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. Two years ago, a study of HIV transmission in Africa was called off early by the NIH, because such stark evidence of circumcision's benefits was emerging that it no longer seemed ethical to keep going. But a large meta-review of 15 other studies -- led by Gregorio Millett and published in the Journal of the American Medical Association this week -- has determined that there is no such protective effect for men who have sex with men. Circumcision reduced any given gay or bisexual man's chance of being infected with HIV by only 14%, a figure that is well inside the margin of error. Studying circumcision is tricky -- double-blind studies are impossible, for obvious reasons -- and this is by no means a conclusive finding, but it will be a useful point of departure for other research on whether it's worthwhile for men to make the cut.
Just a few days ago, it seemed like testicles weren't useful for much besides fathering children and frying up into creamy, parsley-studded fritters. But this week scientists from Germany and the U.S. announced that they've managed to extract stem cells from testicular tissue. The researchers discovered a chemical process that can turn spermatogonial progenitor stem cells (the ones responsible for churning out billions of sperm over a man's lifetime) into plain old stem cells (you know, the magical ones that can turn into basically any human tissue). They ended up making SPCs (which were taken from men during biopsies and medical castrations) into gut tissue, cartilage, bone, and skin. If this technology proves fruitful, not only would testicular stem cells be significantly easier to generate than their embryonic brethren, but they'd neatly sidestep the ethical dilemmas that have hamstrung stem cell research over the past few years.
It's well documented that women earn less than men, even when they're doing supposedly equal work. It's less obvious whether biology, socialization, or some confluence of other factors causes this discrepancy. Economists Kristen Schilt and Matthew Wiswall thought up a clever tactic to control for personhood (i.e. "human capital") while changing their subjects' gender: they looked at the labor market outcomes of transsexuals. Schilt and Wiswall discovered that women who become men earn an average of 1.5% more than they had before their gender change; men who become women earn 32% less. Their paper also points out that male-to-female transgendered workers wait an average of ten years longer than their female-to-male counterparts to transition, perhaps because of the perceived economic advantage of being outwardly male in the workplace: "Becoming a woman often brings a loss of authority, harassment, and termination," they note, while "becoming a man often brings an increase in respect and authority."
The incredible innovations, like drone swarms and perpetual flight, bringing aviation into the world of tomorrow. Plus: today's greatest sci-fi writers predict the future, the science behind the summer's biggest blockbusters, a Doctor Who-themed DIY 'bot, the organs you can do without, and much more.