Peter Gärdenfors

1. Peter Gärdenfors The role of cooperation in the evolution of human communication

2. SEDSU project Stages in the Evolution and Development of Sign Use Work done in collaboration with Ingar Brinck and Mathias Osvath at Lund University

3. Hominin ancestors

4. What makes human thinking so unique?

5. Levels of Levels of cognition cooperation Levels of communication

6. Prospective cognition • ”Mental time travel” representing future needs and events • Involving ”detached” representations, suppressing current sensations • Unique in humans? (the Bischof-Köhler hypothesis) • Long ranging life style of hominins promoted prospective cognition

7. Oldowan tools ≈ 2.5 Mya

8. Main components of the Oldowan culture • Manufacturing and use of stone tools • Transport of artefacts (at least the stone tools) • Transport of pieces of carcasses • Use of accumulation spots • Division of labor (?) Plummer (2004): ”Flaked stones and old bones”, Yearbook of Physical Anthropology

9. Homo transportens

10. Intersubjectivity: Components of a ”theory of mind” • Understanding the emotions of others • Understanding the desires of others • Understanding the attention of others • Understanding the intentions of others • Understanding the beliefs of others

11. Representing the beliefs of others: False belief tasks 0. Subjects are three- to five-year-old children. 1. The children are first shown a Smarties tube and then asked what they think is in it. All the children reply “Smarties” (or “sweets”). 2. When the tube is opened it is found to contain pencils. 3. Then the tube is closed. 4. The children are now asked what a friend, who has not yet seen what is in the tube, will say that it contains. 5. The three-year-olds generally answer “pencils” whereas most of the older children say “Smarties.”

12. Levels of Levels of cognition cooperation Levels of communication

13. Ingroup vs. outgroup behaviour Reciprocal altruism Levels of cooperation

14. Reciprocalaltruism I scratch your back - you scratch mine Modeled by iterated prisoners’ dilemmas Building up trust between two individuals

15. Ingroup vs. outgroup behaviour Reciprocal altruism Cooperation about future goals Indirect reciprocity (the good Samaritan) Levels of cooperation

16. Building a reputation Nowak & Sigmund, 2005

17. Connections between cooperation, cognition and communication

18. Levels of Levels of cognition cooperation Levels of communication

19. Type of communication Most animal communication Mimesis Language Protolanguage (Tarzan) Language with syntax Basic levels of communication Type of sign (Peirce) • Signal (index) • Icon • Symbol

20. Communicating about our inner worlds

21. Why humans evolved symbolic communication • The Oldowan culture constituted an ecological niche containing evolutionary forces that fostered prospective cognition. • Prospective cognition made cooperation about future goals beneficial for the hominins. • Protolanguage is an efficient way of solving problems concerning cooperation about future non-existent goals.

22. Symbols are required for communication about future goals • If the goal is present, then signaling is sufficient.

23. Joint attention to a referent

24. Joint attention to a referent Future goal

25. Symbols are required for communication about future goals • If the goal is present, then signaling is sufficient. • If the communicated goal is not present, detached representations are required. Iconic miming may work, but only if the signaler and receiver have sufficient common knowledge about the goal. • If the communicated goal is a novel entity that does not yet exist, combinatorial symbols (protolanguage) are required. • Dessalles: Protolanguage can describe scenes. • Explains why no other species uses symbols.

26. Building a reputation Nowak & Sigmund, 2005

27. Indirect reciprocity requires language with (minimal) syntax Communication concerning reputation requires: • Reference to individuals in their absence • Express that “x was good to y” and “y was bad to x” • Express that “y has bad reputation” • Involves marking roles, which is done by syntax

28. Protolanguage is an efficient system for cooperation about future goals Language with syntax is an efficient system for maintaining indirect reciprocity Two hypotheses concerning the evolution of language

29. Possible archaeological evidence For prospective cooperation: • Division of labor • Big game hunting • Large dwellings • Marriage (Deacon) For indirect reciprocity: • Indications that reputation has social impact

30. Peter Gärdenfors The role of cooperation in the evolution of human communication

31. Representing the emotions of others: Empathy • Empathy: perception of emotion in another activates the same emotion in the receiver • Evidence for empathy in mammals • Speculation: depends on mirror neurons • Chimpanzees exhibit consolation behaviour • Cognitive empathy: subjects understand the emotions of others without having the emotion themselves

32. Representing the attention of others • Children at 6 months can follow the gaze of their mother if she turns her head • At 12 months they can follow the gaze of their mother if she just moves her eyes • At 18 months they can follow the gaze of their mother if she looks outside their field of vision (requires allocentric representation of space) • Chimps can also follow gazes in an allocentric way

33. Representing the intention of others Understanding the pursuit of goals: • Experiments where an adult (1) deliberately avoids handing over or (2) fails to hand over a reward (a toy or food) • Children from 9 months and chimps react differently to (1) and (2), i.e. to whether the failure was deliberate or not • Is this sufficient to claim that chimps represent the intentions of others?

34. How to avoid prisoners’ dilemmas • Iterated games (trust can be built up) • ”Guilt aversion” (Charness and Dufvenberg 2006) changes outcomes of a prisoners’ dilemma - increases cooperation • Presumes understanding desires • May explain egalitarianism in human (hominin) societies