Photographer Captures Hilarious Close Up Portraits of Some of the World's Most Unusual Primates

For over two decades, photographer Mogens Trolle has captured stunning wildlife photos on all seven continents. Trained as a zoologist and wildlife biologist, he specializes in mammals and uses his knowledge of them—as well his keen eye—to capture each creature’s unique personality.

Mandrill in the mood: "Several times during the almost half an hour he sat in front of me he would make this curious facial expression, a crooked smile and twisting the tongue. Normally you would think of showing teeth as a threat, but a mandrill researcher has told me that this particular display is meant to show friendly intentions. He definitely did appear friendly. From the wild in Gabon."