I found a news article about Chimpanzees mourning a dead friend. I personally think this behavior is what separates us primates from other animals. The only two animals that display this behavior is us and the chimpanzees. It shows an understanding of death and the emotional loss of a loved one. Most animals only care about themselves. Chimpanzees mostly only care about themselves, but they do mourn the dead as well as kiss and teach. This and other human like behaviors such as kissing, warfare, and murder displayed by chimpanzees is important, because it perhaps shows how we evolved the behaviors that make us human. At the very least it supports the common ancestor theory. Here is the link to the article.

Please Read my other post about chimpanzee behavior: It is scary how similar we are to Chimpanzees