About 1,400 monkeys live at the Poolesville facility, where scientists study their social behaviors, looking for the keys to human disorders such as autism. Photos by Hilary Schwab

Twenty-five miles northwest of Bethesda, the roads become narrow and winding as they traverse the rolling farmland outside Poolesville. Eventually a left turn leads to a 513-acre farm with a white barn. It looks like any other farm, but the sign at the entrance to a long driveway tells otherwise.

This is the National Institutes of Health Animal Center, where a guard booth blocks unauthorized entry onto the property.

The facility—NIH’s only dedicated animal research center—is little known outside tiny Poolesville, but it plays a key role in supporting research aimed at unlocking the mysteries behind human and animal diseases and disorders.

The agency and its researchers don’t publicize the facility’s existence—for good reason: Although the U.S. Food and Drug Administration requires animal testing to determine the safety of most new drugs, the practice remains a hot-button topic, and the NIH facility doesn’t want its employees targeted by animal rights activists.

Yet “we think we have a really good story to tell,” Dr. Ruth Woodward says as a visitor gets a four-hour, behind-the-scenes tour. Woodward is the Shared Animal Facility’s veterinarian, and she notes: “Our mission is to put out research that can really help the country.”

The NIH purchased the Poolesville land in 1960 and built laboratories, animal pens and a power plant to guarantee electricity after the agency outgrew a facility near Gaithersburg. The center opened in 1965, and today serves as a holding area to ensure animals are free of disease before being used in research projects elsewhere. It’s also a research animal breeding center. But perhaps its most compelling function is as a base for behavioral and genetic research projects involving primates.

Nearly 100 people, including government employees, contractors, fellows and volunteers work at the center. Several live on-site to tend to the animals.

As of mid-August, there were about 1,400 monkeys, 100 mice, six pigs and five sheep living here. The NIH won’t detail all the research projects the animals are used for, but generally speaking, researchers use pigs for cardiovascular research; sheep and monkeys for immunity and social psychology study; and mice for assorted biomedical projects.

Dogs live at the facility on occasion (none on this particular day), but an NIH spokesperson emphasizes that they’re rarely used in research. Those that are used have been bred specifically for the purpose, with the goal of arriving at treatments for cancer and other ailments.

It’s mealtime at a 5-acre outdoor enclosure situated in a corner of the animal center. An employee wearing boots, blue protective clothing and a mask stands inside the electrified fence with a bucket of grapes and peanuts, which he begins throwing as dozens of rhesus monkeys surround him. They grab the treats and walk away, some with their tails in the air, showing their pink behinds to the visitors nearby.

He’s “wearing protective clothing and boots because monkeys do transmit disease, and we to them,” Woodward says of the worker.

The NIH built the enclosure nearly three decades ago for Dr. Stephen Suomi, the scientist who has been guiding and collaborating on research into social behavior among primates here. The research is funded by various organizations, including the Eunice Kennedy Shriver National Institute of Child Health & Human Development’s Division of Intramural Research, the National Cancer Institute, and the National Institute of Allergy and Infectious Diseases.

In 2011, Suomi received two grants from the Shriver institute: $1.25 million for research into how the environment impacts genes, and more than $800,000 to study how infant monkeys mimic their mothers.

A 1967 Stanford University graduate, Suomi was lured to NIH from the University of Wisconsin-Madison, where he had been researching the development of personality. Suomi’s graduate adviser and mentor was Harry Harlow, a University of Wisconsin psychology professor famous for demonstrating that contact and affection between mother monkeys and their infants were more important to social and cognitive development than food.

At NIH, Suomi studies rhesus monkeys because they share about 95 percent of human DNA. They also resemble humans in their ability to thrive in most climates, their tendency to live in social groups, and their mother-infant interactions.

Suomi has used the monkeys to study nature vs. nurture—particularly in regard to how environment impacts the development of personality. He also has studied how genetics influences the development of anxiety and depression, and how proper nurturing can alter those emotional states. As in humans, about 20 percent of rhesus monkeys are anxiety-prone, Suomi says.