Emily Anthes discusses how men's bodies prepare for fatherhood.

Real-time discussions with Slate writers.
June 15 2007 11:52 AM

Super Dads!

Emily Anthes talks with readers about how men's bodies prepare for fatherhood.

Science writer Emily Anthes was online at Washingtonpost.com on Thursday, June 14, to discuss the  physical and hormonal changes new dads go through. An unedited transcript of the chat follows.

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Emily Anthes: No, no pregnancies for me yet. But now I'll know all about pseudo-pregnancy if and when it ever becomes part of my life.

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New York: Why would less testosterone in fathers be adaptive? Don't babies need strong protectors (both male and female) to fight potentially harmful aggressors?

Emily Anthes: Good point. I'm sure that there is a tradeoff involved. But if the testosterone drop was naturally selected for, it means this tradeoff was worth it for dads. Levels of the sex hormone don't stay permanently low in men—they're just depressed when their children are the youngest. Perhaps, for the first few weeks of her life, a child is better served by having a father who's around than one who's out fighting. But that's just my own speculation. I'd imagine that a drop in testosterone doesn't preclude a father from defending the nest.

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Middleton, Wis.: Hi Emliy. Interesting topic. I became a dad 12 days ago and have been surprised at how my latent "motherly" instincts have appeared. I also have a twin sister—do you know of any studies on the effect that has on one's fatherhood? I have heard about studies showing (I believe) less testosterone among men with a twin sister. Thanks!

Emily Anthes: Congratulations on becoming a father. I don't know about that study specifically, but there are some studies in rodents (I believe) that show that males who were positioned between two females in the womb have different paternal behavior than males who were positioned between two males. I don't know all the details, but the hormonal environment of the womb does seem like it can make a difference.

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St. Paul, Minn.: I have four grandsons, and when they were born I told people—only half-joking—that I thought there were grandmother hormones because the attachment was so immediate and so much like what I experienced when my children were born. This conversation reminds me of that phenomenon. Is there any evidence that a woman's body remembers that maternal response and that it kicks in again with a new generation?

Emily Anthes: There is some anecdotal evidence that pregnant women's female relatives (sisters, mothers, mothers-in-law) can experience sympathetic pregnancy (sometimes complete with a belly to match).

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Blacksburg, Va.: My husband (ordinarily an endomorphic 6-foot, 145-pounder) gained 30 pounds during both of my pregnancies—and then lost all the weight faster than I did. Most irritating.

Emily Anthes: I bet. I'm sure there are other moms in the same boat. But take heart—maybe he was doing it all for the good of your children.

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Emily Anthes: Well, it looks like that's a wrap. Thank you for joining me. Happy Father's Day to all you dads out there.

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