Peter Gärdenfors

The role of cooperation in the evolution of human communication

SEDSU project

Stages in the Evolution and Development of Sign Use

Work done in collaboration with Ingar Brinck and Mathias Osvathat Lund University

Hominin ancestors

What makes human thinking so unique?

Levels of Levels of cognition cooperation

Levels ofcommunication

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

Oldowan tools ≈ 2.5 Mya

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

Homo transportens

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

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.”

Levels of Levels of cognition cooperation

Levels ofcommunication

Levels of cooperation

• Ingroup vs. outgroup behaviour

• Reciprocal altruism

Reciprocalaltruism

I scratch your back - you scratch mine

Modeled by iterated prisoners’ dilemmas Building up trust between two individuals

Levels of cooperation

• Ingroup vs. outgroup behaviour

• Reciprocal altruism

• Cooperation about future goals

• Indirect reciprocity (the good Samaritan)

QuickTime och enTIFF (okomprimerat)-dekomprimerare

krävs för att kunna se bilden.

Building a reputation

Nowak & Sigmund, 2005

Type of cooperation Cognitive demands Communicative demandsIngroup coperation Recognition of group member NoneReciprocal altruism(attitudinal reciprocity)

Individual recognition, minimalmemory, reacting to the desiresof others

None

Cooperation about futuregoals

Individual recognition, memory,prospective planning, valuecomparison, intersubjectivityincluding joint intentions

Symbolic communicationProtolanguage

Indirect reciprocity Individual recognition, (episodic)memory, slow temporaldiscounting, reacting to theemotions and intentions of others

Symbolic communicationLanguage with syntax forroles

Commitment andcontract

Individual recognition, memory,prospective planning, jointbeliefs

Symbolic communicationProtolanguage

Cooperation based onconventions

Intersubjectivity that allowscommon knowledge

None, but enhanced bysymbolic communication

Table 1: The cognitive and communicative demands of different forms of cooperation.

Connections between cooperation, cognition and communication

Levels of Levels of cognition cooperation

Levels ofcommunication

Basic levels of communication

Type of sign (Peirce)

• Signal (index)

• Icon

• Symbol

Type of communication• Most animal communication• Mimesis• Language

– Protolanguage (Tarzan)– Language with syntax

Communicating about our inner worlds

Why humans evolved symbolic communication

(1) The Oldowan culture constituted an ecological niche containing evolutionary forces that fostered prospective cognition.

(2) Prospective cognition made cooperation about future goals beneficial for the hominins.

(3) Protolanguage is an efficient way of solving problems concerning cooperation about future non-existent goals.

Symbols are required for communication about future goals

• If the goal is present, then signaling is sufficient.

Joint attention to a referent

Joint attention to a referent

Future goal

• 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.

Symbols are required for communication about future goals

Building a reputation

Nowak & Sigmund, 2005

Indirect reciprocity requires language with (minimal) syntaxCommunication 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

Two hypotheses concerning the evolution of language

• Protolanguage is an efficient system for cooperation about future goals

• Language with syntax is an efficient system for maintaining indirect reciprocity

Possible archaeological evidenceFor prospective cooperation:• Division of labor• Big game hunting• Large dwellings• Marriage (Deacon)

For indirect reciprocity:• Indications that reputation has social impact

Peter Gärdenfors

The role of cooperation in the evolution of human communication

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

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

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?

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