The Neolithic Demographic Transition in Europe: Correlation with Juvenility Index Supports Interpretation of the Summed Calibrated Radiocarbon Date Probability Distribution (SCDPD) as a Valid Demographic Proxy

Abstract

Analysis of the proportion of immature skeletons recovered from European prehistoric cemeteries has shown that the transition to agriculture after 9000 BP triggered a long-term increase in human fertility. Here we compare the largest analysis of European cemeteries to date with an independent line of evidence, the summed calibrated date probability distribution of radiocarbon dates (SCDPD) from archaeological sites. Our cemetery reanalysis confirms increased growth rates after the introduction of agriculture; the radiocarbon analysis also shows this pattern, and a significant correlation between both lines of evidence confirms the demographic validity of SCDPDs. We analyze the areal extent of Neolithic enclosures and demographic data from ethnographically known farming and foraging societies and we estimate differences in population levels at individual sites. We find little effect on the overall shape and precision of the SCDPD and we observe a small increase in the correlation with the cemetery trends. The SCDPD analysis supports the hypothesis that the transition to agriculture dramatically increased demographic growth, but it was followed within centuries by a general pattern of collapse even after accounting for higher settlement densities during the Neolithic. The study supports the unique contribution of SCDPDs as a valid demographic proxy for the demographic patterns associated with early agriculture.

Culture Process and the Interpretation of Radiocarbon Data

“…Archaeologists increasingly use large samples of 14 C dates to estimate human population sizes, long-term population growth rates, and other demographic processes (e.g., Pettitt et al 2003;Shennan 2008;Peros et al 2010;Williams 2012Williams , 2013Kelly et al 2013;Shennan et al 2013;Contreras and Meadows 2014;Wang et al 2014;Crema et al 2016;Zahid et al 2016). Making inferences from these data sets about demography, however, is not without challenges (Williams 2012;Downey et al 2014;Attenbrow and Hiscock 2015;Brown 2015Brown , 2017. The issues stem from processes external and internal to prehistoric human populations.…”

“…These studies constitute invaluable frames of reference for making more informed inferences about demographic processes from the frequency of 14 C date time-series. However, less attention has been paid to the ways that cultural process, internal to prehistoric populations, may affect the creation of the 14 C record (but see Downey et al 2014). …”

Reproductive trade-offs in extant hunter-gatherers suggest adaptive mechanism for the Neolithic expansion

“…It has been suggested that cultivation increased calorie availability which, combined with a reduction in energy expenditure resulting from sedentarization, led to increased energy availability for reproduction (8)(9)(10). As a result, although exact estimates vary, it has been argued that average population growth rates rose from <0.001% to ∼0.04% per year during the early Neolithic (6,8,(11)(12)(13)(14)(15)(16)(17).…”

European Neolithic societies showed early warning signals of population collapse

“…This site-based population proxy assumes that the temporal frequencies of occupied human settlements in a given region index relative human population size. Use of SPD-based approaches to inferring population change has been debated in the literature (18)(19)(20)(21)(22)(23)(24)(25)(26). Critics have raised concerns about confounding factors including atmospheric effects, sampling biases, taphonomic processes, or calibration error; however, the methods used here and elsewhere (20) attempt to control for these sources of error by (i) correcting systematic biases in the data and (ii) comparing the corrected empirical patterns to null SPD models that simulate exogenous processes.…”