Frequency Analyses of Historical and Archaeological Datasets Reveal the Same Pattern of Declining Sociocultural Activity in 9th to 10th Century CE Ireland

Abstract

This paper discusses how the production rate of historical and archaeological data might contain unique information about past societies. The case study is the frequency of entries in the Annals of Ulster, a primary early medieval source from Ireland, which was compared to the frequency of archaeological material from early medieval Ireland. The two datasets were found to contain similar trends, namely a rapid increase in activity in the 7 th Century, followed by a decline in the Early 9 th Century, low levels of activity in the 10 th Century, until recovery in the Late 10 th / Early 11 th Centuries. This overall pattern of activity had not been noticed before. Turning to the archaeological record of Britain, although there are certain similarities between Ireland and Scotland especially in the early part of the period, we find that the 9th and 10th centuries there were a stable period, and thus contrast with Ireland. We argue that environmental pressures are unlikely to be driving the signal, and instead various socio-cultural factors in the past coalesced in Ireland, leading to circumstances powerful enough to attenuate the enduring evidence for human activity, but expressing themselves silently, perhaps even in a way that was not immediately obvious to those witnessing them in the past. The simplest explanation, we contend, is that population levels fell throughout the period. This finding offers insight into the relationship between long-term change and the primary production of history, and supports the idea that the quantity of certain historical data can contain information about past realities.

Evaluating Bayesian radiocarbon-dated event-count [REC] models for the study of long-term human and environmental processes

“…The underlying logic is based on a correlation between organic carbon deposition and a given past process of interest. In archaeology, the process most often under investigation is population level change (e.g., Armit et al, 2013;Bamforth and Grund, 2012;Collard et al, 2010;Colledge et al, 2019;Faulkner, 2011;Gamble et al, 2005;Hannah and McLaughlin, 2019;Leipe et al, 2019;Lepofsky et al, 2005;Mclaughlin et al, 2018;Prentiss et al, 2014;Schulting, 2010;Shennan, 2013;Steele, 2010;Turney and Brown, 2007). Spatio-temporal variation in human population levels is thought to be related to variation in organic carbon deposition because certain human activities lead to concentrations of organic carbon in sediment and those activities occur more often when and where there are more people present.…”

“…This is not necessarily a problem if, following Bronk Ramsey (2017), the proxy is only interpreted as the temporal distribution of the total chronological information in a radiocarbon dataset. The desired proxy in most cases, however, is the number of events that occurred in each interval of a sequence (e.g., Broughton and Weitzel, 2018;Hoffmann et al, 2008;Mclaughlin et al, 2018) and the SPDF cannot isolate that number from chronological uncertainty about the timing of the individual events.…”

Sum things are not what they seem: Problems with point-wise interpretations and quantitative analyses of proxies based on aggregated radiocarbon dates

“…Archaeologists have been particularly enthusiastic, routinely using radiocarbon dates as a proxy for past population levels (e.g. Armit et al, 2013; Collard et al, 2010; Colledge et al, 2019; Faulkner, 2011; Gamble et al, 2005; Hannah and McLaughlin, 2019; Leipe et al, 2019; Lepofsky et al, 2005; Mclaughlin et al, 2018; Prentiss et al, 2014; Schulting, 2010; Shennan, 2013; Steele, 2010; Turney and Brown, 2007).…”

Evaluating Bayesian Radiocarbon‐dated Event Count (REC) models for the study of long‐term human and environmental processes

“…In archaeology, the target process is often population‐level change (e.g. Gamble et al ., 2005; Lepofsky et al ., 2005; Turney and Brown, 2007; Collard et al ., 2010; Schulting, 2010; Steele, 2010; Faulkner, 2011; Armit et al ., 2013; Shennan, 2013; Prentiss et al ., 2014; Mclaughlin et al ., 2018; Colledge et al ., 2019; Hannah and McLaughlin, 2019; Leipe et al ., 2019). Spatio‐temporal variation in human population levels is thought to be related to variation in organic carbon deposition because certain human activities lead to concentrations of organic carbon in sediment and those activities occur more often when and where there are more people present.…”

“…The desired proxy in most cases, however, is the number of events that occurred in each interval of a sequence (e.g. Hoffmann et al ., 2008; Broughton and Weitzel, 2018; Mclaughlin et al ., 2018) and the SPDF cannot isolate that number from chronological uncertainty about the timing of the individual events.…”