IADR Abstract Archives

Pathology of an archaic Homo mandible from Kanam, Kenya

Objectives: The Kanam mandible was discovered by Louis Leakey's paleontological team in Kanam, Kenya, 1932. Tooth and jaw size and morphology suggest assignment to archaic Homo of the African Middle or Late Pleistocene. The bone has an asymmetric swelling on the posterior symphysis, which Phillip Tobias (Witwatersrand University) originally suggested was the result of a pathological process such as osteosarcoma , bone keloid, Burkitt lymphoma, or osteomyelitis secondary to fracture. Fortunately, Leakey sectioned the mandible obliquely through this swelling, enabling a re-examination of its mineral composition and bone structure, in an attempt to understand the processes, both geological and pathological, that contributed to its unusual form.

Methods: A Hitachi 3500-N SEM, fitted with a Robinson detector and a PGT x-ray microanalysis (XRM) system, permitted backscattered electron (BSE) imaging and mineral composition analysis respectively. Elemental maps of elements Ca, P, S, and Si from sectioned sample surfaces were generated. These maps were used to determine where bone mineral (calcium phosphate) was located in relation to the sedimentary matrix surrounding the fossil (calcium carbonates, silicates, etc.).

Results: The Kanam mandible contains an abundance of cancellous bone of varying mineral density; there is no discrete circumferential bone cortex. The cancellous bone is composed of calcium phosphate while available space in the bone consists of a calcium carbonate and silicate matrix. The microstructure shows lamellar structure and osteocyte lacunae. Evident trabecular fragmentation appears to be a post-mortem development related to geologic processes (sediment expansion-contraction cycles). However, many areas of reparative bone remodeling with abundant osteocyte spaces and reversal lines were observed, indicating pathology.

Conclusion: The Kanam mandible, after tens of thousands of years in lime-rich sediments, retained its calcium phosphate bone composition. Furthermore, while geological processes have fractured the specimen, both its macro- and microanatomy are consistent with bone pathology secondary to fracture.


AADR/CADR Annual Meeting
2006 AADR/CADR Annual Meeting (Orlando, Florida)
Orlando, Florida
2006
1036
Mineralized Tissue
  • Weiner, Michael Joseph  ( New York University College of Dentistry, New York, NY, USA )
  • Ricci, John L.  ( New York University College of Dentistry, New York, NY, USA )
  • Phelan, Joan  ( New York University, New York, NY, USA )
  • Plummer, Thomas  ( Queens College, City University of New York, N/A, N/A, USA )
  • Gauld, S.  ( Santa Monica College, N/A, N/A, USA )
  • Potts, R.  ( Smithsonian Institution, N/A, N/A, USA )
  • Bromage, Timothy G.  ( New York University, New York, NY, USA )
    • Poster Session
    Osteogenesis/Pathology
    03/10/2006