The recent escape of 43 rhesus macaque monkeys from a medical research facility in South Carolina has drawn significant attention to these animals, which are among the most extensively researched in the world. For over a century, these primates have served as a biological mirror for humans, illuminating both our strengths and weaknesses through their behaviors, organ systems, and genetic make-up.

Known for their expressive faces, these monkeys have been subjected to various studies, including those focused on vaccines, organ transplants, and the effects of maternal separation on infants. While animal rights advocates highlight the ethical concerns surrounding their use in research, many scientists argue that such studies are crucial for advancing medical knowledge and combating diseases like AIDS, polio, and COVID-19.

A notable scarcity of rhesus macaques occurred in 2003, causing research delays and prompting scientists to pay exorbitant amounts—up to $10,000 each—to secure these primates for their studies. The significant reliance on this species for research is well-established, with claims suggesting that virtually every major research university in the U.S. houses some rhesus macaques, often kept away from public view.

Dario Maestripieri, a behavioral scientist at the University of Chicago, has documented this reliance, noting that even institutions like NASA and the U.S. Army utilize rhesus macaques in varied research projects, including efforts to train them in playing video games for aeronautical simulations.

Rhesus macaques have been part of scientific studies since the late 19th century, coinciding with the growing acceptance of evolutionary theories. The first academic work on this species surfaced in 1893, addressing aspects of advanced pregnancy anatomy. By the mid-1920s, a breeding program was established at the Carnegie Science Institute to facilitate studies on embryology and fertility due to the species’ genetic closeness to humans.

Their popularity in research is due to their plentiful population and resilience. Rhesus macaques boast the broadest natural range of any non-human primate, found throughout regions from Afghanistan to Vietnam and China. Eve Cooper, a biology professor at the University of Colorado-Boulder, pointed out that these monkeys can thrive in a variety of environments, making their care and breeding more manageable.

In the 1950s, their kidneys played a pivotal role in the development of the Salk polio vaccine, and they were also integral to NASA’s endeavors during the space race. For instance, a rhesus monkey named “Miss Sam” was launched into space in 1960, reaching impressive speeds and altitudes before being safely retrieved and returned to her colony.

In 2007, the rhesus macaque’s DNA was sequenced, revealing a noteworthy similarity of approximately 93% to that of humans. This discovery emerged following the completion of the human genome project in 2001, which stimulated further genetic research on various animals, including this primate, making it the third primate species to have its genome decoded.

Further studies into the social behaviors of rhesus macaques reveal intriguing parallels to human interactions. Maestripieri notes that these monkeys exhibit family-oriented behavior and often align themselves with relatives during conflicts but will also seek out allies when under threat. “They’re very political,” he emphasizes, drawing a parallel between their social maneuverings and human political dynamics.

Maestripieri has contributed his expertise to a reality TV series featuring rhesus macaques in India, called “Monkey Thieves.” He notes that following the lives and stories of these creatures is highly engaging as they frequently display behaviors reminiscent of human societal structures.