title: The evolution of self-control.
abstract: Cognition presents evolutionary research with one of its greatest challenges. Cognitive evolution has been explained at the proximate level by shifts in absolute and relative brain volume and at the ultimate level by differences in social and dietary complexity. However, no study has integrated the experimental and phylogenetic approach at the scale required to rigorously test these explanations. Instead, previous research has largely relied on various measures of brain size as proxies for cognitive abilities. We experimentally evaluated these major evolutionary explanations by quantitatively comparing the cognitive performance of 567 individuals representing 36 species on two problem-solving tasks measuring self-control. Phylogenetic analysis revealed that absolute brain volume best predicted performance across species and accounted for considerably more variance than brain volume controlling for body mass. This result corroborates recent advances in evolutionary neurobiology and illustrates the cognitive consequences of cortical reorganization through increases in brain volume. Within primates, dietary breadth but not social group size was a strong predictor of species differences in self-control. Our results implicate robust evolutionary relationships between dietary breadth, absolute brain volume, and self-control. These findings provide a significant first step toward quantifying the primate cognitive phenome and explaining the process of cognitive evolution.
authors.affiliation: Departments of Evolutionary Anthropology, maclean@duke.edu.
authors.forename: Evan L
authors.initials: EL
authors.lastname: MacLean
authors.affiliation: Departments of Evolutionary Anthropology,Center for Cognitive Neuroscience.
authors.forename: Brian
authors.initials: B
authors.lastname: Hare
authors.affiliation: Departments of Evolutionary Anthropology.
authors.forename: Charles L
authors.initials: CL
authors.lastname: Nunn
authors.affiliation: Istituto di Scienze e Tecnologie della Cognizione Consiglio Nazionale delle Ricerche, 00197 Rome, Italy;
authors.forename: Elsa
authors.initials: E
authors.lastname: Addessi
authors.affiliation: Department of Developmental and Comparative Psychology, Max Planck Institute for Evolutionary Anthropology, D-04103 Leipzig, Germany;
authors.forename: Federica
authors.initials: F
authors.lastname: Amici
authors.affiliation: Department of Biology, Duke University, Durham, NC 27704;
authors.forename: Rindy C
authors.initials: RC
authors.lastname: Anderson
authors.affiliation: Instituto de Neuroetologia, Universidad Veracruzana, Xalapa, CP 91190, Mexico;Research Centre in Evolutionary Anthropology and Palaeoecology, Liverpool John Moores University, Liverpool L3 3AF, United Kingdom;
authors.forename: Filippo
authors.initials: F
authors.lastname: Aureli
authors.affiliation: Center for Interdisciplinary Brain Sciences Research andDepartment of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, CA 94305;
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Baker
authors.affiliation: Center for Animal Care Sciences, Smithsonian National Zoological Park, Washington, DC 20008;
authors.forename: Amanda E
authors.initials: AE
authors.lastname: Bania
authors.affiliation: Department of Brain and Cognitive Science and.
authors.forename: Allison M
authors.initials: AM
authors.lastname: Barnard
authors.affiliation: Department of Psychology and Neuroscience, University of St. Andrews, St. Andrews KY16 9JP, Scotland;
authors.forename: Neeltje J
authors.initials: NJ
authors.lastname: Boogert
authors.affiliation: Center for Cognitive Neuroscience,Psychology and Neuroscience, and.
authors.forename: Elizabeth M
authors.initials: EM
authors.lastname: Brannon
authors.affiliation: Department of Psychology, University of Pennsylvania, Philadelphia, PA 19104;
authors.forename: Emily E
authors.initials: EE
authors.lastname: Bray
authors.affiliation: Departments of Evolutionary Anthropology.
authors.forename: Joel
authors.initials: J
authors.lastname: Bray
authors.affiliation: Center for Cognitive Neuroscience,Duke Institute for Brain Sciences, Duke University, Durham, NC 27708;
authors.forename: Lauren J N
authors.initials: LJ
authors.lastname: Brent
authors.affiliation: Anthropological Institute and Museum, University of Zurich, 8057 Zurich, Switzerland;
authors.forename: Judith M
authors.initials: JM
authors.lastname: Burkart
authors.affiliation: Department of Developmental and Comparative Psychology, Max Planck Institute for Evolutionary Anthropology, D-04103 Leipzig, Germany;
authors.forename: Josep
authors.initials: J
authors.lastname: Call
authors.affiliation: Department of Brain and Cognitive Science and.
authors.forename: Jessica F
authors.initials: JF
authors.lastname: Cantlon
authors.affiliation: Department of Psychology, University of Cambridge, Cambridge CB2 3EB, United Kingdom;
authors.forename: Lucy G
authors.initials: LG
authors.lastname: Cheke
authors.affiliation: Department of Psychology, University of Cambridge, Cambridge CB2 3EB, United Kingdom;
authors.forename: Nicola S
authors.initials: NS
authors.lastname: Clayton
authors.affiliation: Department of Psychology and.
authors.forename: Mikel M
authors.initials: MM
authors.lastname: Delgado
authors.affiliation: Department of Comparative Medicine, Seneca Park Zoo, University of Rochester, Rochester, NY 14620;
authors.forename: Louis J
authors.initials: LJ
authors.lastname: DiVincenti
authors.affiliation: Graduate School of Letters, Kyoto University, Kyoto 606-8501, Japan;
authors.forename: Kazuo
authors.initials: K
authors.lastname: Fujita
authors.affiliation: Department of Developmental and Comparative Psychology, Max Planck Institute for Evolutionary Anthropology, D-04103 Leipzig, Germany;
authors.forename: Esther
authors.initials: E
authors.lastname: Herrmann
authors.affiliation: Graduate School of Letters, Kyoto University, Kyoto 606-8501, Japan;
authors.forename: Chihiro
authors.initials: C
authors.lastname: Hiramatsu
authors.affiliation: Department of Psychology andHelen Wills Neuroscience Institute, University of California, Berkeley, CA 94720;
authors.forename: Lucia F
authors.identifier: http://orcid.org/0000-0003-0330-9700
authors.initials: LF
authors.lastname: Jacobs
authors.affiliation: Departments of Psychology and.
authors.forename: Kerry E
authors.initials: KE
authors.lastname: Jordan
authors.affiliation: Department of Psychology, University of Kentucky, Lexington, KY 40506;
authors.forename: Jennifer R
authors.initials: JR
authors.lastname: Laude
authors.affiliation: Department of Psychology, Yale University, New Haven, CT 06520;
authors.forename: Kristin L
authors.initials: KL
authors.lastname: Leimgruber
authors.affiliation: Department of Psychology and Neuroscience, University of St. Andrews, St. Andrews KY16 9JP, Scotland;
authors.forename: Emily J E
authors.initials: EJ
authors.lastname: Messer
authors.affiliation: Departamento Engenharia e Meio Ambiente, Universidade Federal da Paraiba, 58059-900, João Pessoa, Brazil;
authors.forename: Antonio C de A
authors.initials: AC
authors.lastname: Moura
authors.affiliation: Department of Psychology, University of Cambridge, Cambridge CB2 3EB, United Kingdom;
authors.forename: Ljerka
authors.initials: L
authors.lastname: Ostojić
authors.affiliation: Department of Psychology, University of York, Heslington, York YO10 5DD, United Kingdom;
authors.forename: Alejandra
authors.initials: A
authors.lastname: Picard
authors.affiliation: Departments of Evolutionary Anthropology,Center for Cognitive Neuroscience,Duke Institute for Brain Sciences, Duke University, Durham, NC 27708;Neurobiology, and.
authors.forename: Michael L
authors.initials: ML
authors.lastname: Platt
authors.affiliation: Department of Psychology, University of Cambridge, Cambridge CB2 3EB, United Kingdom;Think Elephants International, Stone Ridge, NY 12484;
authors.forename: Joshua M
authors.initials: JM
authors.lastname: Plotnik
authors.affiliation: Messerli Research Institute, University of Veterinary Medicine Vienna, 1210 Vienna, Austria;Wolf Science Center, A-2115 Ernstbrunn, Austria;
authors.forename: Friederike
authors.initials: F
authors.lastname: Range
authors.affiliation: Department of Biology, McGill University, Montreal, QC, Canada H3A 1B1;
authors.forename: Simon M
authors.initials: SM
authors.lastname: Reader
authors.affiliation: Department of Anthropology, University of Michigan, Ann Arbor, MI 48109; and.
authors.forename: Rachna B
authors.initials: RB
authors.lastname: Reddy
authors.affiliation: Department of Anthropology, University of Michigan, Ann Arbor, MI 48109; and.
authors.forename: Aaron A
authors.initials: AA
authors.lastname: Sandel
authors.affiliation: Department of Psychology, Yale University, New Haven, CT 06520;
authors.forename: Laurie R
authors.initials: LR
authors.lastname: Santos
authors.affiliation: Department of Developmental and Comparative Psychology, Max Planck Institute for Evolutionary Anthropology, D-04103 Leipzig, Germany;
authors.forename: Katrin
authors.initials: K
authors.lastname: Schumann
authors.affiliation: Department of Psychology and Neuroscience, University of St. Andrews, St. Andrews KY16 9JP, Scotland;
authors.forename: Amanda M
authors.initials: AM
authors.lastname: Seed
authors.affiliation: Department of Biology, Duke University, Durham, NC 27704;
authors.forename: Kendra B
authors.initials: KB
authors.lastname: Sewall
authors.affiliation: Department of Psychology, University of Cambridge, Cambridge CB2 3EB, United Kingdom;
authors.forename: Rachael C
authors.initials: RC
authors.lastname: Shaw
authors.affiliation: Department of Psychology, University of York, Heslington, York YO10 5DD, United Kingdom;
authors.forename: Katie E
authors.initials: KE
authors.lastname: Slocombe
authors.affiliation: Department of Psychology, Peking University, Beijing 100871, China.
authors.forename: Yanjie
authors.initials: Y
authors.lastname: Su
authors.affiliation: Graduate School of Letters, Kyoto University, Kyoto 606-8501, Japan;
authors.forename: Ayaka
authors.initials: A
authors.lastname: Takimoto
authors.affiliation: Departments of Evolutionary Anthropology.
authors.forename: Jingzhi
authors.initials: J
authors.lastname: Tan
authors.affiliation: Department of Psychology and Neuroscience, University of St. Andrews, St. Andrews KY16 9JP, Scotland;
authors.forename: Ruoting
authors.initials: R
authors.lastname: Tao
authors.affiliation: Anthropological Institute and Museum, University of Zurich, 8057 Zurich, Switzerland;
authors.forename: Carel P
authors.initials: CP
authors.lastname: van Schaik
authors.affiliation: Messerli Research Institute, University of Veterinary Medicine Vienna, 1210 Vienna, Austria;
authors.forename: Zsófia
authors.initials: Z
authors.lastname: Virányi
authors.affiliation: Istituto di Scienze e Tecnologie della Cognizione Consiglio Nazionale delle Ricerche, 00197 Rome, Italy;
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Visalberghi
authors.affiliation: Department of Psychology, University of Kentucky, Lexington, KY 40506;
authors.forename: Jordan C
authors.initials: JC
authors.lastname: Wade
authors.affiliation: Department of Psychology, University of Cambridge, Cambridge CB2 3EB, United Kingdom;
authors.forename: Arii
authors.initials: A
authors.lastname: Watanabe
authors.affiliation: Department of Psychology, Yale University, New Haven, CT 06520;
authors.forename: Jane
authors.initials: J
authors.lastname: Widness
authors.affiliation: Wildland Resources, Utah State University, Logan, UT 84322;
authors.forename: Julie K
authors.initials: JK
authors.lastname: Young
authors.affiliation: Department of Psychology, University of Kentucky, Lexington, KY 40506;
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Zentall
authors.affiliation: Department of Psychology, Peking University, Beijing 100871, China.
authors.forename: Yini
authors.initials: Y
authors.lastname: Zhao
mesh_terms: D000818:Animals; D005075:Biological Evolution; D001921:Brain / Q000033:anatomy & histology / Q000502:physiology*; D003071:Cognition; D004032:Diet; D006801:Humans; D007858:Learning; D016013:Likelihood Functions; D015233:Models, Statistical; D009929:Organ Size; D010802:Phylogeny; D011323:Primates / Q000033:anatomy & histology / Q000502:physiology*; D011340:Problem Solving; D012641:Selection, Genetic; D012919:Social Behavior; D013045:Species Specificity
keywords: behavior; comparative methods; executive function; inhibitory control; psychology
references.citation: Proc Natl Acad Sci U S A. 2013 Jun 25;110(26):10806-11
references.pmid: 23754406
references.citation: Annu Rev Psychol. 2007;58:97-118
references.pmid: 17029564
references.citation: Proc Biol Sci. 2006 Feb 22;273(1585):417-23
references.pmid: 16615207
references.citation: Philos Trans R Soc Lond B Biol Sci. 2007 Apr 29;362(1480):649-58
references.pmid: 17301028
references.citation: Science. 2012 Mar 2;335(6072):1114-8
references.pmid: 22383851
references.citation: Proc Biol Sci. 2012 Feb 22;279(1729):715-21
references.pmid: 21831898
references.citation: Am J Phys Anthropol. 1966 Nov;25(3):305-14
references.pmid: 5971505
references.citation: Neuron. 2010 Mar 25;65(6):795-814
references.pmid: 20346756
references.citation: Trends Cogn Sci. 2010 Dec;14(12):552-60
references.pmid: 20971031
references.citation: Curr Biol. 2009 Nov 17;19(21):R995-R1008
references.pmid: 19922859
references.citation: Psychol Sci. 2004 Feb;15(2):94-9
references.pmid: 14738515
references.citation: Anim Behav. 2008 Aug;76(2):479-486
references.pmid: 19649139
references.citation: Annu Rev Psychol. 2008;59:279-300
references.pmid: 17550343
references.citation: Philos Trans R Soc Lond B Biol Sci. 2011 Apr 12;366(1567):1017-27
references.pmid: 21357224
references.citation: Proc Biol Sci. 1998 Oct 22;265(1409):1933-7
references.pmid: 9821360
references.citation: Proc Natl Acad Sci U S A. 2006 Nov 7;103(45):17053-7
references.pmid: 17075063
references.citation: Anim Cogn. 2009 Jan;12(1):181-92
references.pmid: 18716802
references.citation: Anim Cogn. 2005 Jul;8(3):164-81
references.pmid: 15549502
references.citation: Proc Biol Sci. 2005 Aug 22;272(1573):1641-6
references.pmid: 16087417
references.citation: Behav Brain Sci. 2008 Apr;31(2):109-30; discussion 130-178
references.pmid: 18479531
references.citation: Curr Biol. 2007 Aug 21;17(16):R714-23
references.pmid: 17714665
references.citation: Proc Natl Acad Sci U S A. 2010 Dec 14;107(50):21582-6
references.pmid: 21098277
references.citation: Trends Cogn Sci. 2009 Apr;13(4):148-53
references.pmid: 19285912
references.citation: Am J Phys Anthropol. 2003 Feb;120(2):171-81
references.pmid: 12541334
references.citation: Science. 2007 Oct 5;318(5847):107-9
references.pmid: 17916736
references.citation: BMC Biol. 2010 Jan 27;8:9
references.pmid: 20105283
references.citation: Am Nat. 2002 Dec;160(6):712-26
references.pmid: 18707460
references.citation: Anim Cogn. 2012 Sep;15(5):783-95
references.pmid: 22532073
references.citation: Proc Biol Sci. 2004 Aug 22;271(1549):1693-9
references.pmid: 15306289
references.citation: J Neurosci. 2013 Feb 20;33(8):3259-75
references.pmid: 23426655
references.citation: Philos Trans R Soc Lond B Biol Sci. 2007 Apr 29;362(1480):639-48
references.pmid: 17296598
references.citation: Philos Trans R Soc Lond B Biol Sci. 2007 Apr 29;362(1480):523-38
references.pmid: 17289649
references.citation: Proc Biol Sci. 2004 Jul 7;271(1546):1331-6
references.pmid: 15306330
references.citation: Brain Behav Evol. 2004;63(4):233-46
references.pmid: 15084816
references.citation: Proc Natl Acad Sci U S A. 2011 Feb 15;108(7):2693-8
references.pmid: 21262822
references.citation: Science. 1981 Jan 23;211(4480):341-50
references.pmid: 17748254
references.citation: Curr Biol. 2007 Dec 4;17(23):R1004-5
references.pmid: 18054758
references.citation: Proc Biol Sci. 2007 Feb 22;274(1609):453-64
references.pmid: 17476764
references.citation: Curr Opin Neurobiol. 2009 Feb;19(1):1-5
references.pmid: 19545995
references.citation: Anim Cogn. 2007 Jul;10(3):273-81
references.pmid: 17387529
references.citation: Biol Lett. 2006 Dec 22;2(4):557-60
references.pmid: 17148287
references.citation: J Exp Psychol Anim Behav Process. 1985 Jul;11(3):453-69
references.pmid: 4009126
references.citation: PLoS One. 2013 Jun 26;8(6):e66359
references.pmid: 23840450
references.citation: Proc Biol Sci. 2012 Oct 7;279(1744):4087-95
references.pmid: 22874748
references.citation: Brain Behav Evol. 2011;77(2):67-78
references.pmid: 21335939
references.citation: Nat Neurosci. 2008 Apr;11(4):426-8
references.pmid: 18344993
references.citation: Science. 2004 Dec 10;306(5703):1903-7
references.pmid: 15591194
references.citation: Anim Cogn. 2011 Jan;14(1):143-9
references.pmid: 20814805
references.citation: Philos Trans R Soc Lond B Biol Sci. 2012 Aug 5;367(1599):2097-107
references.pmid: 22734053
references.citation: J Pers. 2004 Apr;72(2):271-324
references.pmid: 15016066
references.citation: Prog Brain Res. 2012;195:71-87
references.pmid: 22230623
references.citation: Am Psychol. 1965 Jun;20:396-410
references.pmid: 14301944
references.citation: Proc Biol Sci. 2013 Mar 27;280(1759):20130269
references.pmid: 23536600
references.citation: PLoS One. 2012;7(12):e51918
references.pmid: 23284816
references.citation: Proc Biol Sci. 1996 Feb 22;263(1367):173-7
references.pmid: 8728982
references.citation: Proc Natl Acad Sci U S A. 2006 Nov 14;103(46):17568-73
references.pmid: 17079489
references.citation: J Cogn Neurosci. 1995 Winter;7(1):1-24
references.pmid: 23961750
references.citation: Nature. 1999 Oct 28;401(6756):877-84
references.pmid: 10553904
references.citation: Nature. 1981 Sep 3;293(5827):57-60
references.pmid: 7266659
references.citation: Science. 2006 Mar 3;311(5765):1297-300
references.pmid: 16513985
references.citation: Curr Biol. 2008 Sep 23;18(18):1415-9
references.pmid: 18804375
references.citation: Science. 2009 May 1;324(5927):646-8
references.pmid: 19407204
references.citation: Proc Natl Acad Sci U S A. 2007 Feb 27;104(9):3562-7
references.pmid: 17360682
references.citation: Proc Natl Acad Sci U S A. 2006 Sep 12;103(37):13606-11
references.pmid: 16938869
references.citation: Trends Cogn Sci. 2014 Feb;18(2):72-81
references.pmid: 24378542
references.citation: Proc Natl Acad Sci U S A. 1989 Feb;86(4):1388-92
references.pmid: 2919184
references.citation: Nature. 2004 Aug 12;430(7001):778-81
references.pmid: 15306809
references.citation: Front Hum Neurosci. 2009 Nov 09;3:31
references.pmid: 19915731
references.citation: J Comp Psychol. 2010 Aug;124(3):252-260
references.pmid: 20695656
references.citation: Science. 2007 Sep 7;317(5843):1360-6
references.pmid: 17823346
references.citation: Evol Anthropol. 2013 Sep-Oct;22(5):213-25
references.pmid: 24166922
references.citation: Science. 2007 Sep 7;317(5843):1344-7
references.pmid: 17823343
references.citation: Trends Ecol Evol. 1994 Jun;9(6):235-7
references.pmid: 21236837
references.citation: J Comp Neurol. 2009 Apr 10;513(5):532-41
references.pmid: 19226510
references.citation: Philos Trans R Soc Lond B Biol Sci. 2009 Nov 12;364(1533):3281-8
references.pmid: 19805434
references.citation: PLoS One. 2012;7(4):e32024
references.pmid: 22485130
references.citation: Dev Psychol. 1998 Sep;34(5):813-22
references.pmid: 9779730
references.citation: Trends Cogn Sci. 2008 May;12(5):187-92
references.pmid: 18424224
references.citation: Nature. 2006 May 18;441(7091):303
references.pmid: 16710411
references.citation: Anim Cogn. 2012 Mar;15(2):223-38
references.pmid: 21927850
references.citation: Am Nat. 2008 Jul;172 Suppl 1:S63-71
references.pmid: 18554145
references.citation: Anim Cogn. 2004 Oct;7(4):239-46
references.pmid: 15105996
references.citation: Science. 2002 Aug 9;297(5583):981
references.pmid: 12169726
references.citation: Philos Trans R Soc Lond B Biol Sci. 2007 Apr 29;362(1480):731-44
references.pmid: 17264056
references.citation: J Hum Evol. 2009 Oct;57(4):392-400
references.pmid: 19732937
references.citation: Brain Behav Evol. 2000 Jan;55(1):44-52
references.pmid: 10773625
references.citation: Cognition. 2008 Nov;109(2):224-34
references.pmid: 18849023
references.citation: Science. 1966 Jul 29;153(3735):501-6
references.pmid: 5938775
references.citation: Science. 1998 Oct 23;282(5389):746-9
references.pmid: 9784133
references.citation: J Hum Evol. 2009 May;56(5):471-8
references.pmid: 19410273
references.citation: Trends Cogn Sci. 2005 May;9(5):250-7
references.pmid: 15866152
references.citation: Proc Biol Sci. 2007 Oct 7;274(1624):2429-36
references.pmid: 17652066
references.citation: Philos Trans R Soc Lond B Biol Sci. 2012 Oct 5;367(1603):2794-802
references.pmid: 22927578
references.citation: Curr Opin Neurobiol. 1999 Apr;9(2):214-22
references.pmid: 10322177
references.citation: Proc Natl Acad Sci U S A. 2002 Apr 2;99(7):4436-41
references.pmid: 11891325
references.citation: Brain Behav Evol. 2007;70(2):115-24
references.pmid: 17510549
references.citation: Biol Lett. 2008 Jun 23;4(3):246-9
references.pmid: 18364305
references.citation: Trends Cogn Sci. 2005 Mar;9(3):118-25
references.pmid: 15737820
references.citation: Philos Trans R Soc Lond B Biol Sci. 2012 Aug 5;367(1599):2119-29
references.pmid: 22734055
references.citation: Sci Am. 1965 Jan;212:92-100
references.pmid: 14252463
references.citation: Trends Cogn Sci. 2007 Feb;11(2):65-9
references.pmid: 17188553
references.citation: Philos Trans R Soc Lond B Biol Sci. 2007 Apr 29;362(1480):561-75
references.pmid: 17255006
references.citation: Proc Natl Acad Sci U S A. 2005 Apr 12;102(15):5460-5
references.pmid: 15784743
references.citation: Front Evol Neurosci. 2012 Jan 03;3:11
references.pmid: 22319495
references.citation: Philos Trans R Soc Lond B Biol Sci. 2010 Sep 12;365(1553):2663-74
references.pmid: 20679110
references.citation: Science. 2004 Jun 11;304(5677):1682-3
references.pmid: 15192233
references.citation: Philos Trans R Soc Lond B Biol Sci. 1990 Aug 29;329(1253):153-60
references.pmid: 1978360
references.citation: Brain Behav Evol. 2002;59(1-2):10-20
references.pmid: 12097857
references.citation: Behav Brain Res. 2010 Dec 31;215(2):292-8
references.pmid: 19962409
references.citation: Curr Biol. 2007 Oct 9;17(19):1663-8
references.pmid: 17900899
references.citation: Proc Natl Acad Sci U S A. 2002 Apr 2;99(7):4141-2
references.pmid: 11929989
references.citation: Clin Psychol Rev. 2011 Nov;31(7):1209-23
references.pmid: 21889436
references.citation: Trends Cogn Sci. 2005 Jun;9(6):264-6
references.pmid: 15925802
references.citation: Anim Cogn. 2004 Jul;7(3):144-53
references.pmid: 14669075
references.citation: Proc Natl Acad Sci U S A. 2012 Jun 26;109 Suppl 1:10661-8
references.pmid: 22723358
references.citation: Evolution. 2007 Dec;61(12):2811-21
references.pmid: 17908248
references.citation: Philos Trans R Soc Lond B Biol Sci. 1985 Feb 13;308(1135):21-35
references.pmid: 2858875
references.citation: Psychol Rev. 2002 Jan;109(1):186-201
references.pmid: 11863037
references.citation: Behav Processes. 2009 Mar;80(3):210-7
references.pmid: 18824222
references.citation: J Commun Disord. 1999 Jul-Aug;32(4):251-69
references.pmid: 10466097
references.citation: Biol Lett. 2007 Oct 22;3(5):453-5
references.pmid: 17609175
references.citation: Psychol Bull. 2002 Sep;128(5):667-98
references.pmid: 12206190
references.citation: Science. 1989 May 26;244(4907):933-8
references.pmid: 2658056
references.citation: Science. 1985 Jul 19;229(4710):287-9
references.pmid: 9304205
references.citation: Science. 1995 Jun 16;268(5217):1578-84
references.pmid: 7777856
references.citation: Cognition. 1989 Apr;31(3):187-276
references.pmid: 2743748
references.citation: Science. 1975 May 16;188(4189):699-709
references.pmid: 17755167
references.citation: J Hum Evol. 2008 May;54(5):568-90
references.pmid: 18068214
references.citation: Am J Phys Anthropol. 2004 Jun;124(2):109-23
references.pmid: 15160365
references.citation: Biol Rev Camb Philos Soc. 2010 May;85(2):327-45
references.pmid: 19961472
references.citation: Philos Trans R Soc Lond B Biol Sci. 2012 Oct 5;367(1603):2715-22
references.pmid: 22927570
references.citation: Ann N Y Acad Sci. 2011 Apr;1225:191-9
references.pmid: 21535005