log blocks path, infant moves onto log, then resumes ride on her back after mother passes under log. 3. See video. avoid incest Does not mate with close relatives such as parent, sibling or offspring. Incest avoidance known from many mammals and birds. See incest. A B B baboon See respond to baboon. backstroke Solo locomotor play. Infant or young juvenile slides supine downwards, on slope covered with dry leaves, head first while kicking ground with feet, while keeping both arms ahead. Performed by juvenile male, Michio, and infant female, Athena. 9. See video. Bai Hokou Study area of Pan troglodytes troglodytes in Dzanga-Sangha region of Central African Republic. Research done by RW Carroll in 19881989. balance Nishida Aeroplane, Plooijs Balance: Mother or adult/ adolescent alloparent lying supine