Population growth in excess of the productivity gains of the land has a fundamental effect on society’s structures. The typical changes accompa*nying population growth are high rents and land prices, increasing frag*mentation of peasant holdings or high numbers of landless peasants, and
increased migration of landless peasants to cities. Urbanization (measured by the proportion of population inhabiting towns and cities) increases.
Cheap labor results in a flowering of trades and crafts. The demand for manufactures increases, because the elites profit from high rents on land
and lower labor costs. Increased urbanization and conspicuous consumption by the elites promote regional and international trade. The gap be*
tween the well-to-do and the poor grows. In rural areas overpopulation means that no food reserves are available in case of crop failure. Accordingly, years of poor harvest that would hardly be noticed in better times now result in significant mortality and, at worst, in catastrophic famines. Chronic undernourishment creates conditions conducive to the spread of epidemics.

The cities accumulate landless peasants and jobless artisans, who join the growing ranks of paupers and vagrants. Food riots and wage protests
become frequent. Eventually, deepening economic misery leads to peasant and urban uprisings. However, as long as the elites are united and the
state maintains control of the military, such popular uprisings have small chance of success. This fundamental point was recently reiterated by
Jack Goldstone:

It is a profound and repeated finding that the mere facts of poverty and
inequality or even increases in these conditions, do not lead to political
or ethnic violence (Gurr 1980, Goldstone 1998, 2002b). In order for
popular discontent or distress to create large-scale conflicts, there must
be some elite leadership to mobilize popular groups and to create link*
ages between them. There must also be some vulnerability of the state
in the form of internal divisions and economic or political reverses.
Oth*erwise, popular discontent is unvoiced, and popular opposition is simply
suppressed. (Goldstone 2002a)

That sounds like stagflation. Despite increasing productivity, pressure on wages intensifies, and inequality intensifies.