpanzees and the negotiation of social relationships”), William Hopkins, PhD (“Advanced imaging techniques and the study of gestures and tool-use in chimpanzees”) and Victoria Horner, PhD (“Cultural transmission in captive chimpanzees”). Also, 9 Yerkes researchers will have poster presentations. Their topics range from what influences learning in a social setting to enhancing positive reinforcement training techniques. Combined, these oral and poster presentations represent the comprehensive behavioral research taking place at the Yerkes Research Center.

For more than seven decades, the Yerkes National Primate Research Center, Emory University, has been dedicated to advancing science and to improving human health and well-being. Today, the center, as one of only eight National Institutes of Health–funded national primate research centers, provides specialized scientific resources, expertise and training opportunities. Recognized as a multidisciplinary research institute, the Yerkes Research Center is making landmark discoveries in the fields of microbiology and immunology, neuroscience, psychobiology and sensory-motor systems. Research programs are seeking ways to: develop vaccines for infectious and noninfectious diseases, such as AIDS, malaria and Alzheimer’s disease; treat cocaine addiction; interpret brain activity through imaging; increase understanding of progressive illnesses such as Parkinson’s and Alzheimer’s; unlock the secrets of memory; determine behavioral effects of hormone replacement therapy; address vision disorders; and advance knowledge about the evolutionary links between biology and behavior.

The Robert W. Woodruff Health Sciences Center of Emory University is an academic health science and service center focused on missions of teaching, research, health care and public service. Its components include the Emory University School of Medicine, Nell Hodgson Woodruff School of Nursing, and Rollins School of Public Health; Yerkes National Primate Research Center; Winship Cancer Institute of Emory University; and Emory Healthcare, the largest, most comprehensive health system in Georgia. Emory Healthcare includes: The Emory Clinic, Emory-Children's Center, Emory University Hospital, Emory University Hospital Midtown, Wesley Woods Center, and Emory University Orthopaedics & Spine Hospital. The Woodruff Health Sciences Center has a $2.5 billion budget, 17,600 employees, 2,500 full-time and 1,500 affiliated faculty, 4,700 students and trainees, and a $5.7 billion economic impact on metro Atlanta.

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