A paper from 2007 (PDF) explains some of the negative civilizational developments that we have been observing over the last decade. And events quite clearly appear to have proven his thesis largely correct.
The Population Cycle Drives Human History – from a Eugenic Phase into a Dysgenic Phase and Eventual Collapse
by Volkmar Weiss
In the period before the onset of demographic transition from large to small families, when fertility rates were positively associated with income levels, Malthusian pressure gave an evolutionary advantage to individuals whose characteristics were positively correlated with child quality and hence higher IQ, increasing in such a way the frequency of underlying genes in the population. As the fraction of individuals of higher quality increased, technological progress intensified. Positive feedback between technological progress and the level of education reinforced the growth process, setting the stage for an industrial revolution that facilitated an endogenous take-off from the Malthusian trap. The population density rose and with it social and political friction, especially important at the top of the social pyramid. Thus, from a certain turning point of history, the well-to-do have fewer children than the poor.
Once the economic environment improves sufficiently, the evolutionary pressure weakens, and on the basis of spreading egalitarian ideology and general suffrage the quantity of people gains dominance over quality. At present, we have already reached the phase of global human capital deterioration as the necessary prerequisite for a global collapse by which the overpopulated earth will probably decimate those of mediocre IQ.
On the one hand, this will present opportunities for the cognitive elite. On the other, the downward trajectory of society and civilization is almost certainly going to increase as time goes on, IQ continues to decline, and the r/selected increasingly outnumber the K/selected. The welfare system was bad enough, but combining it with low-quality mass immigration is fatal. The longer the negative cycle persists, the more likely it is that the people of the West will eventually have to choose between utterly ruthless eugenics and total civilizational collapse.
When we look at the history of past high civilisations, it is noticeable that it was a long time before internal decay lead to final collapse (Knaul, 1985). From a certain point on there were nearly only failures. The economy stagnated and the finances of the state and of the cities fell more and more into disorder. The number of people depending on welfare rose from year to year, although each new ruler declared it an aim to lower this number. The security of the citizens was no longer guaranteed; the relationship between man and woman had likewise changed as had the relationship between young and old. The whole society seemed to be stricken by an illness and incapable of making and implementing rational and necessary decisions. Although nobody wanted the decline, the states and their inhabitants accepted policies that steered themselves into an abyss in such a way, as though they had no other goal than falling into the abyss. Today, our situation is similar.