Hard Tissue Biology - Laboratory Research

Gorilla dentine

The microanatomical structure of hard tissues preserves a record of their growth history, and in the case of bone, the factors that influence its maintenance throughout life. As such, they represent a unique source of information about individual developmental history, which cannot be gleaned from macroscopic studies of the skeleton alone. Our current research projects seek to address several major questions:

  • How does hard tissue development and microanatomical structure vary within and among wild primate populations? How does this variation relate to observed differences in life history, behavior, ecology, and environment?
  • What can tooth and bone microanatomy tell us about stress in primate lives?
  • How can examinations of hard tissue microanatomy inform our understanding of the life history, developmental biology and health of modern populations, and offer insights into the evolution of human life history?

 

See below to learn about some of our projects. Please feel free to contact us for more information.


Hard tissue biology and life history of Virunga mountain gorillas from Rwanda

Our ability to accurately interpret variability in hard tissue microanatomy in unknown animals will ultimately depend on opportunities to investigate individuals for which life history, behavior and environment is known. As part of the Mountain Gorilla Skeletal Project, we have been engaged in an interdisciplinary and collaborative program of fieldwork and laboratory-based research that investigates relationships between hard tissue biology and life history in a well-documented population of Virunga mountain gorillas from Rwanda, many of whom were observed in life by Dian Fossey and other staff from the Karisoke Research Center. As mountain gorillas represent an ecological and life history extreme among apes, research on their bones and teeth can add significantly to our understanding of the comparative development and life history of great apes in the wild. Further, since detailed life records are available for many individuals in the collection, this represents an extraordinary opportunity to test relationships between variation in hard tissue development and structure and observed features of their life history, behavior and environment. Knowledge gleaned from these studies will complement information obtained from the ongoing monitoring of mountain gorillas in life, and provide unique insights into their conservation and evolutionary biology. (Funding: National Geographic Society’s Committee for Exploration and Research, Leakey Foundation, and National Science Foundation).

 

Photograph and xray image of an erupting first permanent molar in the lower jaw of a mountain gorilla.

 

 

 


Significance of primary bone microstructure for life history 

While hard tissue research on primate life history has tended to focus on dental development, among investigators of other vertebrate groups there is a long tradition of examining the microanatomy of bone for the information it can provide about growth rates and maturational timing.

Our work has demonstrated that features of primary bone tissues, understood to record variability in bone depositional rates during growth, exhibit significant ontogenetic and taxonomic variation among Old World monkeys and apes. While lamellar bone tissues are prevalent among adults of all species, there is considerable variability among species in the succession of faster-forming tissue types deposited during ontogeny. This variability reflects important differences in postnatal growth patterns, and demonstrates the potential of bone microstructure as an independent source of information about developmental aspects of primate life history. (Funding: The Leakey Foundation, National Science Foundation).

Color-coded tissue type map, midshaft femur, juvenile chimpanzee. Scale = 1.0mm.

 


Comparative primate bone microstructure 

The microscopic structure of bone represents an important source of information about phylogenetic, ontogenetic, environmental, and local/functional factors that influence its formation and subsequent remodeling throughout life. Bone microstructural analyses therefore have the potential to complement studies of whole bone morphology, and provide unique insight into behavior. Secondary remodeling is a process of bone turnover, which exhibits significant variability among species, within single skeletons, and among individuals of different ages. Though attention has focused on the biomechanical significance of secondary remodeling, factors accounting for variability in its distribution within and among skeletons remain poorly understood. By examining its regional patterning within skeletal sites throughout ontogeny, we have sought to understand the manner in which developmental and mechanical factors may interact to produce the taxonomic and intraskeletal patterning of secondary bone remodeling in primates. (Funding: The Leakey Foundation, NSF).

Secondary bone remodeling at the midshaft femur of a chimpanzee, imaged in circularly polarized light. Field width = 1.5mm.