Not much was known about the Allen's swamp monkey in the 1950s, so the Zoo was excited to receive a young pair in 1953, the first in a U.S. zoo. That excitement was doubled on June 10, 1959, when a baby was born, the first birth of the species in the U.S. Mammal curator George Pournelle noted that the baby grew quickly, and that by 10 weeks of age he was eating bits of his mother's food. The staff was also interested to see that reports of this species liking water and swimming were true—a large tub of water was eagerly used for splashing and dunking.