Evolutionary and Comparative Anatomy

STS 5, Australopithecus africanus Sterkfontein, South Africa STS 5, Australopithecus africanus Sterkfontein, South Africa

My initial interest in craniofacial biology began with an interest in human evolution.  The striking range of craniofacial morphologies in the hominin lineage, from the ape-like Australopithecus afarensis to the extreme adaptations in Australopithecus boisei, has inspired many researchers to seek answers to the endless array of questions regarding the myriad influences acting on the different components.  Much of my early work investigating evolutionary changes in craniofacial form focused on a component of the cranial base, the temporal bone.  The temporal bone could easily be considered the most complex bone in the skull as it has a unique ontogenetic history with at least five developmental units readily defined: squamous, tympanic, petromastoid, styloid and the bony labyrinth.  It contains two major functional complexes, the masticatory and auditory apparatus, as well as relationships with the brain and local musculature.  This complexity has made the temporal bone a useful tool in phylogenetic assessment of fossil hominins.

Part of my interest in the temporal bone arose from my association with the Baringo Paleontological Research Project (BPRP) directed by Andrew Hill of Yale University.  This project began investigating the Tugen Hills succession in the Lake Baringo area of Kenya in 1981 and my first trip to Baringo was in 1988.  This region contains sedimentary units ranging from 200,000  to 16 million years old.  Included in the fossil finds from this area is a partial temporal bone (known as the Chemeron Temporal) dated to 2.4 million years old.  Part of my dissertation research was to conduct comparative anatomical studies of the temporal bone of hominins and apes and to consider the taxonomic placement of the Chemeron Temporal.  I agreed with earlier assessments (by Steve Ward and Andrew Hill) that the evidence supports placement of this specimen into the genus Homo making this specimen the earliest fossil evidence for the genus that includes humans.  Other interesting fossils from this area inlcude the partial upper limb skeleton of Equatorius africanus, a ~15.5 million year old ape.

KNM-WT 17000, Australopithecus aethiopicus Lomekwi, Kenya KNM-WT 17000, Australopithecus aethiopicus Lomekwi, Kenya

After working in the Baringo Basin for several years I initiated an ill-fated fieldwork project of my own.  The area of interest was the Lake Rukwa Basin of Southeastern Tanzania.  This region has produced tantalizing evidence of hominid occupation in the form of stone tools and a number of interesting fossils have been found in Malawi adjacent to the Tanzanian border.  My colleague, John Kingston, and I were successful in obtaining funding for the project form the National Science Foundation and the National Geographic Society and traveled to the region in 2001.  Despite being armed with state-of-the-art satellite imagery, and numerous geologic reports of plio-pleistocene aged sediments, we found only one area with fossiliferous deposits (most likely mesozoic in age). Such luck is not unusual and demonstrates that, even with proper preparation, there is always an element of luck when searching for fossils.  While this trip did not produce the fossils we had hoped for, we enjoyed our time in Tanzania, a spectacularly beautiful country.

In 2002, I became interested in exploring the genetic underpinnings of  cranial variation.  While this work has a strong biomedical component, it also has strong relevance to questions regarding the evolution of the primate skull and I continue to present and publish in this discipline.

Funding

References

Bellisari A, Duren DL, and Sherwood RJ. 2004. Infant gorilla growth and development. Presented at the 3rd Annual Great Lakes Regional Gorilla Workshop Columbus Zoo and Aquarium, Columbus, OH November 3-4, 2004).

Bellisari A, Duren DL, and Sherwood RJ. 2005. Sex difference in emergence of deciduous dentition in captive lowland gorillas (Gorilla gorilla gorilla). Am J Phys Anthropol Suppl. 40:75.

Bellisari A, Duren DL, Sherwood RJ, and Barrie M. 2004. A captive infant female gorilla with vitamin D and calcium deficiency: preliminary description. Am J Phys Anthropol Suppl. 38:61.

Duren DL, Sherwood RJ, Lee M, Siervogel RM, and Towne B. 2009. Human bipedality and the genetic architecture of a locomotor system. Am J Phys Anthropol 138(Suppl. 48):180-181.

May RL, and Sherwood RJ. 1999. Shape measurements of the early hominid cranial base. J Hum Evol 36:A11.

McNulty KP, Duren DL, Blangero J, Dyer T, Cole SA, Lee M, Siervogel RM, Towne B, and Sherwood RJ. 2009. The geometry and architecture of craniofacial inheritance. Am J Phys Anthropol 138(Suppl.48):289.

Nicolay CW, and Sherwood RJ. 2000. Eigenshape and biomechanical analysis of the phyllostomid mandibular symphysis. American Zoologist 40:1148.

Pangas SA, Lovejoy CO, Sherwood RJ, Adams KC, Adams CS, Meindl RS, and Hudson JAK. 1992. The last common human mitochondrial DNA ancestor may be early Pleistocene in age. Presented at the International Conference on Molecular Evolution.  June 11-14, 1992.

Rowley RB, and Sherwood RJ. 2002. Ontogeny and allometry of mandibular fossa placement in African apes. Am J Phys Anthropol Suppl. 34:134.

Sherwood RJ. 1986. Dietary Adaptations of the Plio-Pleistocene Hominidae. Masters Thesis. Kent State University.

Sherwood RJ. 1994. Radiographic anatomy of the temporal bone of fossil hominids. Am J Phys Anthropol Suppl. 18:180.

Sherwood RJ. 1995. The Hominid Temporal Bone: Ontogeny and Phylogenetic Implications. Dissertation. Kent State University.

Sherwood RJ. 1997. Ontogeny of temporal bone pneumatization in the hominoidea. J Morphol 232:322.

Sherwood RJ. 1998. Review of "Children of the Ice Age: How a global catastrophe allowed humans to evolve" by Steven Stanley. Rep Nat C Sci Edu 18:22-23.

Sherwood RJ. 1999. Pneumatic processes in the temporal bone of chimpanzee (Pan troglodytes) and gorilla (Gorilla gorilla). J Morphol 241:127-137. 

Sherwood RJ. 2004. Review of "Human Paleobiology" by Robert Eckhardt. Rep Nat C Sci Edu 24:36-37.

Sherwood RJ. 2005. The Ape in the Tree: An Intellectual & Natural History of Proconsul (review). Am J Hum Biol 17:826-827.

Sherwood RJ, and Duren DL. 2009. The genetics of morphology. Am.J.Phys.Anthropol. 138(/Suppl. 48):369.

Sherwood RJ, Duren DL, Blangero J, Czerwinski SA, and Towne B. 2004. Genetic architecture of the human craniofacial complex with paleontological implications. J Morphol 260:328.

Sherwood RJ, Duren DL, Blangero J, Dyer T, Cole SA, Siervogel RM, and Towne B. 2005. The Search for the Real Missing Link: Finding the Genes that Influence Craniofacial Morphology. Paleoanthropol PAS 2005 Abstracts:A40.

Sherwood RJ, Duren DL, Blangero J, Mahaney MC, and Towne B. 2006. Face value: Comparative quantitative genetics of the human (Homo sapiens) and baboon (Papio hamadryas) craniofacial complex. Paleoanthropol PAS 2006 Abstracts:A01.

Sherwood RJ, Duren DL, Blangero J, and Towne B. 2005. Phyletic valence of craniofacial traits: clues from quantitative genetics. Am J Phys Anthropol Suppl. 40:194.

Sherwood RJ, Duren DL, Mahaney MC, Havill LM, and Towne B. 2006. Integration and modularity in the baboon craniofacial complex. Available from www.craniofacialgenetics.org

Sherwood RJ, Emch VC, Hlusko LJ, and Walker A. 1997. The mandibular symphysis of Australopithecus. J Hum Evol 32:A19-A20.

Sherwood RJ, Hlusko LJ, Duren DL, Emch VC, and Walker A. 2005. Mandibular symphysis of large-bodied hominoids. Hum Biol 77:735-759. 

Sherwood RJ, and Kingston JD. 2002. Paleoanthropological survey of the Lake Rukwa Basin, Tanzania. Am J Phys Anthropol Suppl. 34:141.

Sherwood RJ, Mahaney MC, Duren DL, Havill LM, Cox LA, Rogers J, and Towne B. 2008. Variation, genetics, and evolution of the primate craniofacial complex. Am J Phys Anthropol Suppl. 43:192.

Sherwood RJ, and May RL. 2000. The status of early Homo. Am J Phys Anthropol Suppl. 30:280.

Sherwood, RJ, McNulty, KP, Duren, DL, Mahaney, MC, Williams-Blangero, S, Siervogel, RM, Towne, B. Dissecting the genetic architecture of craniofacial shape. (Invited paper: Presented at the First International Conference on Biological Shape Analysis. June 3-6, 2009, Tsukuba, Japan).

Sherwood RJ, Rowley RB, and Ward SC. 2001. Relative placement of the mandibular fossa. Am J Phys Anthropol Suppl. 32:136-137.

Sherwood RJ, Rowley RB, and Ward SC. 2002. Relative placement of the mandibular fossa in great apes and humans. J Hum Evol 43:57-66. 

Sherwood RJ, Ward S, Hill A, Duren DL, Brown B, and Downs W. 2002. Preliminary description of the Equatorius africanus partial skeleton (KNM-TH 28860) from Kipsaramon, Tugen Hills, Baringo District, Kenya. J Hum Evol 42:63-73. 

Sherwood RJ, and Ward SC. 1989. Development of temporal bone pneumatization in the African great apes. Am J Phys Anthropol 78:301.

Sherwood RJ, Ward SC, and Hill A. 1996. Mandibular fossa anatomy of the Chemeron temporal bone (KNM-BC 1). Am J Phys Anthropol 22 (Supplement):214-215.

Sherwood RJ, Ward SC, and Hill A. 2002. The taxonomic status of the Chemeron temporal (KNM-BC 1). J Hum Evol 42:153-184.