Cultural transmission of tool use in bottlenose dolphins
- *School of Biological, Earth, and Environmental Sciences, University of New South Wales, Sydney NSW 2052, Australia; ‡Departments of Biology and Psychology, Georgetown University, Washington, DC 20057; §Department of Biological Sciences, Marine Biology Program, Florida International University, North Miami, FL 33181; ¶Department of Biology, University of Massachusetts, North Dartmouth, MA 02748; and ∥Department of Biology, Dalhousie University, Halifax, NS, Canada B3H 4J1
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Edited by Peter Marler, University of California, Davis, CA, and approved April 29, 2005 (received for review January 12, 2005)

Abstract
In Shark Bay, wild bottlenose dolphins (Tursiops sp.) apparently use marine sponges as foraging tools. We demonstrate that genetic and ecological explanations for this behavior are inadequate; thus, “sponging” classifies as the first case of an existing material culture in a marine mammal species. Using mitochondrial DNA analyses, we show that sponging shows an almost exclusive vertical social transmission within a single matriline from mother to female offspring. Moreover, significant genetic relatedness among all adult spongers at the nuclear level indicates very recent coancestry, suggesting that all spongers are descendents of one recent “Sponging Eve.” Unlike in apes, tool use in this population is almost exclusively limited to a single matriline that is part of a large albeit open social network of frequently interacting individuals, adding a new dimension to charting cultural phenomena among animals.
Footnotes
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↵ † To whom correspondence should be sent at the present address: Anthropological Institute and Museum, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland. E-mail: michael.kruetzen{at}aim.unizh.ch.
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Author contributions: M.K. designed research; M.K., M.R.H., R.C.C., L.B., and W.B.S. performed research; M.K. contributed new reagents/analytic tools; M.K., J.M., and R.C.C. analyzed data; and M.K. and W.B.S. wrote the paper.
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This paper was submitted directly (Track II) to the PNAS office.
- Copyright © 2005, The National Academy of Sciences