Language — the most distinctive human trait — remains a ‘mystery’(Knight, Studdert-Kennedy, & Hurford, 2000) or even a ‘problem’(Hauser et al., 2014) for evolutionary theory. It is underpinned by cooperative turn-taking (Sacks, Schegloff, & Jefferson, 1974), which has been implicated with highly sophisticated cognitive skills such as mindreading (Tomasello, 2008). Some have claimed that this turn-taking system is uniquely human (Melis, Grocke, Kalbitz, & Tomasello, 2016; Yamamoto & Tanaka, 2009), but others argue that it provides the evolutionary ‘missing link’ between animal and human communication (Levinson & Holler, 2014). This debate has been constrained by a lack of comparative data, methodological confounds that often prevent meaningful comparisons, and a lack of information on key components of social relationships (Cords & Aureli, 2000; Fraser, Schino, & Aureli, 2008) that might strongly impact upon turn-taking propensities.
Objectives: TURNTAKING will quantify turn-taking production and comprehension in human children, chimpanzees, and two distantly related species — geladas and common marmosets. It will apply a powerful combination of systematic behavioral observations, eye-tracking paradigms, and established measures from Conversational Analysis(Sacks et al., 1974; Schegloff, 2007) and Primatology(Fraser et al., 2008) that allow the same type of data to be collected and analyzed in directly comparable ways across species. This will provide the first rigorous test of whether cooperative turn-taking is uniquely human, ancestral in the primate lineage, or evolved independently in different species. TURNTAKING will identify which hallmarks of human turn-taking are shared across different primate species, and which key components of relationship quality (Cords & Aureli, 2000; Fraser et al., 2008) act upon turn-taking skills.
Outcomes: This project will found the field of comparative turn-taking, and provide pioneering insights into the behavioral flexibility underlying different turn-taking systems. It will go beyond the state of the art by exposing whether cooperative turn-taking is the evolutionary ‘missing link’ between our species and our inarticulate primate cousins, and whether pro-social behaviors drove its emergence.
