Evidence of Lévy walk foraging patterns in human hunter–gatherers

Edited by Simon A. Levin, Princeton University, Princeton, NJ, and approved November 22, 2013 (received for review October 2, 2013)
December 23, 2013
111 (2) 728-733

Significance

Lévy walks are a random walk search strategy used by a wide variety of organisms when searching for heterogeneously distributed food. This type of search involves mostly short move steps (defined as the distance traveled before pausing or changing direction) combined with rarer longer move steps. Here, we show that the Hadza, hunter–gatherers from northern Tanzania, perform Lévy walks when foraging for a wide variety of food items, suggesting that Lévy walks are an important movement pattern for the most cognitively complex foragers on Earth. Our results suggest that scale-invariant, superdiffusive movement profiles are a fundamental feature of human landscape use, regardless of the physical or cultural environment, and may have played an important role in the evolution of human mobility.

Abstract

When searching for food, many organisms adopt a superdiffusive, scale-free movement pattern called a Lévy walk, which is considered optimal when foraging for heterogeneously located resources with little prior knowledge of distribution patterns [Viswanathan GM, da Luz MGE, Raposo EP, Stanley HE (2011) The Physics of Foraging: An Introduction to Random Searches and Biological Encounters]. Although memory of food locations and higher cognition may limit the benefits of random walk strategies, no studies to date have fully explored search patterns in human foraging. Here, we show that human hunter–gatherers, the Hadza of northern Tanzania, perform Lévy walks in nearly one-half of all foraging bouts. Lévy walks occur when searching for a wide variety of foods from animal prey to underground tubers, suggesting that, even in the most cognitively complex forager on Earth, such patterns are essential to understanding elementary foraging mechanisms. This movement pattern may be fundamental to how humans experience and interact with the world across a wide range of ecological contexts, and it may be adaptive to food distribution patterns on the landscape, which previous studies suggested for organisms with more limited cognition. Additionally, Lévy walks may have become common early in our genus when hunting and gathering arose as a major foraging strategy, playing an important role in the evolution of human mobility.

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Acknowledgments

We thank the Hadza for their participation, cooperation, and hospitality. Herieth Cleophas, Fides Kirei, Lieve Lynen, Nathaniel Makoni, Carla Mallol, Ruth Mathias, Elena Mauriki, Daudi Peterson, and Christopher and Nani Schmelling provided invaluable help in the field. We thank the Tanzanian National Institute for Medical Research and Tanzania Commission for Science and Technology for permission to conduct this study. Funding was provided by National Science Foundation Grant BCS-0850815, and A.D.G. was funded, in part, by a Wenner–Gren Foundation Hunt Postdoctoral Fellowship.

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Information & Authors

Information

Published in

Go to Proceedings of the National Academy of Sciences
Go to Proceedings of the National Academy of Sciences
Proceedings of the National Academy of Sciences
Vol. 111 | No. 2
January 14, 2014
PubMed: 24367098

Classifications

Submission history

Published online: December 23, 2013
Published in issue: January 14, 2014

Keywords

  1. Lévy flight
  2. Brownian motion
  3. superdiffusion
  4. scale invariance
  5. optimal foraging

Acknowledgments

We thank the Hadza for their participation, cooperation, and hospitality. Herieth Cleophas, Fides Kirei, Lieve Lynen, Nathaniel Makoni, Carla Mallol, Ruth Mathias, Elena Mauriki, Daudi Peterson, and Christopher and Nani Schmelling provided invaluable help in the field. We thank the Tanzanian National Institute for Medical Research and Tanzania Commission for Science and Technology for permission to conduct this study. Funding was provided by National Science Foundation Grant BCS-0850815, and A.D.G. was funded, in part, by a Wenner–Gren Foundation Hunt Postdoctoral Fellowship.

Notes

This article is a PNAS Direct Submission.

Authors

Affiliations

David A. Raichlen1 [email protected]
School of Anthropology, University of Arizona, Tucson, AZ 85721;
Brian M. Wood
Department of Anthropology, Yale University, New Haven, CT 06520;
Adam D. Gordon
Department of Anthropology, University at Albany, Albany, NY 12222;
Audax Z. P. Mabulla
Archaeology Unit, University of Dar es Salaam, Dar es Salaam, Tanzania;
Present address: National Museum of Tanzania, Dar es Salaam, Tanzania.
Frank W. Marlowe
Department of Anthropology, Cambridge University, Cambridge CB2 1QH, United Kingdom;
Herman Pontzer
Department of Anthropology, Hunter College, New York, NY 10065; and
New York Consortium for Evolutionary Primatology, NY

Notes

1
To whom correspondence should be addressed. E-mail: [email protected].
Author contributions: D.A.R., B.M.W., A.Z.P.M., F.W.M., and H.P. designed research; D.A.R., B.M.W., A.Z.P.M., F.W.M., and H.P. performed research; D.A.R., B.M.W., A.D.G., and H.P. analyzed data; and D.A.R., B.M.W., A.D.G., A.Z.P.M., F.W.M., and H.P. wrote the paper.

Competing Interests

The authors declare no conflict of interest.

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    Evidence of Lévy walk foraging patterns in human hunter–gatherers
    Proceedings of the National Academy of Sciences
    • Vol. 111
    • No. 2
    • pp. 565-876

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