Taronga Zoo keepers have been saddened to farewell one of their oldest chimpanzees, ‘Bessie’ today. Bessie had celebrated her 60th birthday last year, an impressive milestone which made her one of the oldest chimpanzees cared for by a zoo anywhere in the world. The grand old dame, who over the years had shown signs of dementia, had recently been experiencing some other age related complaints and over the last few days her condition had deteriorated rapidly.  It’s believed Bessie’s organs were shutting down, and the difficult decision was made to humanely end her life.Taronga Veterinarian, Frances Hulst said: “Although this was a very difficult decision, it was the right decision to make. We owed it to Bessie, one of our favourite chimpanzees, to alleviate her suffering and allow her to slip away peacefully.”Taronga Zoo’s Primate Manager, Louise Grossfeldt, who has worked closely with Bessie during her entire career, said: “Over the last few days our chimp group have taken their time to say goodbye. They knew the end was near for our old girl, and took the time they needed to farewell her.”Sharing 98 percent the same genetics as humans, the average life expectancy of a chimpanzee is about 40-45 years, although in zoos they can live far longer due to the expert veterinary and keeper care they receive.Bessie is succeeded by two other elderly chimpanzees, ‘Spitter’ and ‘Lulu’ who turned 58 late last year.