Morphological evolution through integration: A quantitative study of cranial integration in Homo, Pan, Gorilla and Pongo

• Published in: Journal of human evolution Vol. 62; no. 1; pp. 155 - 164
• Main Authors: Singh, Nandini, Harvati, Katerina, Hublin, Jean-Jacques, Klingenberg, Christian P.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 2012; Elsevier
• Subjects: Animals; Biological and medical sciences; Biological Evolution; Chimpanzees; Craniometry; Evolution; Evolvability; Face; Fundamental and applied biological sciences. Psychology; Genetics of eukaryotes. Biological and molecular evolution; Geometric morphometrics; Gorillas; Hominidae - anatomy & histology; Hominids; Hominoids; Humans; Morphological integration; Morphology; Partial least square; Quantitative analysis; Skull - anatomy & histology; Taxonomy; Geometric morphometrics; Morphological integration; Hominoids; Evolvability; Partial least square; Interspecific comparison; Biological evolution; Pan troglodytes; Cranial suture; Vertebrata; Mammalia; Morphology; Primates; Simioidea; Skull; Morphometry
• ISSN: 0047-2484; 1095-8606; 1095-8606
• DOI: 10.1016/j.jhevol.2011.11.006

Morphological integration refers to coordinated variation among traits that are closely related in development and/or function. Patterns of integration can offer important insight into the structural relationship between phenotypic units, providing a framework to address questions about phenotypic evolvability and constraints. Integrative features of the primate cranium have recently become a popular subject of study. However, an important question that still remains under-investigated is: what is the pattern of cranial shape integration among closely related hominoids? To address this question, we conducted a Procrustes-based geometric morphometrics study to quantify and analyze shape covariation patterns between different cranial regions in Homo, Pan, Gorilla and Pongo. A total of fifty-six 3D landmarks were collected on 407 adult individuals. We then sub-divided the landmarks corresponding to cranial units as outlined in the ‘functional matrix hypothesis.’ Sub-dividing the cranium in this manner allowed us to explore patterns of covariation between the face, basicranium and cranial vault, using the two-block partial least squares approach. Our results suggest that integrated shape changes in the hominoid cranium are complex, but that the overall pattern of integration is similar among human and non-human apes. Thus, despite having very distinct morphologies the way in which the face, basicranium and cranial vault covary is shared among these taxa. These results imply that the pattern of cranial integration among hominoids is conserved.