A researcher at the Krasnow Institute for Advanced Study, a biologist at the National Zoo, and a Ph.D. student in George Mason's Environmental Science and Public Policy program, Shumaker was one of the primary designers of the O-Line. Having the opportunity to provide the apes with "something so basic and important to them, allowing them to move in the way they've evolved to move," has been one of the great highlights of his career, says Shumaker.

But happy moments come with regularity for Shumaker. He is conducting the Orangutan Language Project with two orangutans at the National Zoo, a 22-year-old male named Azy and Azy's 19-year-old sister, Indah. The research began in March 1995, but Shumaker has known the apes much longer, having served as their caretaker since 1984. He says words can't describe the satisfaction he derives from his work with these primates.

This is the only cognition research project in the world in which the public may observe it as it is conducted, he says. Every weekday, he gives Azy and Indah one 45-minute lesson each, which visitors may sit and watch. "In the summertime, we average maybe 100 to 150 people watching each demonstration," says Shumaker.

Before each lesson, he explains the research to the crowd; afterward, he answers questions.

Like other researchers working at the zoo's Think Tank exhibit, Shumaker is interested in how other species think. He believes that cognitive research with humanity's close biological relatives can help scientists discover the boundaries of humanity--which skills and characteristics are uniquely human and which are not.

"It's clear that we have far more in common than we ever believed," he says. "For years, scientists believed that only humans have the capacity for making and using tools, but they soon discovered that, in fact, many animals make and use tools."

Currently, Shumaker is teaching Azy and Indah to recognize the numbers 1 through 3. So far, both Azy and Indah are identifying the correct number at a 70 to 80 percent accuracy rate.

Shumaker is, of course, not the first researcher to conduct language studies with great apes, but the number of studies conducted and the number of individual apes involved have been quite small, he says. Some studies involve teaching apes to use sign language, while other studies involve teaching written symbols. Shumaker is the first to conduct a study using written symbols with orangutans.

Shumaker is careful to point out that the animals participate voluntarily. There is no coercion. They receive the same amount of food each day and have the same amount of play time despite whether they do or do not participate. Sometimes, he says, the orangutans even refuse the treats. He recalls one exercise when Indah refused every treat he handed her. Finally, midway through the exercise, she reached out and took the bowl, threw the treats on the floor, and continued with the exercise--a-not-so-subtle hint that she wasn't in it just for the goodies.

With the data Shumaker collects during these demonstrations, he hopes to learn more about the general language abilities of orangutans, but he also wants to use the knowledge he gains about their language abilities as a platform to learn more about their general mental abilities. "I'd like to be able to explore broader concepts about how well they understand and perceive the world," he says.

But the excitement of learning about cognition in another species is the source of only part of the satisfaction the young researcher derives from his work. More satisfying still is the rapport he has developed with Azy and Indah. Says Shumaker: "When I go to work every day, it's like being around my best friends all day long."