TY - JOUR
T1 - Social bonds predict dominance trajectories in adult male chimpanzees
AU - Bray, Joel
AU - Feldblum, Joseph T.
AU - Gilby, Ian C.
N1 - Funding Information:
We thank the Tanzanian Wildlife Research Institute, Tanzania National Parks and the Tanzania Commission for Science and Technology for research permissions. We thank Jane Goodall and the Gombe Stream Research Center staff for their efforts over six decades to collect these data. We thank Anne Pusey for initiating digitization of the data and construction of the database. We thank the many research assistants at Duke University and the University of Minnesota for data entry. We thank Joan Silk, Kevin Langergraber, Veronika Stäedele, Anne Pusey and three anonymous referees for comments on previous drafts of the manuscript. Fieldwork was funded primarily by the Jane Goodall Institute. Additional support came from the U.S. National Science Foundation ( DBS-9021946 , SBR-9319909 , BCS-0452315 , IOS-LTREB-1052693 , IIS-0431141 ), the U.S. National Institutes of Health ( R01-AI058715 , R00-HD057992 , P30-AI27767 ), Harris Steel Group , the McKnight Foundation , the Windibrow Foundation , the Leakey Foundation , the Carnegie Corporation , the University of Minnesota , and Duke University . J.B. was supported by the National Science Foundation Graduate Research Fellowship under grant no. 026257-001 .
Funding Information:
We thank the Tanzanian Wildlife Research Institute, Tanzania National Parks and the Tanzania Commission for Science and Technology for research permissions. We thank Jane Goodall and the Gombe Stream Research Center staff for their efforts over six decades to collect these data. We thank Anne Pusey for initiating digitization of the data and construction of the database. We thank the many research assistants at Duke University and the University of Minnesota for data entry. We thank Joan Silk, Kevin Langergraber, Veronika St?edele, Anne Pusey and three anonymous referees for comments on previous drafts of the manuscript. Fieldwork was funded primarily by the Jane Goodall Institute. Additional support came from the U.S. National Science Foundation (DBS-9021946, SBR-9319909, BCS-0452315, IOS-LTREB-1052693, IIS-0431141), the U.S. National Institutes of Health (R01-AI058715, R00-HD057992, P30-AI27767), Harris Steel Group, the McKnight Foundation, the Windibrow Foundation, the Leakey Foundation, the Carnegie Corporation, the University of Minnesota, and Duke University. J.B. was supported by the National Science Foundation Graduate Research Fellowship under grant no. 026257-001.
Publisher Copyright:
© 2021 The Association for the Study of Animal Behaviour
PY - 2021/9
Y1 - 2021/9
N2 - In some species, individuals form well-differentiated and affiliative social relationships that facilitate cooperation and confer adaptive benefits, but few studies of males have addressed the benefits of same-sex social bonds. Among mammals, adult male chimpanzees, Pan troglodytes, form some of the strongest and most stable social bonds, and several studies have found that higher-ranking males attain short- and long-term benefits. No study in chimpanzees, however, has demonstrated a link between social bonds and dominance trajectories. To fill this gap, we used 37 years of data from Gombe National Park, Tanzania, to test the hypothesis that social bonds in adult male chimpanzees predict changes in dominance strength, which were measured by annual changes in mean Elo scores. Across 24 adult males, we found that social bonds, which were identified using both association in small groups and grooming activity, showed positive relationships with changes in dominance strength. From previous studies, the most likely mechanism for the observed relationship between adult male bond strength and dominance trajectories is the formation of cooperative coalitions, by which males with stronger bonds leverage established relationships to maintain or increase their position in the dominance hierarchy. Given the fission–fusion social structure of chimpanzees, both party-level associations and grooming relationships are essential components of male social bonding, and these results, in combination with prior studies, suggest that having strong social bonds is a valuable strategy for achieving higher rank.
AB - In some species, individuals form well-differentiated and affiliative social relationships that facilitate cooperation and confer adaptive benefits, but few studies of males have addressed the benefits of same-sex social bonds. Among mammals, adult male chimpanzees, Pan troglodytes, form some of the strongest and most stable social bonds, and several studies have found that higher-ranking males attain short- and long-term benefits. No study in chimpanzees, however, has demonstrated a link between social bonds and dominance trajectories. To fill this gap, we used 37 years of data from Gombe National Park, Tanzania, to test the hypothesis that social bonds in adult male chimpanzees predict changes in dominance strength, which were measured by annual changes in mean Elo scores. Across 24 adult males, we found that social bonds, which were identified using both association in small groups and grooming activity, showed positive relationships with changes in dominance strength. From previous studies, the most likely mechanism for the observed relationship between adult male bond strength and dominance trajectories is the formation of cooperative coalitions, by which males with stronger bonds leverage established relationships to maintain or increase their position in the dominance hierarchy. Given the fission–fusion social structure of chimpanzees, both party-level associations and grooming relationships are essential components of male social bonding, and these results, in combination with prior studies, suggest that having strong social bonds is a valuable strategy for achieving higher rank.
KW - Elo score
KW - Pan troglodytes schweinfurthii
KW - cooperation
KW - dominance strength
KW - social relationship
KW - sociality
UR - http://www.scopus.com/inward/record.url?scp=85111761226&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85111761226&partnerID=8YFLogxK
U2 - 10.1016/j.anbehav.2021.06.031
DO - 10.1016/j.anbehav.2021.06.031
M3 - Article
AN - SCOPUS:85111761226
SN - 0003-3472
VL - 179
SP - 339
EP - 354
JO - Animal Behaviour
JF - Animal Behaviour
ER -