Today PLoS Biology published a study of fruitflies, a species where the male flies show a marked preference for mating with larger females because they are more fecund. The problem is that the males show such aggressive preferences that they basically badger the females constantly to mate. What this means is that the females are so harried that they have less time to search for food, which degrades their health. Also, among fruitflies, the mating process is itself damaging to the health of the females - fruitfly sperm is toxic.

As a result, the most-desired females become far less capable of generating healthy offspring. And the smaller, less fit females wind up bearing as many offspring as the fitter ones. In the end, the males' aggressive mating with the fittest females ends up preventing their species from evolving into a much fitter group.

Tristan A. F. Long, one of the authors of the study, said:

These larger females are disproportionately harassed and harmed, by males attempting to obtain matings. When these males are ‘choosy' with their courtship, there may be negative consequences to the species' ability to adaptively evolve.

What's interesting about this study is that it's one of the few to point out how male mate choice affects evolution of a species. Usually female mate choice is emphasized, except in species where females are dominant. Here we can see clearly that male mate choice is having a profound and not very salutary affect on the future of fruitfly fitness. The issue here is obviously not attractiveness, but instead the kind of fitness associated with being larger and more fecund. If larger, "attractive" females are harrassed into reproductive uselessness by the males, then any traits they possess that make them healthier (a trait for metabolic efficiency, for instance) won't be able to spread through the population as quickly as it might if males chose mates randomly.

via PLoS Biology

National Geographic photographer Martin Oeggerli took a series of gorgeous, and (oddly) recognizably sexual photographs of pollen in action. In this gallery - and many other photographs of his in the National Geographic gallery - you can see how the plant sexual cycle works. From feather-borne pollen to a piece of pollen that is growing a sperm injector, every kind of flower smut is represented.

You can see more of Oeggerli's work on his website.

via National Geographic (thanks, Marilyn Terrell!)

Geranium
Flowering quince
Forget Me Not
Indian mallow - this pollen shape is designed to stick to bird wings.
Pine
Snowball blossom - pollen has fallen into the stigma of another snowball blossom, and the pollen is swelling with water. One pollen grain is growing a tube that can inject sperm into the flower.
Willow - this piece of pollen will die, because it got trapped between two petals before pollenating anything.

A paper published in this week's Public Library of Science ONE examined the obstacles to mammalian reproduction in space. While frogs, salamanders, and sea urchins all have proven records of extraplanetary fertility, mammals sent to space have not fared so well in the breeding department.

The team of Japanese biologists decided to investigate the impact of low gravity on mammalian embryonic development. They stored mouse eggs and sperm inside a three-dimensional clinostat, a device that mimics the effects of weightlessness, and then fertilized the eggs, allowing some to develop inside the clinostat and others to develop in normal gravity.

They found that, while fertilization occurred normally in the simulated microgravity, embryos that continued to develop in the clinostat had more difficulty dividing and maturing than those developing in normal gravity. Some of the embryos did survive and were implanted in mice, but they survived in much lower numbers than the embryos that were fertilized in the clinostat but developed outside it (no word on the relative health of the mice that were ultimately born). And the experiment suggests that mammalian embryos are especially sensitive to changes in gravity, and that it might be difficult for humans to reproduce in places where the gravity does not resemble Earth's.

Making Babies in Space May Be Harder Than It Sounds [Wired]

Plant biologists at the University of Leicester researched the unusual plant reproduction system, trying to figure out how it works on the genetic level, and published their findings today in PLoS Genetics. According to David Twell, one of the co-authors of the paper:

Flowering plants, unlike animals require not one, but two sperm cells for successful fertilisation. One sperm cell to join with the egg cell to produce the embryo and the other to join with the central cell to produce the nutrient-rich endosperm tissue inside the seed. A mystery in this 'double fertilisation' process was how each single pollen grain could produce the pair of sperm cells needed for fertility and seed production.

We now report the discovery of a dual role for DUO1, a regulatory gene required for plant sperm cell production. We show that the DUO1 gene is required to promote the division of sperm precursor cells, while at the same time promoting their specialised function as sperm cells. It effectively switches on the essence of male.

So what's the upside for you? First of all, it could help plant-growers understand gene flow in their crops. On a more pure research level, this discovery might help evolutionary biologists better understand what makes flowering plants such a successful form of life; and it may even shed light on boring old single-fertilization reproduction that we animals engage in.

But I think we all know what's really going on here. This lab is trying to prevent the spread of Triffids across the Earth by messing up their reproductive systems. Thanks, Leicester plant biogeeks, for saving the world by studying plant sperm. Those of us who don't fancy being eaten by giant plants from space totally appreciate it.

via PLoS Genetics

Image generated by Lynette Brownfield (University of Leicester).

These breakthroughs are roughly in chronological order.

Non-procreative sexual behavior is common
In 1886, a psychiatrist named Richard von Krafft-Ebing revolutionized the discipline of sexology by publishing his exhaustively researched tome Psychopathia Sexualis. He'd documented every case he could find of what he called "sexual perversity," including those he'd encountered first-hand among his patients. He defined sexual perversity as pretty much anything that deviated from procreative, heterosexual sex, and put each perversion into its own special category. Though he intended to document perversity, the book had the opposite effect: Many doctors and ordinary people read it and realized that many kinds of "perversity" were so common that they were almost normal. The (relatively) unbiased reporting and taxonomic structure of Krafft-Ebing's book inspired countless other early-twentieth-century researchers, including Sigmund Freud, Magnus Hirschfeld, and Alfred Kinsey. Though published over a century ago, Psychopathia still has the power to shock.

Bisexuality exists
Sigmund Freud, the father of modern psychiatry, is famous for remarking that everyone is bisexual. His idea was remarkable for two reasons. One, it acknowledged that there was a middle position between gay and straight (a relatively rare belief among doctors); and two, it paved the way for a more nuanced understanding of how sexuality exists on a continuum rather than as a binary system. Jumping off from Freud's idea, infamous twentieth century sex researcher Alfred Kinsey created what has come to be known as the Kinsey Scale for sexual orientation. On that scale, 0 is completely heterosexual and 6 is completely homosexual. Kinsey and his colleagues did decades of in-depth research to determine that most people fall somewhere in the middle of the scale. You can see their research in Kinsey's most famous works: Sexual Behavior in the Human Male and Sexual Behavior in the Human Female. All research was based on thousands of anonymous interviews conducted all over the United States.

Medical science can transform men into women, and vice versa
Throughout recorded history, there have been women who lived as men and vice versa. Many cultures even have the idea of a "third sex," often a shamanistic role, which is for people who are neither male nor female. But it wasn't until 1930 that the first sex change operation was performed on a famous Dutch artist named Einar Wegener, who emerged as the woman Lili Elbe. Unfortunately, the operation was crude - it involved implanting ovaries - and she eventually sickened and died (you can read her intriguing memoirs about her transition). The first successful male-to-female sex change operation was performed in Denmark in 1952, and its recipient, Christine Jorgensen, became an international celebrity. Since then, thousands of people have had successful sex reassignment surgeries, moving from female to male and male to female with the assistance of medical science.

Women have orgasms
The female orgasm has been "discovered" several times over the past 130 years. In the nineteenth century, doctors used vibrators to help relieve women of "hysteria," though almost no medical accounts from the time acknowledge that this therapy was basically masturbation. The Victorian Era had given rise to the myth that women didn't have orgasms, and many medical researchers adopted this idea as truth because it was impossible to prove that women were orgasming the way you could prove men were. Though anecdotal reports and throughout the twentieth century indicated women could orgasm the way men could, it wasn't until the experiments of sexologists William Masters and Virginia Johnson in the late 1950s that the female orgasm was finally proven to exist in a scientific manner. Masters and Johnson observed women in the process of orgasming while monitoring everything from blood flow to muscle spasms in their vaginas. (Yes, they actually inserted a dildo-shaped measuring device into the women's vaginas to do their research.) After Masters and Johnson published their research in 1966, several other researchers investigated women's sexual response cycle, quickly discovering the G-spot, female ejaculation, and even looking at orgasming women in MRI machines (you can see a picture of that at the top of this post). Recent research into female orgasm has focused on the neurochemistry of women's brains while they are aroused.

Pregnancy can be prevented with a pill
In 1960, the birth control pill debuted on the market as a contraceptive for women. In the late 50s it had been prescribed to women who suffered extreme menstrual cramps. But in the early 60s the pharmaceutical known as "the Pill" became not just a sexology discovery but shorthand for a sexual revolution that had more to do with culture than science. Freed from cumbersome birth control devices like condoms that depended on male cooperation, women could suddenly have sex without the constant worry that they would become pregnant. Many historians have argued that the Pill helped start a new wave of feminist consciousness. The Pill is an excellent example of how a scientific discovery can have widespread, unintended social consequences.

Homosexuality is not a disease
In 1973, homosexuality was removed from the Diagnostic and Statistical Manual of Mental Disorders (DSM-II). That meant that after decades of debate, the professional psychiatric community would no longer treat homosexuality as a disease. Certainly an unhappy homosexual might be viewed as neurotic, but a happy, well-adjusted gay person would be given a clean bill of health. Many sexologists had been arguing for decades that homosexuality was not a disease, most notably the openly gay psychiatrist Magnus Hirshfeld, who founded the Berlin Institute for Sexology (which was later burned down by the Nazis). But the removal of homosexuality from the DSM made it official: Licensed doctors now agreed that gayness on its own was not an illness.

Many kinds of male impotence can be cured with a pill
In 1998, men got their own version of the Pill. A chemical called sildenafil citrate came to market under the name Viagra. Sildenafil works by relaxing muscle tissues, allowing more blood to flow into the penis. Just as the Pill liberated women from fears of pregnancy, Viagra liberated many men from fears of impotence. While sildenafil didn't set off a cultural revolution, it did represent a major scientific breakthrough - and has helped researchers understand male sexuality better. Viagra and similar drugs like cialis are among the bestselling "lifestyle pharmaceuticals" of all time, raking over 1.5 billion dollars per year.

Orgasms can be caused via direct neural stimulation of the spinal cord
In 1998, the same year Viagra hit the market, Dr. Stuart Meloy made a strange discovery while operating on a woman's spinal cord. He was stimulating her nerves in order to locate the source of her back pain, and when he hit one particular nerve he gave her an instant orgasm. "You should teach my husband to do that," she told him. Meloy went on to patent a spinal implant device, which he hopes to market as a cure for female sexual dysfunction (i.e., an inability to have orgasms). He's in the process of testing the device now, and is actively seeking volunteers - female and male - so that he can perfect the device and bring it to market. Once he's got a version of the device that people can use easily, you can expect a sexual revolution that will make the Pill look like a walk in the park.

Women ovulate more than once per month
In 2003, a researcher named Roger Pierson at the University of Saskatchewan overturned the almost century-old scientific belief that women ovulate once a month. He and his team used simple ultrasound scans on 63 women with normal menstrual cycles, and discovered that a significant number of them ovulated 2 or 3 times per month. Their finding could have a significant impact on how we understand female hormonal cycles and fertility.

Top image, an MRI of a woman during sexual arousal and orgasm, from British Medical Journal.

Psychopathia Sexualis image by drjoanne

Annie Sprinkle reading Alfred Kinsey via The Bohemian

Wonder of life and all that crap. But seriously — wonder of life! It's pretty awesome. Now if only I could get a robot to do this for me, instead of having to poot out those eggs myself every month, I would be totally psyched.

Human Ovulation Caught on Film [via New Scientist]

According to New Scientist:

The device is placed inside the vas deferens - the duct which carries sperm from each testicle to the penis. When closed, it blocks the flow of sperm cells, allowing them to pass again when it is opened via a remote control. The valve could be a switchable alternative to vasectomy, the researchers say . . . The silicone-polymer valve can be flipped between open and closed positions with a pulse of radio waves. A set of conducting "fingers" on the valve act as antennae and convert the signal's energy into sound waves that travel through the polymer and create stresses inside the device.

One scientist calculates the human Y chromosome will be extinct within 125,000 years if current trends continue. That's an eyeblink in evolutionary terms. Already, the Y chromosome is filled with more junk DNA than other chromosomes, because it passes from father to son without any input from the mother. Decreasing sperm counts mean that boys are more likely to receive a damaged copy.

So how can our macho little vole from Kyrgyzstan help? Because he's lost his Y chromosome already, and he somehow transferred the genetic information that confers maleness to another chromosome. So it could be possible to transfer the sex-determining region of the Y chromosome to another gene in humans as well. [London Times]

A company called Anacova has won an award for its new embryo-baking technology, a special stick full of "embryo environments" that gets stuck in a woman's womb for a week or so. Usually when embryos are fertilized for IVF, they live the first few cell divisions of their lives in an incubator. Apparently this lowers the quality of the embryos, so the Anacova device — which exposes embryos to the womb environment — is expected to produce higher-quality proto-humans for harvesting. That means you can add one more person to your outsourced womb list. There's the surrogate who gives you her egg, then the embryo-cooker who gives you her womb for a week or so while your embryo ripens, and then the surrogate who carries the baby to term. [Medgadget]

A new longitudinal study in Canada proves that divorce does not affect parenting skills. [Eurekalert]

A researcher in Chicago figured out that drugs regulating synaptic behavior can make fruit flies gay within hours. Apparently homosexual behavior in fruit flies is biological, but not hardwired. It's extremely unlikely that such a drug would work in humans, since our brains are so different and our sexualities much more complex. Still, a girl can dream, can't she? Christina Ricci, you will be mine! [Science Daily] Image of nanotech device courtesy of Cornell University.