Understanding the forces that shaped the appearance and development of modern humans has been a leading goal of biological anthropology for decades. As technology has improved, our capability to investigate key questions about the factors affecting the shape of our anatomy have advanced significantly. Here, an interdisciplinary team of anthropologists and engineers will use engineering and experimental methods to examine how the shape of the skull has evolved in order to adapt to the forces associated with feeding on different types of food items. Specifically, the researchers will take a highly interdisciplinary approach to examining whether the skulls of these early humans were well designed to crack open and chew such hard, brittle objects. Dietary adaptations are thought to have been critical factors influencing the course of early human evolution, so this research project will provide valuable insights into the functional anatomy, diet, ecology and behavior of the earliest human ancestors.
With respect to intellectual merit, this project will: (a) examine the functional and evolutionary relationships between diet and skull form, (b) test a leading hypothesis explaining the evolution of the earliest humans, (c) collect and integrate multiple types of raw data critical to an understanding of feeding biomechanics, (d) develop methods for the rapid construction of engineering models that can be applied to research questions in a wide range of disciplines, (e) integrate ecological, comparative, experimental, and engineering techniques for the investigation of evolutionary questions, and (f) rapidly disseminate data, models and findings to the scientific community.
With respect to broader impacts, this study will: (a) promote interdisciplinarity, diversity and internationalism in science, (b) collect data about skull biomechanics that are relevant to dentistry and craniofacial medicine, (c) support the research of three junior investigators each in the first year of their academic appointments, (d) support female graduate students at several universities, (e) provide support to undergraduates at a university whose student body has a high proportion of minorities, (f) provide training for international students in developing nations (Brazil, Suriname), which will ultimately support the development of scientific infrastructure and institutions in those countries, (g) provide content to an exhibit focusing on human biology and evolution at the Georgia Children?s Museum, (h) using engineering models, limit the need for, or at least increase the analytical power of, future experimental studies requiring the use of live animals, (i) generate data relevant to conservation efforts by documenting the relationship between ecology and adaptation in certain primates, (j) strengthen collaborations between anthropologists and engineers in ten universities and two countries, (k) heighten awareness in the engineering community about how their methods are applicable to evolutionary questions.
This project used and improved finite element (FE) analysis, an engineering approach, to examine biological systems, especially how forces are transmitted through the head while biting and chewing. These methods allow scientists to model the biomechanics of human and other animal skulls with much greater accuracy and, in some areas of research, to reduce levels of invasive research on lab animals by allowing scientists to model stresses in a living system. The project constructed over a dozen models of monkeys, apes, and fossil human relatives. To make biologically realistic models, our team collected data on skull shape, muscle anatomy and strength, muscle use during biting and chewing, and bone strength across the skull in monkeys and chimpanzees. Well-constructed models continue to be time-consuming to create, so we have made our models available online for use by others. The project made new discoveries about how different skull shapes influence the stresses in the skull during biting and chewing on different teeth. It demonstrated the differences that can be found between individuals within a species (such as chimpanzees) compared with those between species (chimpanzees, macaques, capuchins). The research also improved our understanding of what wears down teeth over one's lifetime, and how tooth shape influences biting efficiency. Our team produced the first complete biomechanical models of the skulls of our ancient ancestors and relatives. These models demonstrated that the origin of human skull shape had profound affects on the pattern of stresses during chewing. The results reinforce ideas that changes in diet and how our ancestors ate accompanied the changes in skull shape observed in the human fossil record. This grant also provided support and training for six graduate students and two postdoctoral scientists, many who are now independent US scientists and teaching anatomy to medical and other health professions, or anthropology or biology to college students. This project strengthened collaborations between anthropologists, anatomists, and engineers at ten universities across the US in eight states and the Distric of Columbia, including universities that traditionally have not received NSF support. These include the University of Albany (New York), Arizona State University, The George Washington University (Washington, DC), University of Chicago (Illinois), Texas A&M University's Baylor College of Dentistry, University of Massachusetts at Amherst , Mercer University (Georgia), Florida State University, and Kansas City University of Medicine and Biosciences. The project also strengthened relationships and collaborations between scientists in Europe and these US scientists.
