“I Will Remember You…”
Hello! I hope you enjoy this blog about ape memories. - Katie
I should actually be asking if you remember me, it’s been a while since I’ve written a blog post! Perhaps it’s fitting that a new study on ape memories inspired me to share again. I think it’s a confluence of factors generating this inspiration… not the least of which is the time I recently spent with some of my favorite chimpanzees at Chimfunshi in Zambia.
Friends often ask if the chimps remember me when I visit. I’ve been traveling to and from Zambia since 2009 but at times years have passed between my visits to the chimps. I tell friends that I’m confident some chimpanzees do remember me. For example, Chiffon, who I’ve known through some of his most difficult and some of his most wonderful experiences, definitely does. Although the most exciting times for me are when the chimps don’t give me the time of day. I like to see them so wrapped up in being chimps that the people, like me, are scenery. That’s when my heart is really full. When they are patrolling their boundaries, wrestling, catching termites or building nests, that’s when I love to be there, watching, ignored.
Recently, researchers “asked” apes who they remembered by showing pictures.
Back to chimpanzee memories and the main point of this post. Colleagues of mine just published a beautiful study demonstrating that apes remember other apes they haven’t seen for decades. This isn’t so surprising given that apes can live into their 60s, have complex social relationships, and brains similar to ours. We remember (with a bit of prompting) people we knew decades ago. But this study provides beautiful evidence that other apes do as well.
The researchers studied chimpanzees and bonobos (another species of ape, equally closely related to us) living at Edinburgh Zoo in Scotland, Kumamoto Sanctuary in Japan, and Planckendael Zoo in Belgium. They measured how long the apes looked at pictures of apes they had known previously and pictures of apes who were strangers. When the apes sat in front of the screen (to drink some juice), researchers could measure their eye gaze without disturbing them using an infrared eye tracker positioned just below the computer screen.
Chimpanzees and bonobos looked longer at former groupmates than at strangers.
The results showed that apes looked longer at former groupmates than they did at strangers. They also looked longest at apes they hadn’t seen in a very long time, and there was some evidence that they looked longer at those with whom they had close relationships. These findings supported the researchers’ hypothesis that “bonobos and chimpanzees possess an enduring memory for previous social partners.”
Clearly the apes recognized something different in the photos of the familiar ape faces. Whether the faces of these apes triggered memories or emotions associated with those relationships remains to be studied, but something was sparked in those apes that kept their attention. The authors published the study open access, so you can read the details yourself (link below).
Two young chimpanzees at Chimfunshi Wildlife Orphanage in Zambia, likely to remember each other for years. Photo by K. Cronin.
Chimpanzees and bonobos… and me.
Just this morning, when dropping off my daughters at school, another parent stopped me. “Hey, I’ve been meaning to talk to you. I think we know each other, but I’m not sure from where.” We both paused on the sidewalk and looked at each other’s faces, much like the apes might have done in the study. I saw something familiar immediately, especially around her eyes. I looked for another second, and then I recognized her as the daughter of one of my high school teachers, and student who was a year older than me in school. I couldn’t think of her name without help, but her face was familiar and it drew me in, wanting to look more, wanting to fully unlock the memory. It wasn’t until I was already writing this post that I thought how relevant this morning’s event was. I could be another ape subject in a familiar face study.
Two questions for you, readers.
One: Are you surprised the apes remember? I am not, but I’m excited Laura Lewis and colleagues developed such a simple and straightforward way to “ask” the apes and demonstrate how similar their minds are to our own.
Two: Did the title of this blog also start Sarah MacLachlan playing in your head? (What about now?)
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Learn More
You can learn more about first author, Dr. Laura Lewis of University of California, Berkeley, here and the senior author, Dr. Chris Krupenye of Johns Hopkins University, here.
The study: Lewis LS, Wessling EG, Kano F, Stevens JMG, Call J & Krupenye C. 2023. Bonobos and chimpanzees remember familiar conspecifics for decades. PNAS. Link to article.
