Thread by @lymanstoneky

So, it helps to look at the long run trend. Thread below.

https://twitter.com/drantbradley/status/1460280008413429765

Here's the long run trend in STIs I could find data for offhand. You can see there's a LOT of variation over time.

You might suppose STIs are a kind of nice objective measure of sex.

But is it really?

The obvious note here is that STIs don't arise randomly w/r/t sexual behaviors. They spread most in periods where a larger share of the population is having sex with more partners.

But multi-partner sexuality is not necessarily the biggest driver of sexual frequency! Monogamous people actually have more frequent sex than uncoupled people, so rises in average number of partners *could* actually be correlated with *less* sex overall!

Like if you suppose coupled-status causally influences sexual frequency (up) and number of partners (down), then increases in number of partners could sometimes be correlated with lower sexual frequency, especially if coupled-status is declining!

Right now, coupled status is indeed declining: marriage is getting more delayed, and the few surveys that ask about dating or cohabiting relationships seem to be showing less of those too.

So if people have less access to monogamous, low-transmission-risk, coupled sex, they may substitute to non-monogamous, high-transmission-risk uncoupled sex, which also tends to be less frequent.

As a result, you'd get 1) lower sexual frequency, 2) higher number of sexual partners, 3) higher transmission of STIs.

Finally, a note that while we have seen case rates rise across all age groups, and the absolute increase is highest among young people, the relative rate of increase has been fastest among those 55 and older.

The biggest increase is right where we'd expect: people below the median age of first marriage. That's where you'd expect a big boom if it's a change-in-coupling issue.

But the increase among older people is in relative terms quite a big faster.

I'm not 100% sure what's driving that, but the extent to which horny-retirement-community has become a meme in society kinda points to a host of potential social dynamics that could be altering later-in-life coupling behaviors.