The serious expressions in these faces tell me there is something more going on with these primates from the zoo. I often wonder, if they could talk, what would they have to say? I like the contrast in their fur when changing these to monochrome; it really brings out some nice details and works well with the lack of light that their enclosures have. Their haunting facial expressions stick with me that much more when I see them this way.
From @mmckinneyphoto13