Semiotic Evolution of Toolmaking: the Role of Symbols for Work towards Delayed Reward

Tools depend on mental models that mediate their construction by way of motor acts. Given that tools are signs of semiotic behavior, the semiotic characterization of Neolithic weapon production has the potential to elucidate the broad cognitive processes underlying the origins of tool-making. Spatio-temporal corelation is the defining property of indexes, while laws characterize symbols. Stones picked and thrown at a prey or predator can instantaneously index fight and social rank, but carefully manufactured stone weapons, which require elaborate and tiring work over extended periods of time, require by necessity the symbolic association of complex motor habits with anticipatory images of successful tool use, i.e. specific classes of effects such as prey chase, kill, transportation, preparation, sharing and eating. Reward-related symbolization during tool manufacture would allow for active mnemonic traces in the cerebral cortex and hippocampus to engage limbic circuits related to emotion and reward seeking. This would provide the motivation required for work towards a distant goal, leading to the sustained and repetitive activation of motor cortex and striatum. Additional symbolization at the level of gestures, postures, vocalizations, sand drawing and wall painting were the likely waking motivators of Neolithic weapon making, in addition to dreams depicting the hunting act and the associated symbols. We propose that Neolithic tool-making would have been impossible without symbolization.