* '''Atheism''': Most human societies have also been highly religious,<ref>https://www.gwern.net/docs/psychology/1991-brown-humanuniversals.pdf</ref> whereas modern civilizations are highly atheistic. Atheism tends to imply lower birth rates.<ref>https://link.springer.com/article/10.1007/s10680-015-9371-z</ref>
* '''Behavioral sink''': Other mismatches may be overpopulation, an aging population or even the rise of [[mutation]]s and disruption of social epistasis (see [[behavioral sink]]).
* '''No responsibility''': Historically, marriage directly concerned important questions about inheritance of land and wealth. Today, there is a growing disenfranchised population that has virtually nothing, are in debt and merely rent properties from landlords. This is exaggerated by economic stagnation. Millennials have only a fraction of the worth babyboomers had at the same age.<ref>https://archive.fo/wip/z8CaW</ref> As a result, questions of heritage and responsibility lose their
* '''Environmentalism & pessimism''': Historically, it was rarely ever a question to not have children. Usually, children were needed to maintain land, power and wealthy of the family. Associating something bad with reproduction is highly evolutionary novel.
* '''Late marriage''': The age of marriage is very late in many Western countries because of [[feminism]] and economic stagnation.