title: Basis for cumulative cultural evolution in chimpanzees: social learning of a more efficient tool-use technique.
abstract: BACKGROUND
  The evidence for culture in non-human animals has been growing incrementally over the past two decades. However, the ability for cumulative cultural evolution, with successive generations building on earlier achievements, in non-human animals remains debated. Faithful social learning of incremental improvements in technique is considered to be a defining feature of human culture, differentiating human from non-human cultures. This study presents the first experimental evidence for chimpanzees' social transmission of a more efficient tool-use technique invented by a conspecific group member.
  
  
  RESULTS
  The chimpanzees were provided with a straw-tube, and spontaneously demonstrated two different techniques in obtaining juice through a small hole: "dipping" and "straw-sucking". Both the "dipping" and "straw-sucking" techniques depended on the use of the same tool (straw-tube) for the same target (juice) accessible from exactly the same location (small hole 1 cm in diameter). Therefore the difference between "dipping" and "straw-sucking" was only in "technique". Although the two techniques differed significantly in their efficiency, their cognitive and perceptuo-motor complexity were comparable. All five chimpanzees who initially performed the "dipping" technique switched to using the more efficient "straw-sucking" technique upon observing a conspecific or human demonstrate the more proficient alternate "straw-sucking" technique.
  
  
  CONCLUSIONS
  The social learning mechanism involved here was clearly not local or stimulus enhancement, but imitation or emulation of a tool-use technique. When there is no biologically relevant difference in cognitive or perceptuo-motor complexity between two techniques, and when chimpanzees are dissatisfied with their own technique, chimpanzees may socially learn an improved technique upon close observation of a proficient demonstrator. This study provides important insights into the cognitive basis for cumulative culture in chimpanzees, and also suggests possible conditions in which cumulative cultural evolution could arise even in non-human animals.
authors: Primate Research Institute, Kyoto University, Inuyama, Aichi, Japan. shinyayamamoto1981@gmail.com
authors: Shinya
authors: S
authors: Yamamoto
authors: Tatyana
authors: T
authors: Humle
authors: Masayuki
authors: M
authors: Tanaka
mesh_terms: D000818:Animals; D001522:Behavior, Animal; D003468:Cultural Evolution; D005260:Female; D007858:Learning; D008297:Male; D002679:Pan troglodytes / Q000523:psychology*; D053001:Tool Use Behavior
references: Am J Primatol. 2010 Jan;72(1):17-24
references: 19731231
references: Anim Cogn. 2003 Dec;6(4):213-23
references: 12898285
references: Am J Primatol. 2008 Jul;70(7):699-702
references: 18459112
references: Science. 2003 Jan 3;299(5603):102-5
references: 12511649
references: J Comp Psychol. 1996 Mar;110(1):3-14
references: 8851548
references: PLoS One. 2010 May 19;5(5):e10625
references: 20502702
references: Am J Primatol. 2002 Nov;58(3):133-48
references: 12454957
references: J Hum Evol. 2008 Jul;55(1):48-59
references: 18275983
references: Anim Cogn. 2009 Mar;12(2):209-16
references: 18766391
references: J Comp Psychol. 2000 Sep;114(3):291-6
references: 10994845
references: J Hum Evol. 1999 Jun;36(6):719-41
references: 10330335
references: Proc Natl Acad Sci U S A. 2006 Sep 12;103(37):13878-83
references: 16938863
references: Nature. 2005 Sep 29;437(7059):737-40
references: 16113685
references: Primates. 2004 Jan;45(1):25-32
references: 14566573
references: Folia Primatol (Basel). 1990;54(1-2):86-99
references: 2157651
references: Psychol Sci. 2009 Dec;20(12):1478-83
references: 19891752
references: Anim Cogn. 2005 Jul;8(3):164-81
references: 15549502
references: Philos Trans R Soc Lond B Biol Sci. 2009 Aug 27;364(1528):2405-15
references: 19620111
references: Proc Natl Acad Sci U S A. 2007 Feb 27;104(9):3043-8
references: 17360606
references: Anim Cogn. 2003 Dec;6(4):235-44
references: 13680401
references: Behav Brain Sci. 2006 Aug;29(4):329-47; discussion 347-83
references: 17094820
references: Learn Behav. 2004 Feb;32(1):4-14
references: 15161136
references: Anim Cogn. 2008 Jul;11(3):449-56
references: 18204869
references: Nature. 1999 Jun 17;399(6737):682-5
references: 10385119