spatial proximity to one another, this pant-hooting is reduced, as opposed to situations in which members are temporarily spatially separated and constantly travelling. In travelling situations, pant-hoots are used to assist in the maintenance of the group's connection, and awareness of the whereabouts of each of their affiliative partners. In addition, when individuals are in complete absence and isolation of their social partners, pant-hoot production is significantly reduced, and upon reuniting within certain spatial boundaries, pant-hooting and communication between the partners resume. Spatial contact between members of a chimpanzee party may be maintained to uphold the fitness benefits brought upon by the social affiliation with other chimpanzees. Social bonds can be identified by the reciprocal grooming and support during intraspecific conflicts, and these affiliative behaviours can be announced in the face of third-party males by the production of pant-hoot choruses which demonstrate their dominance and strength as a group. Dominance rank among male chimpanzees is tied hand-in-hand with mating and reproductive success, therefore, the maintenance of the social group and the affiliation with other individuals brings an adaptive benefit in the establishment of higher dominance rankings, therefore increasing their reproductive success, and essentially overall fitness. This in turn illustrates the adaptive benefit of spatial communication and contact with allies that sustain the highest potential for contributing fitness benefits to the overall group. Variation/modification The modifications and variability observed within the chimpanzee pant-hoots can be attributed to differences in the structure and the production of these vocalizations. Structural differences in the pant hoot have been observed with respect to behavioural context, such as in the production of chorusing, habitat composition and genetic differentiation with respect to geographic separation and differences based upon experience and vocal learning. Additionally, the overall production and level of pant-hoot expression vary based on the dominance rank of individuals and the risks imposed by location and human interactions. Structure The general structure of chimpanzee pant-hoots (introduction, build-up, climax and let-down) can be variable between populations, including instances of additions/removals of certain phrases, changes in the duration of each phrase and the rearrangement of the general sequential pattern of phrases, with these modifications being easily identified by researchers, experts and other human listeners. These structural differences may be attributed to behavioural contexts, genetic differences between members of different populations due to geographic separation, and consequently, varying habitat conditions and learning based upon experience (vocal learning). Chimpanzees have been