A troop of chimpanzees at Chicago's Lincoln Park Zoo celebrate the 50th birthday of Keo, a male chimpanzee in their troop, on June 26, 2008. Keo is one of the oldest chimps in any US zoo, so this marked a major milestone. Of the four chimps in their social group, Kibali (pictured), a 28-year-old female, seems to have enjoyed the special treats the most. The 600-pound fruit filled ice sculpture was created and donated by Nadeau's Ice Sculpture, Inc. AFP PHOTO / Lincoln Park Zoo / Greg NEISE == RESTRICTED TO EDITORIAL USE ONLY / NO SALES / GETTY OUT ==