constant.
In Europe, during the period 650-1350, there was a steady, relatively gradual, but very substantial increase of population, perhaps doubling between 650 and 1000, then doubling again by 1350. The pattern of this increase strongly suggests that the reason for this population increase was economic growth, adding to the productive resources available to the European population.
It is true that 650 was at the end of a long period of political, economic, and demographic decline, so that Europe was underpopulated relative to its productive potential. We might then suppose that the population increase was simply a population expanding to its Malthusian limit. However, population growth of this type ("free land for the taking") can be very rapid. The population of England, for example, doubled in the 16th century, in effect making good the losses from and following the Black Plague 200 years earlier.
The trend of population growth in Etrope was much more gradual than we would expect from a filling-out to exploit readily available but untapped resources. It is a trend consistent, in fact, not with unchecked Malthusian population growth, but with the more gradual and steady growth of productive resources. Indeed, whatever land had gone fallow since Roman times was by 650 likely to have fully reverted to its natural condition. It thus was a wilderness that had to be broken to cultivation anew.
A variety of other evidence supports the contention of economic growth during this period. Enormous tracts that were forested in the 7th century, and even in 1000, had been transformed into farmland by 1350. Technology had also progressed. The heavy moldboard plow allowed working land that could not be used effectively in Roman times, while the three-field system increased productivity per hectare of farmland. Other technologies make an appearance; windmills and water mills proliferate across the landscape from the 11...