Why use monkeys for biomedical research?

A report released by nine science advocacy groups on Aug. 24, 2016, highlights the essential role nonhuman primates play in finding treatments for serious and life-altering conditions such as Alzheimer’s disease, cancer, Zika virus, HIV/AIDS and Parkinson’s disease. Read more...

What is a primate?

A primate is the most general category of closely related, intelligent, visually oriented, dexterous mammals possessing hands instead of paws. Primates can be divided into humans, apes, monkeys and prosimians. These groups can be differentiated on the basis of physical features, for example, number of teeth, brain size relative to body size, overall body size, and presence or lack of a tail. After humans, the smartest and generally largest primates are the apes, e.g. chimpanzees and gorillas. Prosimians, e.g. lemurs, with the smallest relative brain and body size, are the most primitive primate. They are often active at night. back to top

What monkey is most used in research?

Rhesus monkeys, or Rhesus Macaques (Macaca mulatta) are most widely used in research. For information on all of the species used at the NPRCs, please see the Species page. back to top

Where do Rhesus monkeys come from?

Rhesus monkeys (Macaca mulatta) monkeys are native to Pakistan, India, Nepal and parts of Afghanistan, China and southeast Asia, where they are often found in urban areas. They can adapt to a wide range of climates. back to top

How long do Rhesus monkeys live?

In the wild, survival to old age is relatively rare due to disease, injury and predation. In the wild, a rhesus macaque’s life span can be up to about 18 years of age. In captivity, monkeys live longer. With excellent nutrition and medical care, Rhesus Macaques can live up to 38 years of age. back to top

When is a Rhesus monkey an adult?

Rhesus monkeys are capable of breeding at 3 - 4 years of age, but they do not become fully grown or socially mature for several years after that. back to top

What do Rhesus monkeys eat?

Monkey diets vary with species, the season and even by the sex of the animal. In the wild, rhesus monkeys thrive on fruits, seeds, roots, herbs and insects. In a year, a wild monkey may eat over 200 different things. In captivity, monkeys primarily eat monkey chow and an array of fresh fruits, vegetables, seeds and nuts. back to top

Why do some of the monkeys' faces sometimes look swollen?

Rhesus macaques have cheek pouches in which they store food until they find a spot in which to settle down and eat. Some animals appear to have distorted necks because their pouches are full of food! back to top

How smart are monkeys?

Intelligence is difficult to measure, and there are different aspects to intelligence even among humans. But monkeys have excellent memory, complex vocal systems and show sophisticated social strategies that rival those of any soap opera. Monkeys can be taught to use computers to solve problems using a touch-screen or joystick. This ability is one that makes them suitable subjects in studies on how the brain works and how to treat problems that affect the brain. back to top

How do monkeys live when they are in their natural social groups in the wild?

Most of the species form multi-male/multi-female groups in which there is a strong dominance hierarchy for both males and females. Group sizes vary widely but can contain several hundred individuals in some of the species, e.g. rhesus monkeys and squirrel monkeys. Kinship plays a critical role in the social structure. Social groups are composed of several matrilines or family groups. Each matriline consists of the dominant female, her daughters, granddaughters, and immature male offspring. Each animal has a rank within its matriline, and matrilines are ranked with respect to one another. A female is born into and grows up in the same group, her natal group. Males leave their natal social groups at maturity and may live solitarily or in all-male bachelor groups and remain in them for two or more years before trying to join a new social group as fully adult breeding males. back to top

Do monkeys form friendships? How do they show their friendships?

Monkeys form strong, friendly relationships that are manifested by grooming, by support in conflicts with other monkeys and by spending considerable time around each other during the day and by sleeping next to each other at night. Animals with close bonds often feed close to each other, while other animals will space out widely to avoid aggression. These relationships are often, but not always, found among kin. back to top

Do caretakers form a bond with the monkeys?

Yes, they do! And the bonds formed are good for the caretakers, for the monkeys, and for the science. A well-written book that looks at this issue in depth is "The Inevitable Bond: Examining Scientist-Animal Interactions", H. Davis and D. Balfour, 1992, New York: Cambridge University Press. back to top

Why use Rhesus monkeys?

Rhesus monkeys share about 93 percent of their genes with humans. As our closest relatives, monkeys can provide the most applicable information toward solving human health problems. Since most biomedical research on human diseases cannot be conducted on humans for ethical reasons, monkeys are essential for understanding disease processes and for testing the safety and efficacy of therapies.

Monkeys share many important features with humans. There are similarities in anatomy and physiology, reproduction, development, immunology, genetics, cognition, and social complexity. For example, Rhesus monkeys, unlike other mammalian species, have a menstrual cycle and hormonal patterns comparable to humans, which means they are necessary to study issues related to fertility, pregnancy, and changes that occur with menopause. Rhesus monkeys are also susceptible to an immunodeficiency virus similar to HIV, making them ideal for the study of AIDS and new vaccines and drug treatments. Since monkeys in breeding colonies can live well past their typical lifespan in the wild, they also provide opportunities for aging research, including studies on Alzheimer’s disease. Nonhuman primates have made significant contributions to the study of hepatitis, malaria, respiratory viral diseases, Parkinson’s disease, stem cell transplantation, and gene therapy.

In addition to biomedical research for advancement of human health, the NPRCs conduct research to help improve the physical health, psychological well-being and veterinary care of captive and wild monkeys.

For a listing of all areas of research at the NPRCs, please see the Areas of Research page. back to top

Is it possible to use computer models or cell cultures instead of animals?

The NPRCs follow the principles of “reduce, refine, replace.” Whenever possible, researchers must reduce the number of animals to the smallest number of animals necessary for a valid scientific result, refine how experiments are conducted by choosing procedures that minimize pain and distress, and replace animals with non-animal alternatives, such as computer models, cell cultures, or choosing a species lower on the phylogenetic tree (mice instead of monkeys). back to top

Why can’t you replace animals with cell cultures or computer simulations?

It is currently not possible to completely replace animal models with computer simulations or cell cultures. Technology can in some cases be used to reduce the number of animals necessary for a study. For example, noninvasive imaging, comparable to the imaging used in human medicine, minimizes the number of animals needed for a study by allowing long-term monitoring without the need for tissue collection. In addition, two types of stem cells (embryonic and induced pluripotent) produce human cells that are being used to test candidate drugs for toxicity. These stem cells are routinely used to produce human heart muscle cells and, because heart toxicity can be lethal, testing potential drugs in these tissues will save the lives of both animals and people.

Humans, like all animals, are extremely complicated. Many drugs are discovered because a chemical compound does something useful in a laboratory dish, but that discovery is followed by a long process of trial and error: first with simple animals, then with more advanced ones. Drugs often either fail to work or have unacceptable side effects, which are often discovered first through testing on animals. back to top

What steps are taken to ensure the research is conducted humanely?

All research is conducted humanely under strict compliance with the Animal Welfare Act, which governs laboratory animals’ housing, care and use in investigational studies. The law requires that any procedures causing more than slight or momentary discomfort be performed using appropriate pain-relieving drugs, and requires the use of anesthesia for surgical procedures, comparable to humans. It also stipulates that animals be euthanized during or after a procedure if they would otherwise endure chronic pain.

Studies require prior review and approval by an Institutional Animal Care and Use Committee (IACUC), which ensures that all research projects meet all federal laws governing animal care and use. Primate Center veterinarians and scientists are dedicated to ensuring that animals involved in research projects are provided with the best care and that research is conducted according to approved IACUC protocols. Veterinarians also provide routine health care, including regular physical exams and dental care.

All NPRCs are accredited by the Association for Assessment and Accreditation of Laboratory Animal Care International (AAALAC), a private, nonprofit group that promotes the humane treatment of animals in science.

For more information, please see the Animal Welfare page. back to top

Who regulates animal research?

Both federal and university bodies regulate research using vertebrate animals:

  • U.S. Department of Agriculture
  • Office of Laboratory Animal Welfare, National Institutes of Health
  • Food and Drug Administration
  • Institutional Animal Care and Use Committees

For more information, please see the Animal Welfare page. back to top

What is done for the psychological well-being of the nonhuman primates?

Each primate center has developed a plan for environmental enrichment and psychological well-being of their nonhuman primates to comply with revised Animal Welfare Act standards. It is a moral responsibility to make the lives of animals used in research as pleasant as possible, and it is also good research. To assure that research findings are as accurate and applicable as possible, monkeys need to be psychologically healthy.

For more information, please see the Animal Welfare page. back to top

How do we keep the monkeys happy?

We make every effort to house as many monkeys as possible in social groups. When monkeys must be housed alone for research or health reasons, extra friendly interaction with people is provided. We also provide for exercise and play, outlets for their curiosity, and activities to occupy their minds and hands. Examples include swings and perches, toys, varied food treats, opportunities to forage, and food puzzle devices.

For more information, please see the Animal Welfare page. back to top

What does SPF mean?

SPF means “specific pathogen free.” SPF monkeys are free of specified infectious agents, including herpes B virus, type D retrovirus, simian immunodeficiency virus (the monkey form of HIV) and simian T-lymphotropic virus. Not only can these pathogens interfere with research results, monkeys carrying them pose risks to researchers and animal care staff. Certain types of AIDS research, in particular, require SPF animals. back to top

Can the diseases being studied spread to the community?

Infectious diseases are carefully controlled and all personnel are appropriately trained to ensure containment of biohazards. PPE (personal protective equipment) is worn at all times when around the animals, to ensure protection for the humans and animals. Humans carry infectious viruses and bacteria that can be transmitted to the monkeys, therefore all personnel are screened annually and wear PPE to protect themselves and the monkeys. back to top

Do monkeys make good pets?

The practice of keeping monkeys as pets is inhumane to the animals and potentially dangerous to people. Monkeys are so highly intelligent, social and emotionally complex animals that their needs cannot be met easily by human owners. Keeping a monkey as a pet can result in permanent emotional and/or physical damage to the animal and in behaviors that are potentially dangerous to humans. Monkeys can also carry diseases that are fatal to humans. back to top

How can I learn more about monkeys?

In addition to books, the Internet is an excellent resource. One of the best places to start is the Primate Info Net. This site contains a wealth of information and numerous links to other websites. back to top