The whole article was dope so I’m going to reproduce it here.  I’ll have a PDF of the original white paper in question shortly—next round of BIPT updates will be the “Hump Jones Memorial Wing”—all the great sex research I’ve been doing for the past few months. Anyways. Original link is:
http://scienceblogs.com/neurophilosophy/2007/07/alpha_male_pheromones_stimulate_neurogenesis_in_the_female_brain.php

Alpha male pheromones stimulate neurogenesis in the female brain

Category: Animal Behaviour • Neuroscience
Posted on: July 31, 2007 7:30 PM, by Mo

Females have a natural preference for mating with dominant males, because this confers a genetic advantage upon the offspring produced. When selecting a mate, animals rely on chemical cues called pheromones, which relay information about the social status and genetic health of a potential mate.

Reproductive success therefore depends upon the encoding and recall of olfactory memories; the neural circuitry in which these memories are formed consists of the olfactory bulb and the dentate gyrus of the hippocampus. But although both these sites are principle regions for neurogenesis (formation of new nerve cells), few researchers have investigated their role in pheromone-dependent mating behaviour.

The new findings show that the cells generated in response to alpha male pheromones are involved in encoding memories of the pheromone signatures that are essential for the selection of an appropriate mate.

Mak, et al exposed adult female mice to various odours by soiling the bedding in their cages with coconut, almond or male urine (which contains pheromones), and renewed the bedding every two days for either 2 or 7 days.

To determine the extent of cell proliferation in the olfactory bulb and dentate gyrus, the mice were injected with bromodeoyxuridine (BrdU, a chemical that is integrated into newly-synthesized DNA); their brains were then dissected and stained with an anti-BrdU antibody. The tissues were also stained with a molecular marker for immature neurons.

There was no significant increase in neurogenesis in females exposed to the coconut or almond odours, or in those exposed to the urine of a dominant male for 2 days. Nor was there an increase in animals exposed to the urine of castrated males, which lack testosterone and therefore do not secrete pheromones in their urine.

But in those animals exposed to the urine for 7 days, there were significantly more cells labelled with BrdU in both the dentate gyrus of the hippocampus and the subventricular zone (SVZ, the proliferative lining of the lateral ventricles were new cells are formed before migrating through the rostral migratory stream to the olfactory bulb).

Those females exposed to the urine for 7 days showed a strong preference for dominant males over subordinate ones. On the other hand, those exposed to the coconut or almond odours, or to male urine for just 2 days, showed no such preference.

These findings suggest that the pheromones in the urine of dominant males are stimulating neurogenesis, and the cells generated in response to the pheromones are involved in encoding the scent of the dominant male. If this is the case, then the newly-generated cells must be essential for mate selection in the female.

To test this, the researchers used a chemical called cytosine arabinoside to inhibit neurogenesis in females that had been exposed to urine for 7 days. These mice subsequently showed no preference for dominant over subordinate males.

Then, the researchers destroyed the olfactory system of females using an intranasal injection of zinc sulphate before exposing them to urine from a dominant male. This compound abolishes the response of females to male urine and decreases their sniffing behaviour; and, as expected, they no longer had a preference for dominant over subordinate males.

The researchers also found that pheromone-stimulated neurogenesis is mediated by hormones. Prolactin was found to stimulate the formation of new cells in the SVZ/ olfactory bulb, while luteinizing hormone stimulated neurogenesis in the dentate gyrus.

This was confirmed by the observation that exposure to urine from a dominant male did not stimulate neurogenesis in the olfactory bulb of females lacking the gene encoding the prolactin receptor, or in the dentate gyrus of females lacking the gene gene encoding the luteinizing hormone receptor.

So this study provides a model whereby male rodent pheromones stimulate the generation of new cells in the female brain; the cells generated in response to the pheromones are essential in encoding the odours of the dominant male.

According to this model, the male pheromones activate receptors in the olfactory epithelium of the female, which signal the hypothalamus to release prolactin and luteinizing hormone. These hormones then stimulate neurogenesis in the olfactory bulb and dentate gyrus, respectively, and the newly-formed cells determine the female’s preference for mating with a dominant male.

Male urine contains a mixture of pheromones, and it is not yet clear exactly which chemical - or chemicals - stimulated neurogenesis in these experiments. Nevertheless, the findings establish a possible role for newly-formed cells in the adult mammalian brain.

Researchers discovered putative human pheromone receptors last year, so naturally, these findings make one wonder about the role of pheromones in human mating behaviour. They will, of course, be of great interest to those working in the perfume industry, which is worth more than $10 billion per year.

Actually, the site this is from appears to be packed the fuck full of good brainfood:

http://scienceblogs.com/neurophilosophy/

Here’s a curious and quite possibly connected story:

http://www.newscientist.com/article/dn12411-organ-removal-gives-female-mice-a-masculine-thrust.html

Simple surgery can turn a sexually passive female mouse into a rampant sex beast. The removal of an odour-sensing organ causes female mice to pursue and mount mice of either sex, and also show masculine mating behaviours such as pelvic thrusts.

Other labs need to replicate the experiment to confirm the results, and its implications for people are unclear, experts caution. But it suggests that the rodents do have an innate sexual preference, and they have a larger capacity for gender bending than previously thought.

Unlike humans, mice exhibit a relatively narrow range of sex-specific behaviours. Previous studies have described how male mice actively pursue and mount mates, while females “just sit there and let things happen,” says Catherine Dulac at Harvard University in Cambridge, Massachusetts, US.

Experiments in recent years have highlighted the role of a tiny pocket of cells between the nose and mouth known as the vomeronasal organ (VNO) in animals such as mice.

The receptor cells in the VNO detect social-signalling molecules called pheromones, and relay information to an odour-processing region in the brain. One particular protein, TRPC2, sits in the membrane of these receptor cells and helps them fire signals. Without this protein, the VNO fails to function.

Sexually aggressive

In 2002, Dulac and her colleagues described how male mice genetically engineered to lack TRPC2 mate indiscriminately with the male and female cage-mates. Moreover, these mice did not put up a fight when other males intruded on their space (Science, vol 295, p 1493).

In the latest study, females engineered to lack TRPC2 also became more sexually aggressive, mounted mice of either sex, and made ultrasonic mating calls typically used by males.

But exactly how the lack of TRPC2 caused masculine mating behaviour in the females remained a mystery. Dulac wondered whether the lack of a functioning VNO produced this behavioural change because it had limited the development of female-specific brain areas.

To test this out, her team surgically removed the VNOs of normal adult female mice and observed the animals. Surprisingly, after the operation, the females behaved just like their counterparts that lacked TRPC2.
Human VNO mystery

Dulac interprets this result to mean that the female mouse brain is not necessarily hard-wired differently from that of male mice, at least when it comes to mating behaviours. “It really contradicts a lot of the central dogma about sex specific behaviour,” she says.

“It does shake up this field up a little bit,” says neurobiologist Nirao Shah at the University of California, San Francisco, US. “When you don’t have a functioning VNO you basically can’t tell male from female,” he says. Shah thinks that the VNO exerts a strong influence on brain circuitry, transmitting specific signals to the brain in response to pheromones.

However, other experts question why researchers have not previously observed male-specific mating patterns in previous studies that involved removing the VNO of female mice. They say that, for this reason, the results need to be further replicated for confirmation.

Moreover, scientists say that the meaning of the finding for humans is unclear, partly due to the fact that a debate exists as to whether we even have a VNO.

“Humans do not even have a functioning TRPC2 gene”, points out Charles Wysocki, a VNO expert at the Monell Chemical Senses Center in Philadelphia, Pennsylvania, US.

Journal reference: Nature (DOI: 10.1038/nature06089).

At the risk of being seen as an other kind of shit dispenser, I offer this question:

Is this why so many people women (lesbians especially.. for some odd reason) want to fuck me?

Oh wait..

Moreover, scientists say that the meaning of the finding for humans is unclear, partly due to the fact that a debate exists as to whether we even have a VNO.

I suppose it does not really apply.

Hmm

Bit more seriously, what effects determine “dominant” males?
I mean.. some guys have ADD (talk a ton; draw attention).. some others just body-build a lot and walk around shirtless.  Some are thoughtful-manipulative, others are physical-manipulative.  There are many more factors.. but what is dominant?  Angry people?  Loving people?
*grumble*