Study finds lethal aggression is natural in chimpanzees

September 18, 2014

In the 1970s, Jane Goodall’s reports of chimpanzee violence caught the attention of a global audience. Since then, many people have compared chimpanzee intergroup aggression to primitive warfare, and have argued that chimpanzee violence is an adaptive strategy that gives the perpetrators an edge.

Others have argued that lethal aggression is the consequence of human activities such as provisioning (artificial feeding) by researchers, or habitat destruction. A new study of the pattern of intergroup aggression in chimpanzees and their close relatives, bonobos (also called pygmy chimpanzees), finds that human impact isn’t the culprit. Ian Gilby in field with chimpanzees Download Full Image

“This study debunks the idea that lethal aggression among wild chimpanzees is an aberrant behavior caused by human disturbances, like artificial feeding or habitat loss,” says ASU anthropologist Ian Gilby, who is co-director of the long-term Gombe chimpanzee database for the Jane Goodall Institute Research Center and a coauthor on the results published Sept. 18 in the journal Nature.

The research project compiled data collected over five decades from 18 chimpanzee (Pan troglodytes) and four bonobo (Pan paniscus) communities.

This study represents the first effort to test the human impact versus adaptive strategies hypothesis, which views killing as an evolved tactic to increase access to territory, food, mates or other benefits. Analysis of 152 lethal attacks finds that it is clear that lethal aggression directed toward members of other groups is part of the natural behavioral repertoire of chimpanzees – sometimes chimpanzees kill each other, regardless of human impact. However, bonobos were not observed to kill other bonobos, whatever the level of human impact.

“Gombe is the longest running of wild chimpanzee study sites,” says Gilby, “and is critically important for addressing questions about the impact of ‘provisioning.’” The practice of provisioning was discontinued at Gombe many years ago due to risk of infecting chimpanzees with human diseases.

Concurrent with the published study in Nature, Joan Silk, an ASU scientist who studies primate behavioral ecology, evolution and sociality, wrote a companion piece, “The evolutionary roots of lethal conflict,” for the publication’s “News and Views” column.

In it, Silk points out that the debates about the origins and prevalence of human warfare may be echoed in the search for the answer to chimpanzee adaptation versus human disturbance question. In the article, she says that “perceptions of behavior of primates, particularly chimpanzees, are often distorted” so that “morally desirable features, such as empathy and altruism, have deep evolutionary roots, whereas undesirable features, such as group-level violence and sexual coercion, do not.”

The data, however, she says, show that “there are some circumstances in which the benefits of lethal aggression exceed the costs for chimpanzees, nothing more. Humans are not destined to be warlike because chimpanzees sometimes kill their neighbors.”

Newly arrived at ASU, Gilby, an assistant professor in the School of Human Evolution and Social Change, studies chimpanzee behavioral ecology at Gombe, focusing on male cooperation and social bonds. His close association with this iconic field site and his position as co-director of the long-term Gombe chimpanzee database will provide ASU students with new opportunities to study wild great apes. Silk is a professor in the School of Human Evolution and Social Change. Both Gilby and Silk are research affiliates with ASU’s Institute of Human Origins, a research center of the College of Liberal Arts and Sciences in the School of Human Evolution and Social Change.

Julie Russ

Assistant director, Institute of Human Origins


Mayo grant will advance ASU's development of device to aid diabetics

September 18, 2014

An award of $65,000 from Mayo Clinic in Arizona will help Arizona State University bioengineer Jeffrey La Belle continue development of a tear-based glucose meter designed to help people living with diabetes monitor their health.

The funding will enable La Belle’s research team to take the next step toward preparing for clinical trials of the device that can assess glucose levels by drawing tear fluid from the eyes. Current devices for measuring blood glucose levels require piercing the skin to draw blood samples. Jeffrey La Belle Download Full Image

La Belle is an assistant professor in the School of Biological and Health Systems Engineering. He’s been working on the tear glucose sensor for more than three years in collaboration with Curtis Cook, chair of endocrinology at Mayo Clinic-Scottsdale, and Dharmendra Patel, the clinic’s chair of ophthalmology.

The tears sensor project began with support from a Mayo Clinic seed grant in 2011. BioAccel, an Arizona nonprofit that works to bring emerging biomedical technologies to the marketplace, is also supporting development of the tear glucose sensor.

Clinical trials are to be conducted at Mayo Clinic. The project team will seek additional support from the National Institutes of Health and industry to fund the trials.

“We have to make something we can ensure will be safe and effective outside the lab, and that is ready for a manufacturer,” La Belle said.

About 29 million people – more than 9 percent of the population – in the United States have diabetes, according to the American Diabetes Association. The disease is one of leading causes of death in the country.

Monitoring and managing blood glucose (or blood sugar) levels helps people with diabetes control the symptoms of the disease.

The tear sensor has been attracting interest from medical professionals and industry. Progress reports on development of the device have been published in four research journals, and La Belle has made about 25 conference presentations on the device.

He has provided research experience to more than 20 ASU engineering undergraduates and graduate students through their assistance with lab work related to the project.

Joe Kullman

Science writer, Ira A. Fulton Schools of Engineering