Grieving Chimpanzees?

The recent spate of news accounts of Common chimpanzees 'grieving' over dead or dying members of their species (http://www.telegraph.co.uk/earth/wildlife/6444909/Chimpanzees-grief-caught-on-camera-in-Cameroon.html) is not exactly 'cut and dried'. It is by no means unusual for animals to show an interest in dead or dying conspecifics but this does not prove that the emotion felt is directly comparable to human grief. One has to be a bit wary about 'suggestive' photographs that appear a little 'staged'. Having said that they are our closest relatives.