Anthropologists for the first time have captured on video wild chimpanzee mothers teaching their offspring to use tools to find food. The videos were made at termite mounds in the Nouabalé-Ndoki National Park in the Republic of Congo.
“Wild chimpanzees are exceptional tool users, but in contrast to humans, there has been little evidence to date that adult chimpanzees teach youngsters tool skills,” says first author Stephanie Musgrave, an anthropology graduate student at Washington University in St. Louis. “We found that mother chimpanzees in the Goualougo Triangle teach by transferring termite-fishing probes to their offspring.”
“Tool transfers are costly for mothers … but are beneficial for offspring, who gain increased opportunity to learn tool skills and gather termites.”
“In this population, chimpanzees select specific herb species to make their fishing probes, and they produce probes that have a particular brush-tipped design. By sharing tools, mothers may teach their offspring the appropriate material and form for manufacturing fishing probes.”
“It is easy for us to take for granted the importance of sharing information to learn complex skills, as it is ubiquitous in humans,” says coauthor Crickette Sanz, associate professor of biological anthropology. “Our research shows that the evolutionary origins of this behavior are likely rooted in contexts where particular skills are too challenging for an individual to invent on their own.”
Researchers used video to capture examples of wild chimpanzee mothers transferring specialized termite-gathering tools to less-skilled, immature chimpanzees. These transfers, which are costly to tool donors but beneficial to tool recipients, meet the scientific criteria for teaching in wild apes.
“Tool transfers are costly for mothers, whose ability to forage for termites is reduced, but are beneficial for offspring, who gain increased opportunity to learn tool skills and gather termites,” Musgrave says. “This is the first such evidence satisfying these criteria for teaching in wild apes.
“Identifying teaching among wild animals is difficult because one has to quantify the impact of possible teaching behaviors on both the teacher and the learner. “Using video footage from remote camera traps placed at termite nests in the chimpanzees’ home range, we were able to observe and quantify how sharing tools affected those who relinquished their tools as well as those who received them.”
Split the stick
Chimpanzees are exceptional among animals for their remarkable propensity to make and use tools. Since different groups of chimpanzees use different types of tools, the teaching process also may need to be customized to address local conditions.
“Studying how young chimpanzees learn the tool skills particular to their group helps us to understand the evolutionary origins of culture and technology and to clarify how human cultural abilities are similar to or different from those of our closest living relatives,” Musgrave says.
The findings, published in Scientific Reports, have interesting implications for identifying the cognitive underpinnings of teaching. In humans, teaching involves an understanding of others’ abilities and the intention to help them learn. In this study, chimpanzee mothers both anticipated the youngsters’ need for a tool and devised strategies to reduce the effort necessary to provide them.
In examples captured in the videos, mothers sometimes bring multiple tools to a termite nest; they may also divide their fishing probe in half lengthwise, giving one-half to their offspring and keeping the other half. This strategy provides their offspring with a usable tool without compromising their own ability to gather food, Musgrave says.
Remote video technology “is a very effective means of monitoring wildlife without increasing human impact, Sanz says. “Our camera array also provides a means of monitoring the health of the forest, as other endangered species such as western lowland gorillas, forest elephants, and leopards are ‘captured’ on film.
“In addition to our traditional tracking of wild chimpanzees through the forest each day, this remote video technology has been a force multiplier in expanding the scope of our research to several other chimpanzee communities. We have observed a generation of chimpanzee kids learn how to use these tool sets, without having to spend a decade habituating them to human presence or risk exposing them to anthropogenic diseases.”
Researchers from the Wildlife Conservation Society, the Lincoln Park Zoo, the Max Planck Institute, and Franklin and and Marshall College.