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AAAS Fellow Eduardo Fernández-Duque Studies Monkeys to Learn About Humans

headshot of Eduardo Fernández-Duque
AAAS Fellow Eduardo Fernández-Duque, Ph.D.

Growing up in Buenos Aires, Eduardo Fernández-Duque, Ph.D., loved the outdoors and watching animals. The AAAS Fellow, who maintains dual citizenship in Argentina and the United States, gets to follow both passions as a biological anthropologist, someone who tries understanding humans through the lens of science and the human condition with a focus on human biology, says Fernández-Duque.

When he’s not teaching on the topic at Yale University, Fernández-Duque spends his summers in the field primarily observing owl monkeys through the Owl Monkey Project that he launched in 1996. These monkeys live in the Gran Chaco region of Formosa, Argentina, and Fernández-Duque conducts his fieldwork in the 4,000-acre Mirikiná Reserve of the Guaycolec Ranch where the monkeys live. He and his partners watch the monkeys daily and record their findings as part of the research he conducts as faculty in Yale’s Anthropology Department.

Besides owl monkeys, Fernández-Duque also studies titi monkeys in the Ecuadorian Amazon to better understand male-female relationships, paternal care and pair bonding in both human and non-human primates. He originally found himself studying primates and analyzing titi monkeys for the Ph.D. he earned in animal behavior with a focus on primates at the University of California at Davis in 1996. In his work, Fernández-Duque connected their study with understanding humans and human evolution and questioning what makes males and females different.

“We try to understand why and how humans became the way they became,” Fernández-Duque explains. “Why is it that, in humans, males are usually larger than females? Why is it that in some societies fathers are very involved in the care of their young, but in others not so much? What can we learn from our relatives, the monkeys, in terms of our social organization, mating patterns, tendency to polygyny, tendency to monogamy, always, always with a caveat that we have culture, and the monkeys don’t?”

He studies monkeys as a window into the biology of humans, acknowledging that for humans, knowing the biology isn’t enough. You need to know the culture as well. The monkeys he studies form a pair bond, and the fathers are especially committed to taking care of their young with the mothers, something he notes is highly unusual among monkeys and mammals as a whole.

“We cannot easily picture a bull and a cow hanging together taking care of the calf, right?” he asks. “If we think about the cow and the calf, we don’t picture the bull there. In most mammals, you don’t picture the male as having a very close relationship to the young.”

His nearly three decades of studying these monkeys have shown him that you can tweak the biology of males to prime them to be affiliated with their young, something scientists also know about humans, he explains. In certain societies, there’s a range of how much men get involved in raising their children. Studies like Fernández-Duque’s have found that if you’re going to engage the father into establishing a relationship with its young, that has to be done early on, as in within the first few days after birth.

“If we wanted to translate some of our findings to actions that may have a positive effect in humans, I would say, ‘Well we definitely need to review our paternal leave policies,’” he says, noting that in Argentina fathers get two days of parental leave while mothers get three months. “We must have both mom and dad involved in our societies.”

Fernández-Duque's research also helps scientists understand human evolution. Paleoanthropologists may determine that the male fossils are bigger than the female ones, but the fossils don’t indicate what the males and females were doing to explain the difference in their sizes. Fernández-Duque’s work helps scientists speculate on what roles those males and females might have had in the past.

“We use our understanding of living non-human primates today to help us reconstruct the behavior of our early ancestors for which we only have bones, we don’t have behavior,” Fernández-Duque notes. “That’s another way in which we link the study of living primates with research on human evolution.”

In 2020, Fernández-Duque earned AAAS’ prestigious John P. McGovern Lecture Award in the Behavioral Sciences. The award recognizes outstanding behavioral scientists from around the world and he was honored for a lecture he delivered about fatherhood, which particularly resonates with Fernández-Duque who has three sons.

What keeps him going all these decades later is seeing the passion in his younger colleagues eager to take this work on. He works with post-doctoral fellows and graduate students, and his Owl Monkey Project has allowed him to train nearly 400 undergraduates from 24 countries over the years.

“I plan to be around for some time yet, but it’s not too early to start thinking about who is going to be taking the baton,” he says.