in good times it was barely able to feed its population. Grain yields in the 14th century were between 2:1 and 7:1 (2:1 means for every seed planted, 2 are harvested. Modern grain yields are 30:1 or more.) Malnutrition developed gradually over decades, lowering resistance to disease, and competition for resources meant more warfare, and then finally crop yields were pushed down by the Little Ice Age. An alternative theory is that competition for resources exacerbated the imbalance between property-owners and workers. and that the money supply ceased to keep up with fixed increased economic activity (being commodity money based principally on silver) so that wages sank while rents rose, leading to demographic stagnation. The economic conditions of the poor also aggravated the calamities of the plague because they had no recourse, such as fleeing to a villa in the country in the manner of the nobles in the Decameron. The poor lived in crowded conditions and could not isolate the sick, and had weaker immunities from a deficient diet, difficult living and working conditions and poor sanitation. After the plague and other exogenous causes of population decline lowered the labor supply, wages increased. This increased the mobility of labour and led to a redistribution of wealth, although property-owners' attempts to resist change through wage freezes and price controls contributed to popular uprisings such as the Peasants' Revolt of 1381. By 1450, the total population of Europe was substantially below that of 150 years earlier, but all classes overall had a higher standard of living. The Brenner Debate Still yet another theory, as introduced by Robert Brenner in a 1976 paper, is that the economic system of the High Middle Ages limited population growth. Feudal lords and landlords controlled most of Europe’s land; they could charge high enough rents or demand a large enough percentage of peasants' profit that peasants on these lands were forced to survive at subsistence levels. With any surplus of food, labor, and income absorbed by the landowners, the peasants did not have enough capital to invest in their farms or enough incentive to increase the productivity of their land. In addition, the small size of most peasants' farms inhibited centralized and more efficient cultivation of land on larger fields. In regions of Europe where primogeniture was less widely practiced, peasant lands were subdivided and re-subdivided with each generation of heirs; Brenner writes that consequently: "This