Cooperation and individuality among man-eating lions

doi:10.1073/pnas.0905309106

Cooperation and individuality among man-eating lions

^aDepartment of Ecology and Evolutionary Biology, University of California, Santa Cruz, 1156 High Street, Santa Cruz, CA 95064;
^bDepartment of Zoology, Field Museum of Natural History, 1400 South Lake Shore Drive, Chicago, IL 60605;
^cDepartment of Geology, University of Puget Sound, 1500 North Warner Street, CMB 1048, Tacoma, WA 98416-1048;
^dLeverhulme Centre for Human Evolutionary Studies, University of Cambridge, Fitzwilliam Street, Cambridge CB2 1QH, United Kingdom;
^eDepartment of Geology and Geophysics, University of Utah, 135 South 1460 E, Salt Lake City, UT 84112;
^fDepartment of Ecology and Evolutionary Biology, University of California, Santa Cruz, 100 Shaffer Road, Santa Cruz, CA 95060; and
Departments of ^gEarth and Planetary Sciences and
^hAnthropology, University of California, Santa Cruz, 1156 High Street, Santa Cruz, CA 95064

Edited by Kristen Hawkes, University of Utah, Salt Lake City, UT, and approved September 25, 2009 (received for review May 13, 2009)

Abstract

Cooperation is the cornerstone of lion social behavior. In a notorious case, a coalition of two adult male lions from Tsavo, southern Kenya, cooperatively killed dozens of railway workers in 1898. The “man-eaters of Tsavo” have since become the subject of numerous popular accounts, including three Hollywood films. Yet the full extent of the lions' man-eating behavior is unknown; estimates range widely from 28 to 135 victims. Here we use stable isotope ratios to quantify increasing dietary specialization on novel prey during a time of food limitation. For one lion, the δ¹³C and δ¹⁵N values of bone collagen and hair keratin (which reflect dietary inputs over years and months, respectively) reveal isotopic changes that are consistent with a progressive dietary specialization on humans. These findings not only support the hypothesis that prey scarcity drives individual dietary specialization, but also demonstrate that sustained dietary individuality can exist within a cooperative framework. The intensity of human predation (up to 30% reliance during the final months of 1898) is also associated with severe craniodental infirmities, which may have further promoted the inclusion of unconventional prey under perturbed environmental conditions.

Footnotes

¹To whom correspondence may be addressed. E-mail: jyeakel{at}pmc.ucsc.edu or njdominy{at}ucsc.edu
Author contributions: J.D.Y., B.D.P., P.L.K., and N.J.D. designed research; J.D.Y., B.D.P., and N.J.D. performed research; K.F.-D., M.M.O., and T.E.C. contributed new reagents/analytic tools; J.D.Y., B.D.P., K.F.-D., J.W.M., P.L.K., and N.J.D. analyzed data; and J.D.Y., B.D.P., P.L.K., and N.J.D. wrote the paper.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission.
This article contains supporting information online at www.pnas.org/cgi/content/full/0905309106/DCSupplemental.