L’accouchement de nos ancêtres était-il dystocique ?

摘要

The aim of this study was to assess the risk of foetal-pelvic disproportion in extinct hominins through a comparison of current obstetrical data with fossil data. For the modern sample, we collected pelvic diameters, foetal cranial diameters and delivery outcomes from 92 obstetrical cases (spontaneous vaginal, N = 43; c-section for foetal-pelvic disproportion, N = 34; operative vaginal, N = 15). For the fossil sample, the diameters of 12 pelvises and 6 juvenile skulls were gathered from the literature. Our estimations of neonatal skull sizes were based on (1) juvenile skull measurements and cranial growth curves and (2) the neonatal brain size estimations of DeSilva and Lesnik (2008). A linear discriminant analysis (LDA) was performed on the obstetrical cases. Despite a 35% misclassification error, the results showed a vaginal delivery range, an obstructed delivery range and an intermediate range where delivery outcomes were unpredictable. The multiple combinations between pelvic reconstructions and neonatal cranial estimations were projected onto the LDA and were mostly within the range of normal labour, with probabilities being within the range of normal labour (eutocia) at 0.99 ± 0.01 for Australopithecines; 0.76 ± 0.15 for Homo erectus s.l.; and 0.86 ± 0.08 for Neandertals.