A Bornean orangutan (Pongo pygmaeus), apparently deep in thought, sits in a clump of Pandanus palms by the riverside, Sekonyer River, Tanjung Puting National Park, Indonesia. (captioned after the famous Rodin bronze by the same name)
As soon as I saw this, before reading your title, I thought "The Thinker" - :-) Great minds, right. This is a wonderful capture, and so very interesting. You can see how huge their hands are here, which is a clue to the size of the whole body. This is great!