Map of the Neolithic necropolis of Gurgy (Yonne, France).

<p>Map of the Neolithic necropolis of Gurgy (Yonne, France).</p

Result of PCA on the EDJ shape coordinates on form space, according to occupation phases.

<p>Result of PCA on the EDJ shape coordinates on form space, according to occupation phases.</p

Dendrogram from cluster analysis based on 3D tissue proportions.

<p>Bootstrap values are indicated on nodes.</p

Measured 2D variables of crown tissue proportions for each individual.

<p>Measured 2D variables of crown tissue proportions for each individual.</p

Topographic variation of standardized enamel thickness measured on the lingual (continuous lines) and buccal (dotted lines) aspects according to burial structures.

<p>Topographic variation of standardized enamel thickness measured on the lingual (continuous lines) and buccal (dotted lines) aspects according to burial structures.</p

The 20 Neolithic individuals sampled in the necropolis of Gurgy.

<p>Details of biological (age and sex, maturational and wear stages, mtDNA haplogroups) and chronocultural parameters (radiocarbon age, phase, burial structure, orientation and location in the necropolis).</p

Internal Tooth Structure and Burial Practices: Insights into the Neolithic Necropolis of Gurgy (France, 5100-4000 cal. BC) - Fig 3

<p>Plot of Evol against DPvol (top) and plot of DPvol against AET3D (graphic representation of RET3D, bottom) according to burial (left) and phase (right).</p

Result of PCA on the EDJ shape coordinates on form space, according to burial structures.

<p>Result of PCA on the EDJ shape coordinates on form space, according to burial structures.</p

Descriptive statistics of measured 3D variables for all individuals, female and male individuals, separately.

<p>Descriptive statistics of measured 3D variables for all individuals, female and male individuals, separately.</p

Short Faces, Big Tongues: Developmental Origin of the Human Chin

<div><p>During the course of human evolution, the retraction of the face underneath the braincase, and closer to the cervical column, has reduced the horizontal dimension of the vocal tract. By contrast, the relative size of the tongue has not been reduced, implying a rearrangement of the space at the back of the vocal tract to allow breathing and swallowing. This may have left a morphological signature such as a chin (mental prominence) that can potentially be interpreted in <i>Homo</i>. Long considered an autopomorphic trait of <i>Homo sapiens</i>, various extinct hominins show different forms of mental prominence. These features may be the evolutionary by-product of equivalent developmental constraints correlated with an enlarged tongue. In order to investigate developmental mechanisms related to this hypothesis, we compare modern 34 human infants against 8 chimpanzee fetuses, whom development of the mandibular symphysis passes through similar stages. The study sets out to test that the shared ontogenetic shape changes of the symphysis observed in both species are driven by the same factor – the space restriction at the back of the vocal tract and the associated arrangement of the tongue and hyoid bone. We apply geometric morphometric methods to extensive three-dimensional anatomical landmarks and semilandmarks configuration, capturing the geometry of the cervico-craniofacial complex including the hyoid bone, tongue muscle and the mandible. We demonstrate that in both species, the forward displacement of the mental region derives from the arrangement of the tongue and hyoid bone, in order to cope with the relative horizontal narrowing of the oral cavity. Because humans and chimpanzees share this pattern of developmental integration, the different forms of mental prominence seen in some extinct hominids likely originate from equivalent ontogenetic constraints. Variations in this process could account for similar morphologies.</p> </div