Some excerpts:

On September 23, 2008, Dorothy, a female chimpanzee in her late 40s, died of congestive heart failure. A maternal and beloved figure, Dorothy had spent eight years at Cameroon’s Sanaga-Yong Chimpanzee Rescue Center, which houses and rehabilitates chimps victimized by habitat loss and the illegal African bushmeat trade....The management at Sanaga-Yong opted to let Dorothy's chimpanzee family witness her burial, so that perhaps they would understand, in their own capacity, that Dorothy would not return. Some chimps displayed aggression while others barked in frustration. But perhaps the most stunning reaction was a recurring, almost tangible silence. If one knows chimpanzees, then one knows that [they] are not [usually] silent creatures