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Craniofacial evolution in hominids and apes

Dr. Gary D. Richards

Investigation of the evolutionary history of our species allows for a much broader understanding of human craniofacial anatomy. On the one hand, research involving our most distant ancestors, Ardipithecus, Australopithecus, etc., provides an understanding of features of the human skull that are driven by changes in locomotion. These locomotor changes result in a significant restructuring of the skull, particularly in the nasal capsule, nasopharynx, and spinal cord regions. These modifications result in anatomical compromises that are the basis for numerous clinically relevant conditions in humans. On the other hand, focusing on only our own species, and closely related subspecies, provides us the ability to directly observe the primitive craniofacial form and how it has changed in the last ~300,000 years. We know that there has been positive selection on genes that both increase brain size and support its functions, but how these changes relate to other significant changes in craniofacial form (reduction of the face and dentition, significant changes in shape, etc.) are not known.

As a member of the Middle Awash Research Project, I have access to fossil remains of the earliest modern humans recovered recently at Herto, Ethiopia (160-180,000 years old). Because such old human remains were previously unknown, these new fossils mean that we are now in a position to delimit changes that resulted in the appearance of a modern human cranial shape. Also, we now have the basis for all subsequent geographic variations that derive from that original form. This means that we are very close to unlocking what our original ancestors looked like and what changes occurred in the evolution of all the modern variants.

My colleagues and I are employing a range of computed tomography facilities to generate images of varying resolutions (hospital CT, microCT, and synchrotron microCT) for our work on describing and interpreting fossil evidence from Herto, Ethiopia. Additionally, we are in the process of describing Neanderthal remains from Moula-Guercy, France. Although these remains are highly fragmented, we are employing 3D technologies to virtually reconstruct the crania.

Current projects and publications:

My work on the earliest modern human crania from Herto, Ethiopia will appear as a co-edited book with Dr. Berhane Asfaw, National Museum of Ethiopia, in a volume to be published by the University of California Press.

My colleagues and I are also currently preparing a series of publications that will serve as a descriptive catalogue for the Neanderthal remains from Moula-Guercy, France.

Contact:

Dr. Gary D. Richards, grichard@pacific.edu, 415.929.6573