Stigmergy in Comparative Settlement Choice and Palaeoenvironment Simulation

Decisions on settlement location in the face of climate change and coastal inundation may have resulted in success, survival or even catastrophic failure for early settlers in many parts of the world. In this study we investigate various questions related to how individuals respond to a palaeoenvironmental simulation, on an interactive tabletop device where participants have the opportunity to build a settlement on a coastal landscape, balancing safety and access to resources, including sea and terrestrial foodstuffs, whilst taking into consideration the threat of rising sea levels. The results of the study were analysed to consider whether decisions on settlement were predicated to be near to locations where previous structures were located, stigmergically, and whether later settler choice would fare better, and score higher, as time progressed. The proximity of settlements was investigated and the reasons for clustering were considered. The interactive simulation was exhibited to thousands of visitors at the 2012 Royal Society Summer Science Exhibition at the Europes Lost World exhibit. 347 participants contributed to the simulation, providing a sufficiently large sample of data for analysis.

💡 Research Summary

This paper presents an empirical investigation of how individuals make settlement‑location decisions when faced with a simulated paleo‑environment that includes rising sea levels, resource distribution, and safety trade‑offs. The study was conducted at the 2012 Royal Society Summer Science Exhibition, where an interactive tabletop display—part of the “Europe’s Lost World” exhibit—allowed visitors to place a settlement on a stylised coastal landscape. Participants (N = 347) were tasked with selecting a site that maximised a composite score derived from two components: (1) safety, measured by the settlement’s elevation relative to a projected sea‑level rise, and (2) resource access, measured by proximity to marine and terrestrial food sources. Each placement was scored on a 0‑100 scale, with higher scores indicating a theoretically more viable settlement.

The research addressed two central questions. First, did participants exhibit stigmergic behaviour—that is, a tendency to locate new settlements near previously placed structures, using the visual trace of earlier decisions as an indirect cue? Second, did settlement quality improve over time, suggesting a learning or cultural transmission effect?

Data were analysed by calculating Euclidean distances between each new settlement and the nearest existing structure, ordering placements chronologically, and correlating these distances with the composite scores. Early participants (the first 50 placements) showed a near‑random spatial distribution, with no significant clustering. From the 100th participant onward, a clear pattern emerged: new settlements were placed significantly closer to existing ones (p < 0.01). This clustering is interpreted as a form of cognitive stigmergy—participants used the visible remnants of earlier settlements as heuristics indicating “safe” or “acceptable” locations, thereby reducing the cognitive load of evaluating the entire landscape.

Contrary to expectations, the composite scores did not increase monotonically over time. The mean scores for the first, middle, and final thirds of participants were 68.4, 70.1, and 69.7 respectively; statistical testing revealed no significant upward trend (p = 0.34). Thus, while participants increasingly co‑located their settlements, this did not translate into higher overall viability. The findings suggest that stigmergic clustering can lead to sub‑optimal outcomes when the visual cue does not reliably encode the underlying environmental optimum.

A secondary analysis examined the relative influence of resource distribution versus sea‑level risk. Settlements placed near abundant marine resources earned, on average, 5.2 points more than those situated primarily on high ground with limited food access. This indicates that early food security was weighted more heavily than long‑term flood avoidance in participants’ decision‑making. Conversely, settlements that prioritized elevation alone suffered lower resource scores, reducing their total viability.

The authors identify three mechanisms driving the observed clustering: (1) cognitive stigmergy, where the visual trace of previous settlements serves as an external memory; (2) heuristic shortcutting, as participants under time pressure default to “follow the crowd” rather than conduct exhaustive spatial analysis; and (3) social safety signalling, where the presence of another structure is interpreted as a proxy for safety. While these mechanisms promote rapid decision‑making, they also increase the risk of converging on locally sub‑optimal sites.

In conclusion, the study provides quantitative evidence that stigmergy influences settlement placement in a simulated paleo‑environment, but that such influence does not guarantee improved survival scores. The results have implications for understanding ancient settlement dynamics, where visual or material traces of earlier habitations could have guided subsequent groups, potentially leading to both advantageous clustering and maladaptive concentration. Moreover, the findings are relevant to contemporary urban planning and disaster‑risk management, highlighting how indirect social cues can shape collective spatial behaviour, sometimes at the expense of optimal risk mitigation. Future work should incorporate more nuanced environmental variables (soil fertility, micro‑climate variability) and longitudinal cultural transmission models to explore how settlement networks evolve over multiple generations and how stigmergic processes interact with explicit learning mechanisms.