Monkey Monday | Oxytocin May Be The Secret To Strong Societies

In the first study that non-invasively measures oxytocin levels in wild animals, researchers have found that in chimpanzees this hormone likely plays a key role in maintaining social relations among both related and non-related animals. The bond goes beyond genetic ties – it could be the very glue that holds societies together.

Published Jan. 23, 2013, in Proceedings of the Royal Society, "Urinary oxytocin and social bonding in related and unrelated wild chimpanzees” reported findings resulting from an international collaboration of researchers from the United Kingdom, Uganda, Germany, the United States of America, and Switzerland.

Toni Ziegler, Ph.D., senior scientist and head of Assay Services at the Wisconsin National Primate Research Center, University of Wisconsin-Madison, conducted the team’s hormonal analyses for the past three years after researchers collected urine samples from a troop of chimpanzees in Uganda’s Budongo Forest. Urine was collected from plastic sheets or leaves following episodes of grooming among the animals, and then transferred with sterile pipettes into sample vials before shipping to the WNPRC for measuring and analysis.

Lead authors Catherine Crockford, Roman Wittig and colleagues at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, interpreted the data. They reported that oxytocin levels spiked after grooming among cooperating partners in contrast to non-cooperating partners or after no grooming, regardless of genetic relatedness or sexual interest. This suggests that, in chimpanzees, oxytocin plays a key role in maintaining social relations beyond genetic ties and in keeping track of social interactions with multiple individuals over time. Furthermore, the researchers found that when a chimp engages in grooming with another chimp, if there is no previously established friendship, oxytocin levels do not increase in either animal.

“We developed the assay methods used in this study for measuring urinary oxytocin in human children and nonhuman primates,” Ziegler said. “This is our first report of its role in social bonding in a totally wild primate. This technique will allow field researchers and human researchers alike the opportunity to learn about the importance of social bonding in primates.”

Wisconsin National Primate Research Center