Sperm counts are way down by some measures by roughly half over the last 50 years, and people hypothesize dating apps may be responsible for the paradox that as mating became more efficient through technology, sex became less appealing.

The cross-sectional relationship between fertility and women's education in the United States has recently become U-shaped: more highly educated women are now starting to have more children compared to the recent past when there was a monotonic inverse relationship.

Bethany was shocked by Ferguson's comment about abortion futures because abortion and fertility should not be conflated or discussed in the same sentence, as they are separate topics—abortion concerns women's rights or fetal rights, not fertility decline.

Bethany did not think about mathematics or economic calculations when choosing to have her children, and had them relatively late in life, but was able to have both children and a career because of her income level and educational status.

Environmental factors like pesticides and other chemical pollutants may have dramatic impacts on human fertility and are not adequately appreciated; reduced population would allow elimination of such toxins, but the alternative (massive population using agricultural intensification) requires ubiquitous pesticide use.

Humans are sometimes rational and economic, sometimes not; people are very self-serving and their economics and rationality are directed at their own short-term well-being rather than at long-term human survival, suggesting short-termism more than irrationality drives demographic decline.

Women's rights and labor-force participation (which are unambiguously good things) may come at a long-term cost in the form of human extinction, creating a moral paradox: something that is right in one time-frame (women's freedom) may be wrong in another (species survival).

The total fertility rate in the United States is 1.64 children per woman, and if this rate persists, in approximately three generations (roughly 100 years) there will be only half as many young Americans as today.

A third of the decline in US fertility since 2007 was due to declining unintended births, and there has been a striking phenomenon of declining sexual activity among 18-24 year old men, with approximately one-third reporting no sexual activity in the past year.

Perhaps wealthy women who choose not to work do have more children but the pattern is not visible in aggregate data because it is concentrated in specific geographic and social regions, not broadly distributed across wealthy populations.

The total fertility rate (TFR) in the United States is 1.64, and if it remains at this level, in three generations (roughly 100 years) there will only be half as many young Americans as today

Having children was always implicitly an economic decision in the past because people needed children to work, but the difference in the current generation is that economic thinking about reproduction is now explicit rather than implicit

About a third of the decline in U.S. fertility since 2007 was due to the decline in unintended births, and there is a striking phenomenon of declining sexual activity among 18-24 year old men, with a third having no sexual activity in the past year

Dating apps may be an 'alien conspiracy' to cause population collapse because they correlate with a steep decline in sexual activity, making mating more efficient yet sex less appealing

People are not making fertility decisions because of debt burdens they've accumulated; if people cared about debt burdens, they would vote against fiscal recklessness, but they vote for it

Bethany disputes that pregnancy costs are the primary driver of low fertility, noting that wealthy women without careers outside the home also have low fertility, suggesting career-motherhood tradeoff is not the only mechanism

Bethany was shocked by Ferguson's conservative stance on abortion, specifically that abortion and fertility should not be in the same sentence given the importance of women's rights and the rights of the unborn

Interpreting Ferguson's comment as economist-like observation that insufficient widgets (children) means future regret is more generous than interpreting it as a political comment on whether women should be allowed to have abortions

The prospect of generational civil war as fewer young people must support an aging workforce is a frightening possibility the world has never reckoned with before, and none of our systems are built to handle it

Sperm counts have declined by approximately 50% over the last 50 years by some measures, contributing to falling fertility.