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Dimorphism in the Size and Shape of the Birth Canal Across Anthropoid Primates
Author(s) -
Moffett Elizabeth A.
Publication year - 2017
Publication title -
the anatomical record
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.678
H-Index - 62
eISSN - 1932-8494
pISSN - 1932-8486
DOI - 10.1002/ar.23572
Subject(s) - sexual dimorphism , birth canal , biology , cephalopelvic disproportion , zoology , pregnancy , genetics , caesarean section
It has long been noted that the human female birth canal is well adapted to giving birth to large‐brained neonates. However, several species of nonhuman primates give birth to large‐headed neonates compared to the maternal birth canal. The presence of such large cephalopelvic proportions in nonhuman primates presents the question of whether dimorphism in the birth canals of these other species is related to obstetric demand, as such dimorphism is presumed to be in humans. In this study, the hypothesis that either the presence or magnitude of dimorphism in the birth canal is related to large cephalopelvic proportions among anthropoid primates is directly tested. This study shows that birth canal dimorphism is common among anthropoids regardless of cephalopelvic proportions, but taxa with large cephalopelvic proportions have a higher magnitude of dimorphism than those that give birth to relatively small‐headed neonates. Furthermore, humans have exceptionally high levels of dimorphism that cannot be explained based on our large cephalopelvic proportions alone. Anat Rec, 300:870–889, 2017. © 2017 Wiley Periodicals, Inc.