http://www.washingtonpost.com/wp-dyn/content/article/2006/05/17/AR2006051702158.html#
And even later than you might imagine....
When the ancestors of human beings and the ancestors of chimpanzees parted ways 6.3 million years ago, it was probably a very long goodbye. Some of their descendants may even have gone back for a final tryst.
And even later than you might imagine....