Why so much teenage sex?

Jeremy Greenwood in recent years has had a knack for analyzing societal topics under an economic angle. His latest, with Nezih Guner, is to try and understand why premarital sex has increased so much in a century. While presumably the enjoyment of sex has not changed, the cost of it has significantly decreased, they argue: contraception is more readily available and less expensive, error correction devices like abortions and recently say-after pills are less dangerous.

They also argue that the young are now better educated about sex, and make this part of a reduction in the cost of sex. I am not sure I quite follow this. Sex education is an information, not a cost issue. And it can cut both ways. One may now be better educated about contraception, which would raise the likelihood of premarital sex, but one also knows better about the consequences, and this should reduce this likelihood. We all have gone through this, and one tends to do stupid things in those years. In fact, one could argue that some form of hyperbolic discounting would be better indicated, at least until the twenties.

In any case, I still think that the argument about reduced cost Greenwood and Guner is a good one. I fail to see, however, why this needed 62 pages to be fleshed out. Any simple dynamic model would have been sufficient, no need for a complex matching model. And while their history of condoms starts with Casanova, they fail to mention that ancient Romans already used goat bladders for that purpose, and others later goat and sheep intestines.