It has been recently learned by researchers at the Max Planck Institute for Evolutionary Anthropology that the sexual status of a male bonobo is directly related their mother's social status. That piece of information does nothing for me. What is interesting is the image that accompanies the Science Daily story. Three things in the image, which captures a male bonobo chilling/thinking/daydreaming in a tree, catch the human eye: the ugliness of its feet, the humanness of its neck, and the enormous size of its balls.

His feet are ugly simply because they are more like hands (human hands) than feet (human hands). The length and slimness of its neck is, to use the words of the queen of the 19th century, Victoria, "frightful and painfully and disagreeably human." Finally its balls. Are they not as big as its brain? Indeed, how much tree-thinking (or tree-daydreaming) is possible when a considerable part of the ape's body is dedicated to its balls? It's biologically costly to have balls that are that big.