at Mt. Okorobiko of Rio Muni, Equatorial Guinea. Research done by C. Jones and J. Sabater Pi from 19 to 19 8. old age See senescence. open eyes Plooij Eyes open. See video. open mouth See play face and yawn. Some individuals open mouth when showing relaxed face. open mouth kiss See kiss with open mouth. open thighs Goodall Male invite: male sits with thighs splayed and penile erection, looking toward a female in estrus. Sometimes his hair is erect 128 orphan 129 Male courtship display. Similar pattern in bonobos. See video. orphan Dependent offspring who has survived mothers death. Usually accompanies adult males, particular adult female, or sibling. See adopt. ostracize Most members of unit group punish or expel individual from group by repeated, concerted attack. Reported