<?xml version="1.0" encoding="UTF-8"?><xml><records><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Torres-Tamayo, Nicole</style></author><author><style face="normal" font="default" size="100%">Schlager, Stefan</style></author><author><style face="normal" font="default" size="100%">Hirasaki, Eishi</style></author><author><style face="normal" font="default" size="100%">Smith, Tim D.</style></author><author><style face="normal" font="default" size="100%">Rae, Todd C.</style></author><author><style face="normal" font="default" size="100%">Betti, Lia</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Comparative primate analysis shows that humans are not unique in having a tight cephalopelvic fit at birth</style></title><secondary-title><style face="normal" font="default" size="100%">Nature Ecology &amp;amp; Evolution</style></secondary-title></titles><dates><year><style  face="normal" font="default" size="100%">2026</style></year><pub-dates><date><style  face="normal" font="default" size="100%">2026/06/29</style></date></pub-dates></dates><urls><web-urls><url><style face="normal" font="default" size="100%">https://www.nature.com/articles/s41559-026-03102-5</style></url></web-urls></urls><isbn><style face="normal" font="default" size="100%">2397-334X</style></isbn><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">&lt;p&gt;Human childbirth is regarded as uniquely difficult among primates, due to a tight cephalopelvic fit thought to result from an evolutionary trade-off between adaptations to bipedal locomotion and increasing brain size. This impression, however, may be an artefact of past adoption of anthropocentric measurements that underestimate birth challenges in non-human primates. Here we re-evaluate cephalopelvic proportions using species-specific three-dimensional data of the pelvic inlet along with neonatal cranial dimensions from a broad sample of extant primates. Results reveal that maternal body size is a key factor to consider. A tight cephalopelvic fit occurs in species with proportionately larger neonates, smaller pelves or a combination of both. The latter is the case in humans, producing the tightest fit among extant apes, but a similar combination of factors explains much more extreme cephalopelvic proportions in other species. Our findings reveal a diversity of obstetrical dilemmas across primates.&lt;/p&gt;
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