Neolithic Demographic Transition - Prehistoric Baby Boom

A Population Boom at the Dawn of Farming

Reconstructed Linearbandkeramic Farmhouse, Archeon
Reconstructed Linearbandkeramic Farmhouse, Archeon. Hans Splinter

The Neolithic Demographic Transition (abbreviated in the literature, thank goodness, as NDT and sometimes called the Agricultural Demographic Transition) is a theory that argues that one effect of the human transition in subsistence methods (how we feed ourselves) from foraging to farming is an increase in the average number of children we have. That increase in the total fertility rate is estimated at a whopping two births per woman over a period of two to three hundred years.

That growth, says the theory's authors, was the direct result of the energy gain of high-calorie food of sedentary farmers (wheat, lentils, peas, maize, rice or millet, depending on where you live) compared to that of mobile hunter-gatherers (mainly meat), coupled with a decrease in energy expended moving around chasing food.

Roots of the NDT

The theory arose from the early 21st century investigations of French paleontologist Jean-Pierre Bocquet-Appel, on Mesolithic and Neolithic cemeteries in Europe and North Africa, including but not limited to Linearbandkeramic groups. What those studies found was that in cemeteries dated to the 500-700 years when people transitioned from hunting and gathering to farming, there was a relatively abrupt increase in the proportion of juveniles (individuals aged 5-19 years of age), in some cases as much as 20-30% more.

Such an increase doesn't just mean that more people died young, it means that more children were being born: there was a significant increase in the number of children being born just when people settled into villages and started to grow their own crops.

Calculating Crude Birth Rate

Bocquet-Appel and his colleagues used "big data" concepts, and conducted an in-depth search of the literature on cemeteries in North Africa and Europe during the Mesolithic and Neolithic periods. They were interested in demographic patterns, how many people died at what age in different sites and places, as a measure of health.

The patterns they were looking for involved an unconventional measure, based on the distribution of skeletons by age, and represented by the proportion of immature individuals aged 5-19.

They chose to look for individuals in this age bracket because that statistic is a marker of population growth or decline: in a growing [living] population, the percentage of people aged 0-19 is high; in a declining population, the percentage is low. Bocquet-Appel wanted to know if that was reflected in prehistoric cemeteries. It might seem counter-intuitive: doesn't more people in the cemetery mean more people are dying? That's true, but if the cemetery does not represent a catastrophic event, its population also reflects the proportions of the living community.

The European and North African Neolithic

The original investigation involved 68 Mesolithic and Neolithic cemeteries, selected if (1) there was adequate usable data; (2) if the cemetery represented a single culture or could be divided into separate cultures; (3) the cemetery could be absolutely or relatively dated; (4) the cemetery did not represent catastrophic events; and (5) at least 50% of the cemetery had been excavated.

What Bocquet-Appel and colleagues saw when they crunched the numbers was an abrupt, significant increase in the proportion of juvenile individuals in overall populations at the time of the subsistence shift from hunting and gathering to farming.

Populations transitioning to farming clearly experienced a population boom within a couple of centuries.

Beyond Europe and North Africa

Since the original study in 2002, various scholars have looked beyond Europe and North Africa, and have identified the same pattern of transition to a higher birth rate at the Neolithic transition, in East and Southeast Asia (Bellwood and Oxenham), in North America (Bocquet-Appel 2011, Kohler, Wills), in Southwest Asia (Kuijt, fort et al), in North and South China, in Ethiopia, in Mesoamerica and in South America--in fact, everywhere it has been looked for. In all these areas, the rise in growing foods is accompanied by a rise in growing children. The expansion of Bocquet-Appel's thesis into these areas requires that the NDT now be called the Agricultural Demographic Tradition.

The growth in population, particularly when it involves living in close proximity to other people, is not all good of course, and scholars researching the NDT have noticed a menacing increase in endemic infectious diseases, everything from childhood mumps and measles to bubonic and other plagues. But that is another story.

Sources

This article is a part of the About.com guide to the Origins of Agriculture, and the Dictionary of Archaeology.

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Bocquet-Appel J-P, and Dubouloz J. 2004. Expected palaeoanthropological and archaeological signal from a Neolithic demographic transition on a worldwide scale. Documenta Praehistorica 31:25-33.

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