February 05, 2012
Sex Hormones Govern Genes That Control Behavior

At least in mice (and probably some day in humans) it is possible to separately tweak the expression of individual genes that are influenced by testosterone and estrogen.

Now a team of scientists at the University of California, San Francisco (UCSF) has uncovered many genes influenced by the male and female sex hormones testosterone and estrogen that, in turn, govern several specific types of male and female behaviors in mice.

Imagine being able to create humans who have very rare combinations of both female and male traits. That'll be possible eventually. Some prospective parents will opt to do it for a variety of reasons.

While testosterone and estrogen act to turn on and off groups of genes these scientists turned off individual genes from these groups to see what affect each gene's suppression caused.

The UCSF team selectively turned many of these genes off one by one and found they could manipulate individual behaviors in the mice, like their sex drive, desire to pick fights, or willingness to spend extra time caring for their young.

"It's as if you can deconstruct a social behavior into genetic components," said Nirao Shah, MD, PhD, an associate professor in the Department of Anatomy at UCSF who led the research, which is published in the 2/3/12 issue of the journal Cell. "Each gene regulates a few components of a behavior without affecting other aspects of male and female behavior.

Obviously this sort of experiment would be hard to do in humans for both ethical and practical reasons. While the ethical objections are obvious enough the practical obstacles are also quite high. Just carrying out an experiment by turning off individual genes at conception would require many experimental subjects as well as many years of waiting to see how each tweak changes cognitive processes and behavior.

But with humans lots of experiments happen naturally due to genetic mutations during fetal development or before. It is possible that with really cheap DNA sequencing scientists may be able to identify humans who already have mutations that turn off or at least turn down the expression of some of the genes that the UCSF researchers are studying in lab mice.

Share |      Randall Parker, 2012 February 05 11:29 PM  Brain Sex Differences

chris said at February 6, 2012 5:17 AM:

I can already hear the shrieking of millions of feminists in horror and anguish, like banshees on the wind.

Engineer-Poet said at February 7, 2012 11:39 AM:

Cut the spamming already, Faruq.

This is really interesting.  Sex hormones influence things like coöperation, but the gene promotors determine how gene activity is influenced by the hormones.  It may be that some of these combinations (promotors and hormone levels) work well with some forms of social organization and poorly with others.

I can also see some idealists taking this information and using it to try to create an optimal human for a heretofore-unrealizable form of society.  The potential exists for spectacular failures on the scale of Mao's Great Leap Forward.

PacRim Jim said at February 7, 2012 9:52 PM:

Will reducing all human behavior to molecular interactions really improve your life?
Extend it, possibly.
But improve it?
Why this irrational fear of death, which, after all, is only the loss of everyone and everything one knows?

That Guy said at February 8, 2012 3:13 AM:

How about blocking the sensitivity of hair follicles to sex hormones? Since follicles are conveniently located, this seems like a feasible goal for a somatic therapy. I think that topical cream that prevented the growth of facial / underarm / pubic / back hair long term would be pretty popular. RNA interference could block the downstream target for a while, or zinc-finger nucleases could do the same job permanently. Problems of systemic delivery and off-target effects can be avoided.

As an aside, whenever somebody starts talking about the "irrational fear of death" I'm left at a loss. What is irrational about it? If you enjoy the experiences that life brings, your memories, your self and your accumulated knowledge, why would you want them to cease? That seems like a perfectly rational reason to "fear" death at least in the same way that other undesirable outcomes are "feared." It's worth noting that the rationality of a belief or attitude has to do only with self-consistency as logic alone does not provide any motivations or imperatives.

joshaurora said at February 14, 2012 11:33 AM:

You mean that men and women are physiologically different and that their physiology affects their behavior. Surely these people will be burned at the stake for heresy.

Dat_Truth_Hurts said at February 15, 2012 8:12 AM:

Reducing the effects of testosterone on the population will allow strong central governments to control populations easier.

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