Two recent studies from the Max Planck Institute for Evolutionary Anthropology in Germany are allowing scientists to see further into how chimpanzees view the world.
The photos show chimpanzee Pan wearing an eye-tracking system on her head (A) and also a picture from the outward-facing camera on her headset (B). The cross mark in the lower-right corner shows where Pan’s gaze is directed.
In the first one, scientists have been trying to determine how chimpanzees visualize the world by using camera’s attached to goggles – in essence, the scientists want to “chimpan-see.”
“If we know the differences between chimpanzees and humans, we will have an insight into how human perception has evolved,” said comparative psychologist Fumihiro Kano. “Everybody wants to see the world through chimpanzee eyes, right? That’s one of my childhood dreams. How do chimpanzees, the closest relatives of humans, see the world?”
To accomplish this, the scientists used specially designed goggles with two cameras attached to separately monitor each eye, one pointing at the right eye and the other pointing outward.
“We modified the eye-tracker goggle shape so that the chimpanzee could wear it and like it,” Dr. Kano said. “If the chimpanzee felt uncomfortable wearing the goggles, she wouldn’t care about throwing it away!”
The researchers had Pan, a female chimpanzee living at the Institute, wear the goggles while performing tasks she already knew. They found that she altered her “gaze” depending on whom she was meeting and her familiarity with the experiment.
Stephen Shepherd of Rockefeller University, who was not a member of the research team, told Inside Science, “This work builds toward an understanding not just of how chimpanzees learn about the world, but how they want to influence it. We can use gaze as a readout of what chimpanzees think is important to attend and affect.”
Dr. Shepherd added that this work would help to better understand the evolutionary continuum between chimpanzees and humans. “It will be very interesting to see how humans, chimpanzees and other primates use gaze while performing the same real-world tasks,” he said. “I would love to know if chimpanzees are intermediate between humans and monkeys, or if they’re just like humans.”
In the second study, other researchers from the Max Planck Institute have been discovering that chimpanzees’ opposable thumbs are “green.” At the Tai National Park in Cote d’Ivoire, West Africa, they’ve been learning the methods the animals use to search trees for fruit. The researchers showed that the chimpanzees were able to predict which trees bore ripe fruit.
By analyzing recordings of the “mistake” trees – trees that had no fruit – the scientists showed that the chimpanzees employed knowledge beyond sensory clues to find fruit and actually had expectations of finding fruit-filled trees days in advance. The scientists’ even reasoned that the chimpanzees know that the same species of trees ripen at the same time.
“They did not simply develop a ‘taste’ for specific fruit on which they had fed frequently,” said Karline Janmaat to ZeeNews.com. “Instead, inspection probability was predicted by a particular botanical feature – the level of synchrony in fruit production of the species of encountered trees.”
The scientists found that the chimpanzees were able to categorize trees and distinguish what trees were in season by tasting ripe fruit and then using this knowledge, combined with past knowledge of “mistakes,” to increase their success rate in finding food.
“Our results provide new insights into the variety of food-finding strategies employed by our close relatives, the chimpanzees, and may well elucidate the evolutionary origins of categorization abilities and abstract thinking in humans,” said Christophe Boesch, director of the Max Planck Institute.
Note: The Nonhuman Rights Project does not endorse experimentation on captive animals. However, we do quote the results of these experiments when they help make the case that the animals have a level of sentience, self-awareness, and, in some cases, a theory of mind that demonstrates that we should not keep them in captivity in the first place.