  Cumulative cultural evolution occurs when adaptive innovations are passed
down to consecutive generations through social learning. This process has
shaped human technological innovation, but also occurs in non-human species.
While it is traditionally argued that cumulative culture relies on
high-fidelity social transmission and advanced cognitive skills, here I show
that a much simpler system suffices. Cumulative culture spontaneously emerged
in artificial agents who navigate with a minimal cognitive architecture of
goal-direction, social proximity, and route memory. Within each generation,
naive individuals benefitted from being paired with experienced navigators
because they could follow previously established routes. Crucially, experienced
navigators also benefitted from the presence of naive individuals through
regression to the goal. As experienced agents followed their memorised path,
their naive counterparts (unhindered by route memory) were more likely to err
towards than away from the goal, and thus biased the pair in that direction.
This improved route efficiency within each generation. In control experiments,
cumulative culture was attenuated when agents' social proximity or route memory
were lesioned, whereas eliminating goal-direction only reduced efficiency.
These results demonstrate that cumulative cultural evolution occurs even in the
absence of sophisticated communication or thought. One interpretation of this
finding is that current definitions are too loose, and should be narrowed. An
alternative conclusion is that rudimentary cumulative culture is an emergent
property of systems that seek social proximity and have an imprecise memory
capacity, providing a flexible complement to traditional evolutionary
mechanisms.
