Greater than the sum of its parts? Modelling population contact and interaction of cultural repertoires

Abstract

Evidence for interactions between populations plays a prominent role in the reconstruction of historical and prehistoric human dynamics; these interactions are usually interpreted to reflect cultural practices or demographic processes. The sharp increase in long-distance transportation of lithic material between the Middle and Upper Palaeolithic, for example, is seen as a manifestation of the cultural revolution that defined the transition between these epochs. Here, we propose that population interaction is not only a reflection of cultural change but also a potential driver of it. We explore the possible effects of inter-population migration on cultural evolution when migrating individuals possess core technological knowledge from their original population. Using a computational framework of cultural evolution that incorporates realistic aspects of human innovation processes, we show that migration can lead to a range of outcomes, including punctuated but transient increases in cultural complexity, an increase of cultural complexity to an elevated steady state and the emergence of a positive feedback loop that drives ongoing acceleration in cultural accumulation. Our findings suggest that population contact may have played a crucial role in the evolution of hominin cultures and propose explanations for observations of Palaeolithic cultural change whose interpretations have been hotly debated.

Cultural Selection Shapes Network Structure

“…Due to the increased number of individuals learning and innovating along the same traits, trait proficiency increases. These dynamics can be interpreted as an increase in the 'e ective cultural population size' (for a few traits) which has been suggested as the main driver of the transition between Middle and Upper Palaeolithic, marked by an increase technological complexity but also by increased inter-connectedness between groups 56 . Consistent with our results, archaeological analysis suggests that increased inter-group connectedness lead to decreased technological volatility 57 .…”

The evolutionary advantage of cultural memory on heterogeneous contact networks

“…On the contrary, if subsets of the population worked separately and then compared their solutions, this partially connected network produced a diversity of perspectives that often produced better combined results than completely connected populations (Derex and Boyd, 2016). Creanza et al (2017b) analyzed spatially structured populations from another perspective, modeling a set of separate populations with their own cultural repertoires and allowing these populations to interact through migration. These migration events between populations produced bursts of innovations that increased the cultural repertoires of populations that received migrants.…”

High-magnitude innovators as keystone individuals in the evolution of culture

“…[9–17]), as well as on the diffusion of innovations [18–20]. Lately, a series of models turned the spotlight onto the way different types of innovations may shape the evolution of culture [21–23]. The different nature that innovations may have pertains to a longstanding dispute in the animal behaviour literature.…”

“…Thus, high-magnitude innovations allow copiers of the innovation to explore a new domain and perhaps modify it by innovating themselves. Models focusing on the effect of different innovation types on human cultural evolution have utilized the latter idea, suggesting to account for the punctuated evolutionary pattern found in the human artifact archeological record [21–23]. High-magnitude innovators may therefore not only serve as keystone individuals by generating cultural leaps, but also by facilitating socially induced innovations, that further modify their own.…”