Let’s break down the story of Robert Yerkes—the good, the bad, and the deeply problematic.
1. From Farm Life to Harvard: Yerkes’ Early Days
Robert Yerkes’ story starts in the Pennsylvania countryside, where he was born in 1876. Growing up in a farming family, he was no stranger to early mornings, hard labor, and the kind of life that demanded physical endurance. But Yerkes? He wasn’t built for the fields. His mind was wired for curiosity, and he had no intention of spending his life behind a plow. He set his sights on medicine, dreaming of a future as a doctor—something far removed from the dirt roads and manual labor of his childhood.
The problem? Higher education wasn’t exactly cheap, and his family didn’t have the money to send him off to college. Luckily, a generous uncle stepped in to help, allowing him to enroll at Ursinus College in 1892. This financial support wasn’t just a lifeline—it was Yerkes’ ticket out of rural life and into the world of academia.
Fast-forward to 1897, and he had a big decision to make: stick with his original plan of attending medical school in Philadelphia, or accept an offer from Harvard to study biology. Harvard had that Ivy League shine, and it wasn’t just any school—it was a place where groundbreaking research happened. So, Yerkes made the leap.
But here’s the plot twist: once he got to Harvard, he realized he was way more into studying animal behavior than human medicine. The more he explored psychology, the more fascinated he became with how animals think, learn, and adapt. His curiosity completely took over, and suddenly, the dream of being a doctor started fading into the background. By the time he earned his Ph.D. in 1902, Yerkes had fully committed to psychology—specifically, comparative psychology, a field that examines how different species think and behave.
So, just like that, his life’s path shifted from stethoscopes and surgeries to lab experiments and research papers. And honestly? It was a move that would shape the rest of his career.
2. Climbing the Academic Ladder: Harvard and Beyond
After locking down his Ph.D., Yerkes stuck around at Harvard, scoring a gig as an instructor and later an assistant professor. But here’s the thing—being a young academic wasn’t exactly a fast track to financial stability. Harvard’s paycheck wasn’t cutting it, so Yerkes had to hustle. To keep himself afloat, he picked up extra jobs, including teaching psychology at Radcliffe College and diving into research at the Boston Psychopathic Hospital. It wasn’t glamorous, but it paid the bills and gave him more hands-on experience in psychology.
In 1907, Yerkes made his first big move in the field by publishing The Dancing Mouse, a book that explored animal behavior and experimental psychology. This wasn’t just some random pet project—it was a stepping stone that helped him build credibility as a researcher. His work showed that studying animals could give real insights into behavior, which wasn’t a mainstream idea at the time.
During these early years, Yerkes crossed paths with some major players in psychology. One of his closest intellectual allies was John B. Watson, who would go on to pioneer behaviorism. They bounced ideas off each other, and while their approaches weren’t identical, they both believed in studying observable behavior rather than just theoretical concepts.
But while Yerkes was making academic strides, money—or the lack of it—was always in the background. His financial struggles shaped a lot of his decisions, pushing him toward opportunities that could offer more stability. His career was taking off, but he still had a long way to go before he found the security and recognition he was chasing.
3. The Intelligence Testing Era: Yerkes and the Army Alpha & Beta Tests
World War I didn’t just reshape global politics—it also gave psychology a new purpose. And Robert Yerkes? He was right at the center of it. In 1917, as president of the American Psychological Association (APA), he saw an opportunity to bring psychology into military decision-making. His big idea? Large-scale intelligence testing for U.S. Army recruits.
Enter the Army Alpha and Beta tests—psychology’s first attempt at mass intelligence assessment. The Alpha test was verbal, designed for literate soldiers, while the Beta test was nonverbal, meant for those who couldn’t read. In theory, this was a game-changer. Over a million recruits were tested, and for the first time, intelligence was being “measured” on a national scale.
But here’s the catch: these tests weren’t as scientific or fair as Yerkes claimed. The questions were heavily biased toward American culture and middle-class experiences. Take this gem from the Alpha test: “Velvet Joe appears in advertisements of… (tooth powder) (dry goods) (tobacco) (soap).” If you weren’t already familiar with American ads, good luck getting that one right.
The results? They showed that recent immigrants from Southern and Eastern Europe scored significantly lower than older immigrant groups from Northern and Western Europe. At the time, Yerkes and his supporters framed this as proof of inherent intelligence differences between racial and ethnic groups. But looking back, it’s clear these tests weren’t measuring intelligence—they were measuring exposure to American culture and language.
Unfortunately, these flawed results had real consequences. They reinforced anti-immigrant sentiment, helped fuel xenophobic policies, and were even used to justify restrictive immigration laws in the 1920s. What Yerkes saw as a major contribution to psychology also became one of his most controversial legacies—one that continues to serve as a cautionary tale about bias in intelligence testing.
4. Yerkes and Eugenics: A Dark Chapter
Now, here’s where things get really messy. Yerkes wasn’t just a psychologist—he was also a firm believer in eugenics, the now-debunked and deeply racist idea that humanity could be “improved” by controlling reproduction and promoting so-called “superior” genetic traits. And unfortunately, he didn’t just support eugenics from the sidelines—he actively used his work in intelligence testing to push for policies that discriminated against entire racial and ethnic groups.
Using data from his Army Alpha and Beta tests, Yerkes argued that some populations—specifically immigrants from Southern and Eastern Europe—were naturally less intelligent than others. His findings, of course, ignored the fact that intelligence scores were heavily influenced by education, cultural exposure, and language barriers. But in the early 20th century, this kind of pseudoscience wasn’t just accepted—it was welcomed by policymakers looking for “scientific” justification for racist immigration restrictions.
Yerkes’ influence reached the highest levels of government. As an “Expert Eugenic Agent” (yes, that was an actual title) for the U.S. House Committee on Immigration and Naturalization, he played a role in shaping the National Origins Formula—a system that drastically cut immigration from regions he and other eugenicists deemed “less desirable.” On top of that, he was deeply involved with the Eugenics Record Office, an organization obsessed with tracking and promoting racial purity.
Looking back, Yerkes’ involvement in eugenics is one of the most troubling aspects of his legacy. Modern psychology has completely discredited the racist theories he helped spread, and today, we understand that intelligence is shaped by a wide range of factors—education, socioeconomic status, environment—not just genetics. But in Yerkes’ time, these biases largely went unchecked, and the policies he influenced had real, harmful consequences that lasted for generations.
It’s a stark reminder of how scientific research can be twisted to serve dangerous ideologies, and why psychology (and science in general) must always be questioned, refined, and held accountable for its ethical implications.
5. The Shift to Primatology: Chimpanzees Take Center Stage
After years of making a name for himself in intelligence testing (and stirring up plenty of controversy along the way), Yerkes switched gears in the 1920s. Instead of measuring human intelligence, he became obsessed with primates—particularly chimpanzees—and their cognitive abilities. It was a major pivot, but one that would shape the rest of his career.
And when I say obsessed, I mean obsessed. Yerkes didn’t just study chimps from a distance—he literally brought them into his home. He bought two chimpanzees, Chim and Panzee, and set up what can only be described as a bizarre experiment in primate domestication. He had them eating meals at a miniature dining table, using forks, and interacting with humans in ways that, at the time, were groundbreaking. Today, it sounds like something out of a weird science documentary, but back then, it was part of Yerkes’ deep dive into primate psychology.
His fascination took him to Cuba, where he studied Rosalía Abreu’s famous primate colony. Abreu was a trailblazer—she was the first person to successfully breed chimpanzees in captivity. Yerkes took detailed notes on her methods, learning how to raise and study chimps outside of the wild. Inspired, he decided he needed his own dedicated research facility.
By 1924, he locked down a position as a professor of psychobiology at Yale (a title he basically pioneered) and secured funding from the Rockefeller Foundation to take his primate studies to the next level. He founded the Yale University Laboratories of Primate Biology in New Haven and later established the Anthropoid Breeding and Experiment Station in Florida. These centers were game-changers—they laid the groundwork for modern primatology and set the stage for primate research in psychology, biology, and medicine.
One of the most unique outcomes of Yerkes’ work was the development of Yerkish, a symbolic language designed to help primates communicate. While it didn’t exactly turn chimps into chatty conversationalists, it paved the way for future studies on primate cognition and the evolution of language.
His work in primatology was, without a doubt, his most lasting contribution to psychology. Unlike his intelligence testing and eugenics-driven research, which aged terribly, his studies on primate behavior, cognition, and social structures remain influential today. It was a strange, ambitious, and sometimes ethically questionable chapter of his career—but it’s also what cemented his place in the history of animal psychology.
6. Legacy: The Name That Was (and Wasn’t) Built to Last
By the time Robert Yerkes retired in 1942, his name was firmly attached to two very different legacies. On one hand, he had pushed psychology forward with his pioneering work in primatology. On the other, his involvement in eugenics and biased intelligence testing had left a stain that wouldn’t be ignored forever.
After his death in 1956, his research center was relocated to Emory University in Atlanta, where it became the Yerkes National Primate Research Center. For decades, his name remained linked to primate studies—one of the few aspects of his work that aged well.
But history has a way of catching up. By the 21st century, the scientific community had long since acknowledged the damage caused by eugenics, and Yerkes’ role in promoting racist policies was impossible to overlook. In 2022, Emory University made a big decision: they removed his name from the center. The facility is now called the Emory National Primate Research Center, reflecting a shift in how institutions recognize the ethical weight of history.
It’s a move that speaks volumes. While Yerkes’ contributions to primatology still matter, his legacy is no longer celebrated without acknowledging the harm his work also caused. Science evolves, but so does accountability—and this renaming was a clear signal that some names just don’t belong on the front door anymore.
7. Final Thoughts: A Complicated Legacy
Robert Yerkes was a giant in psychology, but his legacy is messy. On one hand, he helped shape the field of primatology, introduced large-scale intelligence testing, and influenced comparative psychology. On the other, his intelligence tests were racially biased, and his advocacy for eugenics contributed to harmful policies that marginalized immigrants and reinforced racist ideologies.
His work on primates continues to influence modern psychology and animal behavior research, but his role in intelligence testing and eugenics serves as a cautionary tale. Science isn’t just about discovery—it’s about ethics, responsibility, and how research impacts society.
Yerkes made history, but not all of it is worth celebrating.
