In a study published in eLife, an international collaboration of researchers including Dora Biro, the Beverly Petterson Bishop and Charles W. Bishop Professor of Brain and Cognitive Sciences at the University of Rochester reports that aging chimpanzees may mirror humans in experiencing age-related declines in their ability to perform cognitively challenging tasks. The research offers clues to the origins of Alzheimer’s disease and other cognitive disorders, and what these patterns reveal about human brain aging.

“Our work is a mixture of trying to understand chimpanzee cognition in its own right and then trying to see what that tells us about the evolution of our own minds,” Biro says. “Getting these comparative data points between us and our non-human primate relatives can be really valuable for reconstructing evolutionary histories, whether it be anatomical, behavioral, or cognitive.”

The behavioral changes that occur with aging have been widely studied in humans and captive primates, but scientists know little about how growing older affects apes in the wild, in part because surviving to advanced age is rare in natural habitats. For those that do survive, tracing their long-term behavior changes including the use of tools can yield fundamental insights.

“Tool use is uncommon among animals, possibly because it requires a suite of physical and cognitive abilities, such as planning, fine motor coordination, understanding causal relationships, and identifying physical properties of objects in the environment. Given many of these faculties can be impacted by aging, wild animals’ tool-use behaviours could be vulnerable to decline with old age,” says lead author Elliot Howard-Spink, a postdoctoral researcher at the Max Planck Institute of Animal Behavior, and Biro’s former PhD student at the University of Oxford.

“Until now, there has been no systematic study of how old age influences the technological behaviors of wild animals, likely due to a lack of long-term data,” adds Howard-Spink.

Aging in the Wild
Biro and her team analyzed decades of footage of wild chimpanzees in Guinea’s Bossou forest to understand how aging impacts behavior and cognition. This community, studied since the 1970s, has dwindled from around 20 to just four members due to habitat loss and disease. Researchers observed that chimpanzees here exhibit one of the most complex tool-use behaviors nut cracking a learned skill that takes years to master through practice and observation.

Decline in Skill with Age
Upon returning to the field site after several years, Biro and her colleague noticed that an older female chimp, once an expert nutcracker, now struggled with tasks she had long mastered. She switched stones frequently, misaligned nuts, and took longer to complete actions. Other elderly chimps showed similar signs of cognitive decline. Since the Bossou group lives safely into their 50s and 60s protected by local communities they offer a rare opportunity to study natural aging in the wild.

Evolutionary Insights
These observations provide valuable clues about human evolution. Because humans and chimpanzees share a common ancestor, studying aging chimps helps reveal whether cognitive decline and dementia-like symptoms existed before humans evolved. If so, the roots of conditions like Alzheimer’s may lie deeper in our evolutionary past, offering insight into the biology of aging and brain health.

Cognition across the lifespan
Tracking how older chimps perform complex tasks such as nut cracking highlights how aging affects memory, coordination, and problem-solving. Biro suggests that early skill development and continuous practice throughout life may influence how well such abilities are maintained in later years, deepening our understanding of cognitive aging across species.

Source: https://www.rochester.edu/newscenter/aging-wild-chimpanzees-tool-use-cognitive-decline-674942/