Chimpanzees are humankind’s closest living relatives. In the wild, these intelligent and resourceful great apes lead rich and complex social and emotional lives, and use a wide range of tools for a variety of purposes. Their strong similarities with humans have historically made them attractive research subjects. Today, much chimpanzee research has ended, but hundreds of chimps nonetheless continue to languish in laboratories.
About Chimpanzees
As adults, chimpanzees range in height from 3-1/4 to 5-1/2 feet when standing upright on two legs. Females average about 175 pounds in weight; males weigh about 200 pounds. Their arms are longer than their legs, enabling them to walk comfortably on all fours. Chimps eat a wide variety of food, including fruits, leaves, seeds, stems, bark, honey, buds, and blossoms, as well as ants, termites, and some small animals.
Like human infants, chimpanzee babies are totally dependent on their mother’s care for survival. Youngsters remain with their mothers for 5 to 7 years, often helping care for younger siblings. Both in the wild and in captivity, chimpanzees can live to age 50 or 60. In the wild, they move about in social groups called “troops” ranging in size from a few individuals to over 100 at a time.
Research has documented a wide range of tool use by chimps for a variety of purposes. For example, they will peel leaves off of a twig, then stick the twig down into termite nests to “fish” for insects. Many also use leaves to clean their fur, which covers most of their body, aside from their faces, as well as their palms and soles of their feet. Some chimps also use medicinal plants to treat themselves and others for illness and injury. These tools are a significant marker of their intelligence and likeness to humans.
Chimpanzees also have rich emotional and social lives. They appear able to experience the wide range of emotions that we usually associate only with the human species, including anger, jealousy, sorrow, and love. Like humans, chimpanzees maintain bonds that last for a lifetime, and do so not only with other chimpanzees, but also with humans. A story documented by the public television show, Nature, depicted a reunion between a 32-year-old chimp named Swing and the caretaker who had looked after him for five years in a hepatitis research lab 19 years before. The caretaker described the reunion as a very powerful moment for both of them, “full of hugs, tears, and grins.”
In the wild, chimpanzees live in tropical forests or mixed savanna in equatorial Africa. Their habitat is dwindling, as rain forests are cleared to build farms and villages. Due to a lack of survey data in several regions, it is difficult to know exactly how many chimps remain in the wild. Estimates range from 170,000-300,000, in populations fragmented by human development.
While chimpanzees are listed as an endangered species under the Convention on International Trade in Endangered Species (CITES), they are still illegally hunted for food and captured for the pet trade, for entertainment, and for research in some countries.
Chimpanzees in Research
News update. In November, 2023, the National Institutes of Health announced that 23 federally-owned chimpanzees would at long last be retired from Alamogordo Primate Facility, a federally-owned laboratory in New Mexico, to Chimp Haven sanctuary in Louisiana. Chimp Haven sits on 200 forested acres of forested land and serves as the national chimpanzee sanctuary. The Alamogordo chimps going there range in age from 34 to 62 years old and they will join around 200 federally-owned chimpanzees that have already been retired to Chimp Haven.
A long time coming, the move had been delayed for years because of concerns about the chimpanzee’s fragile health conditions under the stresses of the relocation. However, anticipated staffing shortages at Alamogordo prompted officials and caretakers to reassess the equation, leading them to ultimately decide that it would be in the chimps’ best interests to move to Chimp Haven. After years of research, these individuals will be able to live out the rest of their days in a safe, secure and comfortable sanctuary. (Following is a detailed history of the use of chimpanzees in research in the United States.)
In the U.S. during the 1920s, chimpanzees were first used for medical and behavioral research. In the 1950s, the US Air Force and NASA captured 65 wild chimpanzees from Africa for use in early space research and testing. In the mid-1980s to the mid-1990s, focus shifted away from space research and toward NIH-funded biomedical studies. For example, the National Institutes of Health (NIH) invested millions of dollars on a captive chimpanzee breeding program in order to create a pool of chimpanzees to be used for HIV and AIDS research. However, chimps proved to be poor HIV models. While they carry the virus, they do not become sick from it. Also, as in humans, it can take a decade to develop the disease, rendering chimps an expensive and time-consuming research model. Chimpanzees were also used for studies of many other diseases and conditions.
Decades went by of chimpanzees being used in cruel and painful studies, but finally, in the late 1990s, norms and policies began to shift in a positive direction. In 1997, a National Research Council (NRC) advisory committee recommended to the federal government that it stop breeding chimpanzees and that it work with private funding sources to establish sanctuaries for the “retirement” of research chimps. Peter Theran, VMD, director of the former Center for Laboratory Animal Welfare, an affiliate of the Massachusetts Society for the Prevention of Cruelty to Animals, served as the animal welfare representative on this advisory committee.
Also in 1997, the U.S. Air Force announced that it would no longer conduct biomedical research on chimpanzees. The following year, in 1998, the Air Force gave their chimpanzees to The Coulston Foundation (TCF) in Alamogordo, New Mexico, a private breeding and research facility. Around 650 chimpanzees were kept as research subjects at TCF and were used in studies on the spinal cord, Alzheimer’s disease, diabetes, and arthritis.
In December 2000, President Bill Clinton signed the landmark Chimpanzee Health Improvement, Maintenance, and Protection (CHIMP) Act into law. This legislation provided federal funding to establish a chimpanzee sanctuary system* so that these former research animals could live out their lives in social groups in an environment similar to their native African habitat. In 2007, the act was amended to prohibit returning retired chimps to laboratories, and in 2013, the CHIMP Act’s original $30 million spending cap was lifted.
An example of one such federally funded chimpanzee sanctuary is Chimp Haven, located in Louisiana on 200 acres of lush, forested land. The sanctuary provides permanent, enriched housing for retired research chimpanzees, as well as those no longer used for entertainment or as pets. The chimps live in complex indoor/outdoor environments and are cared for as the intelligent, social, emotional beings that they are.
In 2002, The Coulston Foundation was finally ordered to close after having accumulated a long history of Animal Welfare Act (AWA) violations, including inadequate housing and veterinary care, poor record keeping, and the unnecessary deaths of a dozen chimpanzees. From roughly 2002 until 2011, nearly all of TCF’s hundreds of chimpanzees were retired to Save the Chimps, a large privately funded chimpanzee sanctuary in Florida, in what would later be called the “Great Chimpanzee Migration.” Today, all have been moved to sanctuaries except for 85 individuals deemed by the NIH too sick or weak. Some of these NIH assessments are under litigation in court, however, as animal welfare advocates push for all chimpanzees, even those who are “weak” or “sick,” to have an opportunity to retire to a sanctuary. (This interactive map is a useful tool for seeing where and in what numbers captive chimpanzees remain in the United States.)
More forward steps were made in 2015, the Food and Drug Administration (FDA) announced that it would no longer support biomedical research on chimpanzees and began the process of “retiring” chimpanzees to sanctuaries such as Chimp Haven. Also in 2015, captive chimpanzees—not just wild chimpanzees—were at long last classified as endangered.
While much progress has been made in protecting humankind’s closest cousins, much remains to be done, as more than 200 chimpanzees remain in captivity, both in private research laboratories and in government-supported facilities.
* Note: There are many reasons that captive chimpanzees cannot be released back into the wild, the primary reason being a lack of available habit in their native lands. Even if sufficient habitat did exist however, captive chimps released near wild chimpanzee communities would be attacked as intruders, and captive chimps also lack the survival skills they would need in the wild. Many captive chimps are also infected with diseases that require specialized care.
