marjaerwin

I've done a bit of demographic research, mostly on the Mediterranean and Europe. Anyway, typical estimates of life expectancy:

Hellas, 330s B.C.E.: 25 years. (Mogens Herman Hansen, The Shotgun Method, p. 55.)

England, 1270s: 25 years. (Quoted in Ole Benedictow, The Black Death, p. 252.)

Europe, 1390s to 1540s: 20-25 years. (Benedictow, p. 251.)

Norway, 1660s: <26 years. (Benedictow, p. 250.)

France, 1700: 25 years. (Benedictow, p. 250.)

Norway, 1750s, 35 years. (Benedictow, p. 250.)

France, 1780s: 29 years. (Benedictow, p. 250.)

India, 1911: 22-24 years under colonialism. (Benedictow, p. 250.)

Of course, Europe had a particularly bad disease environment. It's quite likely that the Americas had on the whole a higher life expectancy, before European colonization, smallpox, and other European diseases. I don't know how to eveluate the sources available; some papers suggest 20 years, but that's worse than Europe, when the disease environment was better than Europe, so that seems less-than-trustworthy. I just don't see how it's racist or colonialist to think in terms of 40 years instead of 80 years.

Walter Scheidel, in his 2007 working paper “Roman population size: the logic of the debate” notes that the best reconstructions of Roman population distribution seem to clash with the best reconstructions of medieval and early modern population distribution. He presents the following estimates:

Peninsular Italy:

4.5 million to 5.5 million in the 1st Century CE (low count)
4.1 million to 5.0 million in the 13th Century CE

Cisalpine Gaul

1.5 million to 2.5 million in the 1st Century CE (low count)
6.0 million to 7.0 million in the 13th Century CE (?)

Higher population counts leave the distribution problem unresolved, and create other problems. Scheidel considers this one of the major problems in understanding the demography of the Roman world.

His working papers are online at http://www.princeton.edu/~pswpc/papers/authorMZ/scheidel/scheidel.html

It's fascinating, but I think Leslie White was three-quarters right with his plow theory. He argued that the heavy plow was introduced in the 6th and 7th Centuries, revolutionizing northern European agriculture, and spreading Slavic language and culture with the technology. In fact, the heavy plow incorporated new technologies, such as the coulter and the mouldboard, which developed over the entire 1st Millennium CE.

Although this probably misses much of the complexity of the issue, I think it makes sense to distinguish two agricultural traditions:

An older agriculture, which developed before the 1st Millennium CE, which was adapted to lighter soils, which used lighter plows, square fields, and two-field farming.

A newer agriculture, which developed during the 1st Millenium CE, which would adapt to heavier soils, which would develop heavier plows, strip fields, and in its later version three-field farming.

If we look at soil maps, it's clear that most arable land – excepting very rocky soils – in mediterranean Europe consists of alluvial soils and relatively light soils. Most arable land in northern Europe consists of heavy soils, including forest soils and wetland soils. About two-thirds of the arable land in Cisalpine Gaul had forest soils.

Some loess soils were accessible to the older agriculture, but most northern European soils – and Cisalpine Gallic soils – were marginal or inaccessible to the older agriculture. As the newer agriculture developed, it seems to have allowed increased settlement density in the intermediate soils, and gradual colonization of the heavier soils.

Pre-Roman and Roman settlement was generally concentrated in alluvial soils and other light soils. But, for example, Chernyakhov-culture settlement was generally concentrated near intermediate forest soils, such as those of Bukovina, circling the Carpathians and north of the Balkan mountains – as in the settlements outside Nicopolis, at Gradishte, and at Veliki Preslav.

When the newer agriculture was beginning to develop, it allowed increased settlement of intermediate soils, such as the Gothic settlement of Bukovina; as it continued to develop, it allowed increased settlement of heavy soils, such as the Slavic settlement of the Black Earth.

The newer agriculture allowed a population explosion in northern Europe – perhaps doubling or tripling between the 1st and 4th Centuries and doubling or tripling again between the 4th and 10th Centuries. But the newer agriculture disrupted existing field systems and, by opening new land to settlement, weakened established landlords and, it would seem, emperors.