be a form of displacement or redirection. At Mahale, chimpanzee puts small louse in folded leaf and kills it. Louse egg is also crushed during leaf-grooming. Customary at Gombe, Mahale, Kibale and present at Budongo, but not seen at Ta and Bossou, nor in bonobos of Wamba. See also inspect leaf and squash leaf. 5. See video. groom mutually Goodall Mutual grooming. Two chimpanzees groom each other simultaneously. Common in chimpanzees, but occurs in Wamba bonobos only during role changes of social grooming. Also rare at Lomako. Humans may not groom mutually. 3. See video. groom object or substrate Groom soil, leaves on ground, tree trunk, or moss on rock, usually with one hand. Solitary or social grooming, even during grooming-hand-clasp. Seen G 88 grunt, aha in only