

Fatherhood depletes testosterone, study finds - tokenadult
http://www.latimes.com/news/science/la-he-fathers-testosterone-20110910,0,241588.story

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lukesandberg
I read a great book about things like this: [http://www.amazon.com/Why-We-Get-
Sick-Darwinian/dp/067974674...](http://www.amazon.com/Why-We-Get-Sick-
Darwinian/dp/0679746749)

There are several chapters about the hormonal effects of childbearing and what
the evolutionary benefits are for the children. A few i can remember off the
top of my head are:

Breastfeeding will often prevent women from ovulating and thus becoming
pregnant. In this way mothers resources are not strained by taking care of too
many children at a time and the current child will have a better chance of
survival.

Fetuses secrete a hormone called human placental lactogen that inhibits
maternal insulin, this leads to high glucose levels in the blood and thus more
nutrients available to the fetus it can also result in diabetes in the mother
during the pregnancy.

preeclampsia (gestational high blood pressure) is another similar effect where
hormones excreted by the fetus raise maternal blood pressure in order to
increase blood flow to the placenta.

Having a fathers testosterone levels fall during early parenting is probably a
key evolutionary adaptation because it would prevent fathers from seeking new
mates (in order to make more babies and thus spread their genes) in order to
care for the new child. The study noted that testosterone levels later rose
when the children became older, this too follows the evolutionary argument
because once a child is old enough it is more efficient for the father to
attempt to father more children.

By far the most interesting part of this section in the book was about male
jealousy. The theory is that because it is fairly difficult for a man to tell
whether or not he is raising another mans child. men have evolved to be overly
protective of their chosen mates so that they do not invest to many resources
(time included) and thus lower their own genetic viability. Jealousy, while
present in both sexes is a much stronger emotion in men (according to the
authors this is true across all cultures).

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Groxx
How does one quantify jealousy? It seems such a measurement must be
subjective, and highly-influenced by both your definition and by your
environment.

edit: especially when there's an equally-rationalizable reason for women to
have jealousy: to keep the man around as provider / protector while they're
more incapacitated than usual. They're stuck either risking their child with
another man (not an evolutionarily sound action), or preventing him from being
tempted away by more fertile prospects.

~~~
lukesandberg
The way the authors quantified it was by taking cross cultural surveys.
Basically they surveyed men and women from various cultures about their
attitudes around jealousy and determined that in all cultures they studied men
appeared to be more affected by jealousy.

You are right that there is a rational reason why women should be jealous as
well. But women have a more rational reason to forgive their mate, because it
is far easier for a man to walk away from the relationship and thus the child.

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rileyjm
I would like to know if the reverse effect can be produced on women. Can women
produce more testosterone in situations that would generally be considered
more masculine? There seemed to be a very significant finding for men who just
had newborns, perhaps it is triggered more by a major life event rather than
specifically becoming a parent. For instance, does getting married reduce
testosterone? Does losing a love one reduce it? Does moving to a new home?
Makes for an interesting article and find(?) but I don't think it can be
significant until it can be concluded that parenting specifically reduces that
hormone.

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reinhardt
I had to do a double take this wasn't an Onion article. How on earth can the
body "know" whether one has become a father? Turns out the term "fatherhood"
is misleading or at least ambiguous. As the Hadza vs the Datoga example shows,
it's not the act of inseminating a female that causes testosterone depletion
but the lifestyle changes often (but not always) associated with fatherhood.

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cheald
You know, I can pretty safely say that fatherhood depletes _everything_.

