WEIRD isn't really an insult here — it's an acronym. Western, Educated, Industrialized, Rich, Democratic. And it describes something like 12% of the people alive today.

Here's the part that's genuinely strange: roughly 96% of the people psychologists study when they claim to be studying "human behavior" come from that same 12% (Henrich, Heine, & Norenzayan, 2010). The population used to define what counts as a normal human mind is, numerically, one of the least typical groups of humans on the planet.

Jonathan Haidt uses the same acronym in The Righteous Mind to make a related point about morality (Haidt, 2012) — it's one of those ideas that keeps resurfacing once you know the term exists.

Take fatherhood, since that's the thread running through this project. A lot of what gets called "the biology of fatherhood" — hormone shifts, brain changes — comes from exactly that narrow slice: university-adjacent samples in the U.S. and Europe, mostly. A 2021 review of every fMRI study ever done on fathers' brains found the samples came from six countries — Israel, the Netherlands, the U.S., Italy, Germany, Finland — and several of those studies came out of the same handful of labs (Provenzi et al., 2021).

Here's an example that stuck with me. Hadza men in Tanzania — hunter-gatherers — show a drop in testosterone after becoming fathers. Their neighbors, the Datoga, who live close enough to share the same land and climate but herd cattle instead of foraging, show no drop at all (Muller, Marlowe, Bugumba, & Ellison, 2009). Same region. Opposite pattern. It's a small study, and not one tracked over years, so I'm not calling it proof of anything — but it's a real data point that has nothing to do with WEIRD countries at all.

Then, almost as a counterpoint, a study came out this year asking the exact same testosterone question about thousands of American men, using government health records instead of a university subject pool. The drop showed up again (Gettler & Hoegler Dennis, 2026). So the issue isn't that WEIRD data is wrong. It's that one part of the world has been asked the question constantly, and the rest of it only occasionally.

Steve Stewart-Williams talks about genes and memes — biology and culture — evolving side by side, neither one running the show. A pattern that shows up in one culture and disappears in its neighbor isn't a contradiction under that view. It's closer to the point.

I don't have a clean conclusion here, and I think that's honestly the point. I've got kids of my own, and being a father hasn't waited around for the sample sizes to catch up. Whatever this research eventually settles, showing up already mattered before anyone measured it.

It makes me wonder how much of "the research on fatherhood" is really research on fatherhood as it's lived by the twelve percent of the world that keeps getting asked — and how much of the real picture is sitting somewhere nobody's gone to look yet.