The median life expectancy for a chimpanzee is 31 although some have been known to live until 50.
Zoo officials are not sure at this point exactly what killed the chimpanzee, but they are keeping a very close eye on the others.
"People are just devastated. It's like losing a member of your own personal family that people come in and work with this animal every day. So it's really hard for everybody," said Dr. Steve Thompson, Lincoln Park Zoo.
At nine years of age, Kipper was the youngest of seven chimpanzees at the Lincoln Park Zoo.
On Thursday afternoon, the others are nowhere to be found at their exhibit. Zookeepers have them quarantined, hoping to keep them from developing similar symptoms to kipper. They say they noticed last week some of the chimpanzees had something similar to the flu, coughing, congestion, reduced activity. By Monday, Kipper suffered from severe congestion and labored breathing. By Tuesday morning, they say he seemed to be more alert during a visit and they believed he was getting better.
"Everybody thought okay, we have turned the corner here. They went back to check him 20 minutes later and he stopped breathing," said Dr. Thompson.
Doctors have done a necropsy on Kipper's body. The results from that will not be back likely before about two weeks. In the meantime, zoo officials say that the other chimpanzees in quarantine. The other six include Kipper's mother, Cashew. So far they have not observed any visible reaction in Cashew to her son's death.