Transition
to agriculture triggered demographic growth followed by collapse
Researchers have used two sets of
data from the period 6000 to 2000 BC to investigate the demographics of the
transition to agriculture in Europe: data from cemeteries, and radiocarbon
dates from 24 well-documented archaeological regions across Europe.
The juvenility index is the
proportion of a population aged between 5 and 19 years old: in an increasing
population, this is high; in a declining population it is low. Researchers obtained
data from 212 cemeteries, weighting results by settlement size. They then considered
the Summed Calibrated Radiocarbon Date Probability Distribution (SCDPD) of 8,032
radiocarbon dates, which can be used as a proxy for population density and
indicate whether populations are rising or falling at a given time.
Both sets of data gave similar
results. The transition from Mesolithic to Neolithic in each region was
accompanied by a sharp increase in the population, but after a period of stability
there was a decline. The cemetery data indicated a period of growth lasting for
about 720 years, a period of stability lasting for just under 1,000 years,
followed by a decline. The use of radiocarbon dates is less proven as a proxy,
but because far more data is available it should provide higher resolution
results. The radiocarbon dates indicated that the period of growth had lasted
for 420 years before a decline set in, lasting for 840 years for a complete
boom to bust cycle of 1,260 years. That the two sets of results are reasonably
consistent confirms SCDPD as a valid demographic proxy.
References:
1. Downey, S., Bocaege,
E., Kerig, T., Edinborough, K. & Shennan, S., Correlation with Juvenility
Index Supports Interpretation of the Summed Calibrated Radiocarbon Date
Probability Distribution (SCDPD) as a Valid Demographic Proxy. PLoS One 9
(8), e105730 (2014).
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