The elephant in the room whenever you’re discussing stuff and clutter is sex.

(That’s sex as in gender, although our style guide at The Economist urges us to use gender only for words and sex for people. So the gender of ein Mädchen is neuter, whereas her sex is female.)

I believe we can stipulate that:

women need and keep and hoard, and cannot let go of, stuff much more than men do

Is this controversial? It shouldn’t be. It’s mostly women I’ve talked to who have said as much. If you go into a random house and count things, the odds are that “hers” outnumber “his” (although that need not apply to total weight or size, of course). It’s women who agonize over getting rid of things, not men.

(To pre-empt a Larry Summers situation, this is the time to remind everybody that I’m making a statement about averages and statistical dispersion. Of course, there are individual men who keep more stuff than individual women.)

So the question is: Why?

1. One possibility is our hunter-gatherer past, which accounts for almost all of our time as a species. Whereas Neanderthal men and women hunted together, our ancestors sent the men to hunt and the women to gather, and benefited from this division of labor. A hunting party travels light. The less you carry the more fiercely you will wield what you do carry, and the more likely you will be to bring your prey back, which is the point. Stuff would only interfere. By contrast, gathering is about stuff, the collecting of it.
2. Another possibility is that the nesting instinct shows up in females even outside of pregnancy, though perhaps to a lesser extent. Get a male (we’re not necessarily talking about our own species) to build a nest, then fill it up. All the way up. Don’t drop anything.
3. The previous two points might just add up to a third possibility: That women have a stuff brain but men don’t. I read research somewhere (which applies eerily in my case) that men are usually better at, for example, such tasks as rotating an imaginary object in space, whereas women are better at remembering and locating objects in a crowded drawer that is briefly opened and shut. Men can’t find anything, women seem to find everything. (When I need something, I usually ask my four-year old daughter, and she always knows.)