mouth. Functions as reassurance and coalition formation, and sometimes during copulation. Rarely, juvenile male presses teeth against objects, such as mass of dry leaves. Absent in bonobos of Wamba. See video. probe Use vine, stem, bark, grass, twig, or stick to touch object. Goodalls Investigation probe. Infant chimpanzees appear innately inclined to push investigatory probe into tree hole, long before starting to fish for arboreal ants. Juvenile sometimes inserts probe inside of large fruit such as Voacanga to try to obtain juice. Customary at Gombe, Mahale, Bossou, and Ta. Present at Goualougo and Kibale. Probing for bees is customary at Ta and present at Mahale. Absent in bonobos of Wamba. See video. See also video probe with finger. probe nasal passage Adult male, Kalunde, inserted probe into nostril