Bamboo and Herman behaved like the best of friends since they were introduced five years ago, laughing and tickling each other as they played in their Lowry Park Zoo exhibit.'Everybody considered them buddies," David Murphy, the zoo's veterinarian, said of the elderly chimpanzees. 'They were like two old grandpas rolling around on the ground together.'On Friday, staff members were still puzzling over what prompted Bamboo to viciously attack his old friend. They were also grieving the loss of Herman, one of the zoo's oldest and most colorful characters, who blew kisses at women and was once known for smoking lighted cigarettes thrown at him by visitors. Murphy, who has worked at the zoo since 1986, said the cause of Herman's death was still unknown. He planned to perform a necropsy Friday afternoon.Murphy received a radio call about 12:30 p.m. Thursday alerting him to the fight. He rushed to the habitat, where zoo employees had already sprayed the chimps with water and ushered the females into the night house.'That usually quells any kind of disturbance,' Murphy said. 'That didn't happen this time. The males continued to fight.'It took another ten minutes to separate the aggressive males, he said. Herman was slumped over with his head bowed.The 42-year-old chimp's external injuries weren't extensive, Murphy said. Herman had puncture wounds on his lip and a torn fingertip and toe. He died shortly after 7 p.m. after hours of surgery. The fight appeared to be a struggle for dominance, common in the socially complex chimp world. They have a strict hierarchal order. Females ally with males, who fight to establish their rank within the group.Herman and Bamboo, who is 44, are the only adult male chimps at Lowry Park Zoo. There is an adolescent male, Alex, 8, who was 'totally confused' by the fight, Murphy said.There are also three females, Jamie, Rukiya and Twiggy, although Twiggy was in the night house when the fight erupted, Murphy said.Rukiya, 26, intervened in the fight and was injured, requiring stitches. She is expected to fully recover.Herman, who was born in Africa and lived at the zoo since 1965, was the dominant or alpha male.Zoo officials plan to introduce another chimp to the exhibit, 6-month-old Sasha.