Julia Wallace

It has long been known that contracting HIV through oral sex is rare. Klara Hasselrot of Stockholm's Karolinska Institutet recently wrapped up a study--detailed in a forthcoming paper in the international AIDS journal AIDS--that might shed some light on why this is. It provides the first-ever evidence that humans can develop resistance to HIV in their saliva.

Good news, crackheads! You can now smoke, snort, or freebase with impunity while pregnant, and your baby will probably only turn out a little weirder than it would anyway.

It's the ultimate geek fantasy: a metal-and-plastic woman of your own, brought alive by technology (the geek's own stock-in-trade), who somehow becomes hopelessly devoted to you. In both science and science fiction, the creation of female robots has tended to revolve around a housekeeper-whore dichotomy: the fembot is either a docile domestic helper, or a sexually uncontrolled, well, sex machine. Historically, she has simultaneously embodied men’s deep desire for idealized domestic companionship and their fears of being destroyed by unbridled female sexuality.

I once read in Cosmo that men get sleepier post-orgasm than women do. Is this a bunch of bull? It's not like men crash after masturbating. Could it be attributed to physical exertion, rather than some hormonal response?
- name withheld,
Massachusetts

This is actually a well-documented phenomenon, complete with hundreds of Yahoo! Answers queries (my favorite response: "well probly idk mayb there jus bored lol") and a book called, yup, Why Do Men Fall Asleep After Sex? Even Arianna Huffington has weighed in ("Men go to sleep because women don't turn into a pizza," Men's Health editor Dave Zinczenko informed her.)

There's no hard-and-fast consensus yet, and physical exertion probably plays a small-to-middling role in the post-sex snoozathon, but the chief culprit seems to be

It sounds like just another uber-meltable cheese product, but Vavelta is actually miles away from anything you'd want to put in your mouth. It's a radical new treatment for facial pitting, scarring, and wrinkles made out of—what else?—newborns' foreskins. Foreskins have long been treasured by cosmetic dermatologists because they are rich in fibroblasts, tiny cells that play a crucial role in healing wounds and generating collagen and connective tissue.

A few weeks ago, Hanna Rosin's wrenching and well-researched article about young transsexuals—including a girl named Bridget (née Brandon), whose first words were "I like your high heels"—zipped around the blogosphere. In it, Rosin discusses the unsettling work of a psychiatrist who questions the scientific basis for allowing children to "transition" to the gender of their choice, citing several kids who emerged from their gender dysphoria after a rigorous course of therapy. "If a 5-year-old black kid came into the clinic and said he wanted to be white, would we endorse that?" he asks. The prospect of letting pre-pubescent pipsqueaks take hormone-blockers that might have far-reaching effects on their health and future fertility is indeed a little nerve-wracking.

But just on the heels of Rosin's piece, researchers based at Australia's Prince Henry's Institute this month released the results of the largest ever study of transsexual genetics, which compared the length of the androgen receptor (AR) gene in 112 male-to-female transsexuals and a control group of 250 "normal" men.

Holy crap. These guys in Germany just cured AIDS!

Of course, the procedure is so expensive, complicated, and risky that it's not replicable as a large-scale public health strategy, but we'll ignore that for a minute. Here's how they did it.

Nikon’s annual Small World Competition has been awarding prizes to the country’s best microscope-aided photography since 1977. The contest winners always present a reliably fascinating and freakish slice of life at a Lilliputian level. Last week, this year’s 115 winners were announced.

The cute and cuddly prairie vole, one of only a few mammals that remain monogamous for most of their lives, has long been a favorite “lab rat” for scientists studying love and attachment. Now researchers at Emory University and the University of Regensburg have found that prairie voles actually show signs of grieving—the opposite of attachment—when they’re taken away from their romantic partners.

It's been a hot week in the science of sex.

First of all, for all of you Intactivists out there (and I know there are a lot of you round these parts), a major finding might bolster your claim that routine circumcision isn't worth the risk.