The Bonobo (Pan paniscus), until recently usually called the Pygmy Chimpanzee and less often the Dwarf or Gracile Chimpanzee, is one of the two species comprising the chimpanzee genus, Pan. The other species in genus Pan is Pan troglodytes, or the Common Chimpanzee. Both species are chimpanzees, though that term is now frequently used to refer only to the larger of the two species, Pan troglodytes. Bonobos are capable of passing the mirror-recognition test for self-awareness. They communicate through primarily vocal means, although the meanings of their vocalizations are not currently known; however, humans do understand their facial expressions and some of their natural hand gestures, such as their invitation to play.