Philadelphia's senior simian is captured in bronze by local sculptor Eric Berg

The occasion was observed with appropriate fanfare—singing telegrams, a T-shirt from Clint Eastwood and his orangutan sidekick, Clyde, plus a three-tiered cake. It was the 50th birthday for Massa, the world's oldest captive gorilla, and the Philadelphia Zoo wasn't monkeying around: Artist Eric Berg was commissioned to sculpt Massa in bronze.

For the gorilla, who now moves slowly and seldom, the secret of longevity (by human standards, he's around 85) has been a steady diet of oranges, carrots, kale, "zoo cake" (a mixture of minerals, grains and meat) and an occasional goodie. "He's got a real sweet tooth," reports Massa's keeper of 22 years, Ralph McCarthy, who occasionally slips him the de rigueur delicacy these days, jelly beans.

Of course, Massa didn't always have it so good. Born in West Africa, he was orphaned as a suckling when his mother was killed while raiding a garden. Massa was breast-fed by a native—or so the story goes—and then shipped to America. For four years he lived in Brooklyn with an animal lover named Gertrude Lintz, who nursed him through pneumonia and taught him household chores. One day, however, she made the mistake of sneaking up on Massa while he was scrubbing the floor. She got 70 stitches, and he got a one-way ticket to the zoo.

Massa was welcomed by the zoo as a companion for its resident male gorilla, Bamboo. But after an explosive five days together, it was decided Massa should live alone. He has led a monastic existence ever since.

In fashioning his image, sculptor Berg hoped to capture the gorilla's "physical presence as well as the nobility, wisdom and tranquillity he has come to project in his old age." The statue, which took nine months to complete, was installed outside the Ape and Monkey House in December. It weighs 450 pounds; Massa himself is a relatively lean 300.

During sittings, Berg (who sketched from behind a glass wall) developed a certain rapport with his subject. "I respect Massa," he says. "He's a real dignified character, a Zen master of sorts. We just don't know what his great truths are." Berg speculates that the aging anthropoid is on the side "perhaps a veteran Wall Street financier. We know," winks Eric, "that he has accounts in several Swiss banks."

As a young artist, Berg, 35, has no pretensions to wealth. Raised in suburban Pottstown, Pa., he studied economics at the University of Pennsylvania. But he became interested in sculpting when he started whittling pipes at 21. He then earned an M.F.A. from Penn and scraped by teaching in a Quaker school. "If you're not willing to work for peanuts for a while," Berg reasons, "you won't find out what kind of artist you are."

Berg's interest in Massa dates to 1972, when he made a stone carving of the gorilla that sold for $350. He has also done a life-size Galapagos tortoise and a warthog but doesn't limit himself to animal sculpture. His abstracts adorn many public places around Philadelphia and include the $31,000 Figuresphere at Pennsylvania Hospital. "At a certain point," says Berg, "you realize you're no longer in the bargain business." The artist, who lives in a run-down house on the Penn campus, is divorced and shares custody of his 11-year-old son, Jesse, with his ex-wife, who resides on Society Hill.

Between commissions, Berg often drops in on the popular primate. "He is such a big draw," figures Berg, "that they ought to issue a credit card with his likeness." What would it be called? Massa Charge, of course.