Two abstracts are presented in order of completion. The first abstract was prepared for the 16th Biennial Conference on the Biology of Marine Mammals in San Diego, California. The second abstract was prepared for the International Polar Year in 2007-2008 and for the International Arctic Social Sciences Association and The VI International Congress of Arctic Social Sciences at Ilisimatusarfik, the University of Greenland, Nuuk, Greenland.
Hydrodynamic Sensor Capabilities and Structural Resilience of the Male Narwhal Tusk.
Nweeia, Martin T.1,2; Eidelman, Naomi3; Eichmiller, Frederick C.3; Giuseppetti, Anthony A.3; Jung, Yeon-Gil4; Zhang, Yu5
(1) Harvard University, School of Dental Medicine, 188 Longwood Avenue, Boston, MA 02115, USA
(2) Smithsonian Institution, Marine Mammal Program, Department of Zoology, 100 Constitution Avenue, Washington, D.C. 20056, USA
(3) ADAF Paffenbarger Research Center, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD 20899-8546, USA
(4) Changwon National University, School of Nano & Advanced Materials Engineering, 9 Sarim-dong, Changwon, Kyungnam, 641-773, Korea
(5) New York University, College of Dentistry, 345 East 24th Street, New York, NY 10010, USA
The unique configuration of dentinal tubules and hard tissue architecture within the narwhal tusk supports a new hypothesis for function. Two freshly harvested male tusks, examined under scanning electron microscopy, reveal dentinal tubules that are open and extend continuously from the pulp to the external environment. Approximately 1 tubule opening every 200 µm2, ranging from 0.1-4 µm are visible on the pulpal wall. Analogous surface lumena are visible within a 10-20 µm layer of diatoms and algae that cover the cementum surface. Brannstrom’s hydrodynamic theory identifies pain sensitivity in mammals that have tubule communication of pathologic origin from the tooth or root surface to the pulp. With over 106 tubules in an eight-foot tusk, potential exists for the tusk to be used as a hydrodynamic sensor to detect fluid flow responsive to gradients of salinity, temperature and pressure. Chemical and mechanical properties of the tusk also indicate unusual functional adaptation. Cross-sections of one tusk near the tip (#1), Ľ length from the tip (#2), and near the base (#3), were dry polished and mapped by Fourier-transform infrared reflectance microspectroscopy (FTIR-RM) at 100x100 µm to 200x200 µm spatial resolution and by nanoindentation at 200x100 µm spatial resolution. FTIR-RM analysis showed higher mineral to collagen ratios (MCR) near the dentin-pulp interface and decreasing toward the cementum interface in #1 and #2, with non significant difference in #3. Mechanical indices of hardness and Young’s Modulus were highest at the dentin-pulp interface and decreasing outward toward the cementum in all sections. All three properties declined from tip to base, with modulus demonstrating dramatic decline moving from pulp to the outer surface. The outer layers being less mineralized and more flexible than the inner layers in sections closer to the tip indicate unusual resilience and flexibility of the tusk and suggest important evolutionary functional adaptation.
Martin Nweeia, DMD Harvard University, School of Dental Medicine and Smithsonian Institution, Marine Mammal Program: Inuit and Western Descriptions of the Narwhal, Connecting Parallel Perceptions: Studies of the Narwhal Tooth Expeditions and Research Investigation.
Abstract: Scientists with myriad backgrounds and Inuit elders with traditional knowledge will combine results and insights to discover the purpose and function of the erupted tusk of the narwhal. This extraordinary tooth defies most of the principles and properties of teeth and remains a scientific enigma. Findings about its form and function will add to the evolutionary knowledge for this odd adaptation and will, because of unique findings of anatomy and histology recently discovered by this team, further define sensory capabilities of mammalian teeth. Scientific results have already begun to direct interest in future models of dental material design as the hard tissue of the narwhal tusk possesses a combination of unusual flexibility and strength characteristics that is highly desirable in restorative materials. These same tusk traits were observed by the Inuit before the laboratory testing was completed, and the results were reported. Likewise, traditional knowledge elucidates many aspects of narwhal anatomy, function, and behavior.
Description: Both the knowledge of Inuit elders and the findings of scientists are needed for a more complete understanding of the narwhal, Qilalugaq qumertaq. Often these worlds run parallel to each other. Scientists collect and analyze data without consulting Inuit elders. Similarly, elders do not choose among scientific results when deciding which information will be preserved within their oral traditions. Field work will continue in the recording of Inuit traditional knowledge about the narwhal, and is important for two reasons. First, some Inuit are astute observers of nature and their environment. Elders have the added advantage of observing the narwhal in various situations and conditions over a broader span of time. Second, they are able to comment on and help clarify scientific findings that are conflicting and mired in confusion. At the onset of the study, it became apparent that another value of these recordings was to preserve this knowledge. As younger Inuit become displaced from their hunting traditions and lifestyle, they are showing less interest in learning about them. The communities of Pond Inlet, Arctic Bay, Clyde River and Broughton Island have been identified as locations within Nunavut, Canada having strong associations with narwhal. Those in Greenland have also been identified as Qaanaaq, Disco Bay, Hunde Ejland, and Uummannaaq. A questionnaire of approximately 60 questions has been compiled and translated into one Inuktitut dialect and used for 8 interviews of elders in Pond Inlet and Arctic Bay. Interviews have been and will continue to be conducted with interpreters present and recorded using a 3 CCD video and digital or tape audio format. We are still seeking translators and interpreters for the remaining communities and contacts to facilitate the collection of information.
Scientific studies in anatomy, histology and cellular biology are currently being conducted by the principle investigator and collaborators to elucidate tusk function. Anatomical variations of narwhal will be described from previous field and laboratory dissection, computerized scans (CT, MRI and micro CT), analysis of museum specimens, and interviews with Inuit elders. Though we have visited and begun photometric analysis of narwhal skeletal collections at the Museum of Nature in Canada, Zoological Museum, University of Copenhagen, the Smithsonian Institution and the American Museum of Natural History, we are still seeking others that may have additional collections, particularly those with rare specimens. Anatomic plates of narwhal anatomy will be completed based on these findings. Recent scientific results have directed attention to ice formation and salinity gradients in the Arctic so we are seeking collaborative efforts with investigators collecting and mapping this information in Arctic waters.
Joint presentations with the principle investigator and Inuit elders will be encouraged and planned to express the value of scientific collaboration with Inuit elders. Our main objective in this social science component study is to move these parallel perceptions of Western scientific thinking and Inuit Elder traditional knowledge into a single line of understanding and appreciation for the narwhal and potentially other Arctic species.
National Institute of Standards and Technology, Paffenbarger Research Center
Smithsonian Institution, Marine Mammal Program and the Arctic Studies Center
Hauschka Bone Laboratory, Children’s Hospital, Boston and Harvard School of Medicine
John Hopkins, School of Medicine, Imaging Department
Harvard School of Dental Medicine
Harvard Museum of Comparative Zoology
Fisheries and Oceans Canada, Arctic Research Division
Optimal CAE, Inc., Engineering Metrology Group
Polar Institute of Japan
University of Tokyo International Coastal Research Center, Ocean Research Institute
Arctic Studies Center, Nunavut
Nunavut Wildlife Management Board
Hunters and Trappers Organizations within Nunavut
Nunavut Research Institute
Neuroscience Laboratory, Olin Neuropsychiatry Research Center, Institute of Living, Hartford, CT
Webb Research Corporation