William Saletan contends that this study on fathers having lower testosterone is being oversold:
Testosterone affects and is affected by many things. It probably does adjust to environmental cues as men become mates and then fathers. But we're just beginning to explore how and why this happens. The new evolutionary-psychology theory we're being fed has less to do with earth-shattering evidence than with changes in our economy and culture. Women are gaining more respect and consideration. Wages have shrunk, so both parents have to work for pay. Men have to help out more at home, and they can't get away with cheating the way they used to. For a bunch of reasons, we need a more domestic and egalitarian theory of masculinity. And we're using this study to sell it.
Christopher Ryan rebuts another piece of spin, "that this effect is about being a biological father."
The Dish 