of mutual grooming at Mahale, Kibale, Lop, Budongo, Ta and Semliki, but not at Gombe or Bossou. In captivity, done by chimpanzees at Yerkes Primate Research Center. Seen in bonobos of Wamba, Lomako and Lui Kotale. 5. See video. See also video groom-hand-clasp unilaterally. groom-hand-clasp unilaterally One grooming partner assumes typical hand clasp posture, but does not groom companion; instead rests or grooms ground, although being groomed. 9. See video. groom leaf Goodall Leaf-grooming: A leaf may be suddenly picked, seemingly at random. Holding the leaves in one hand, the chimp makes grooming movements with both thumbs, often pushing his lower lip to the leaf surface as in social grooming. Other chimps often crowd around to look. After a few minutes the leaves are discarded. It seems to