[Pinwheeler]

Let's not forget: Correlation != Causation.

Does being in a relationship lower your testosterone?

Or are women(assuming the men in study were heterosexual, not sure on that, either) more interested in entering into LTRs with men with lower testosterone levels?

Edit: Also, was this controlled for age?

[seccess]

Or, are men with naturally lower testosterone levels more likely to stay in a single LTR?

[Pinwheeler]

ooh, also a possibility!

[FrankenPC]

This is one variation of a particular line of research. Sexual orientation vs testosterone would be another good one. Getting periodic testosterone readings before long term relationships and then after would be even better to develop a trend. Locating an actual mechanism that modulates testosterone based on instinct/emotions would be even better.

[mindcruzer]

My guess is that it's the former. In general, women are attracted to masculinity (assuming heterosexuality), a factor in which testosterone plays a large part.

[patal]

Let them be attracted. Serves reproduction all right. Hence your evolutionary argument. But the study is about long-term relationships. I'd think social factors, cultural habits, and reflection play an important part there. It's not clear to me, that it's necessarily the former.