Picking items for "Human Nature" is always a bit embarrassing. Should we go with the latest deep challenge to life as we know it, or the sick wire story we can't stop gawking at? The baby whose smiling, blinking second head had to be severed? The woman who gave birth to her own grandchild? The museum exhibit on gay animals? The driver who used her fetus to qualify for a carpool lane? Fish that grow meatier when you change their sex?Pro athletes who freeze their babies' stem cells to cure their own injuries? Parents who substitute bedroom TV for intercourse?
Memorable stories all, but none of them made the year's top 10. Here are the winners. (For related news and columns, you can click through to each item's original page.)
1. Scientists have grown and implanted the first custom-made human organs. They made bladders and put them in patients who donated the source tissue. Recipe: Take a tiny tissue sample from each patient, grow it in a dish, wrap it around a scaffold to shape it, grow it for seven weeks in an incubator, then put it in the patient, where the new bladder keeps growing. The bladders have been functioning in seven patients for about four years. Next, scientists plan to grow kidneys, livers, and hearts. Interpretations: 1) Tissue engineering has arrived. 2) We did it without embryonic stem cells. 3) Death, RIP.
2. In 10 years, self-reported oral sex has more than doubled among people aged 12 to 25, according to a comparison of 1994 and 2004 data in Baltimore clinics that manage sexually transmitted diseases. In a sample of more than 6,000 young people, the percentage of males reporting oral sex in the preceding 90 days rose from 16 to 32; the percentage of females reporting oral sex rose from 14 to 38. Meanwhile, the percentage of females reporting anal sex rose from 3 to 5.5. Interpretations: 1) More teens and young adults are having oral sex because they think it's safer than vaginal sex. 2) That's true of some infections but not others. 3) This is foiling urine tests, which are supposed to diagnose STDs but don't catch oral or rectal infections. 4) We'll have to warn kids more explicitly about the risks of various activities.
3. Several U.S. fertility clinics admit they've helped couples deliberately select defective embryos. According to a new survey report, "Some prospective parents have sought [preimplantation genetic diagnosis] to select an embryo for the presence of a particular disease or disability, such as deafness, in order that the child would share that characteristic with the parents. Three percent of IVF-PGD clinics report having provided PGD to couples who seek to use PGD in this manner." Since 1) the United States has more than 400 fertility clinics, 2) more than two-thirds that answered the survey offer PGD, and 3) some clinics that have done it may not have admitted it, the best guess is that at least eight U.S. clinics have done it. Old fear: designer babies. New fear: deformer babies.
4. Lesbian brains differ from straight women's brains. Last year, a study showed that gay men, like straight women and unlike straight men, processed a male pheromone in a sex-related part of the brain (the hypothalamus) but processed a female pheromone in a scent-related part of the brain. Now the authors of that study report differences among women: 1) Lesbians, like straight men, prefer the female pheromone and find it less irritating than the male pheromone. 2) Straight women find the female pheromone more irritating. 3) Straight men and women process same-sex pheromones in the scent area but process opposite-sex pheromones in the hypothalamus. 4) Lesbians process pheromones of both sexes in the scent area. Interpretations: 1) Sexual orientation is biologically based, not a choice. 2) Sexual orientation is more biologically based in men than in women.
5. A longitudinal study suggests whiny kids grow up to be conservative.They "turned into rigid young adults who hewed closely to traditional gender roles and were uncomfortable with ambiguity. The confident kids turned out liberal and were still hanging loose, turning into bright, non-conforming adults with wide interests." The authors suspect "insecure kids look for the reassurance provided by tradition and authority," whereas "the more confident kids are eager to explore alternatives." This matches a 2003 analysis that suggested "people who are dogmatic, fearful, [and] intolerant of ambiguity ... are more likely to gravitate to conservatism." Criticisms: 1) They did the study in Berkeley. 2) The correlations aren't that strong. 3) They skewed the interpretation, calling moral confidence "rigidity." 4) They overlooked left-wing rigidity. 5) What about the recent Pew study that showed Republicans are happier than Democrats?
6. Chinese doctors performed the world's first documented penis transplant. An unexplained accident left the patient with a "small stump," unable to urinate properly or have sex. Doctors gave him the penis of a brain-dead man whose parents agreed to donate it. Good news: After 10 days, he could "urinate smoothly" and showed no signs of tissue rejection. Bad news: After two weeks, "because of the wife's psychological rejection as well as the swollen shape of the transplanted penis," the organ "regretfully had to be cut off." Upbeat conclusion: We're figuring out the human body. Skeptical conclusion: We still have no clue about the human mind.
7. The military is funding research into remote control of animals. Using brain implants, scientists have trained rats to navigate rubble and detect explosives. Now they're manipulating monkeys, fish, and sharks. Method: From your laptop, you send a radio signal to an antenna implanted in the animal. Different signals stimulate different parts of the brain, directing the animal's movement. Meanwhile, you try to read from the animal's brain what it's seeing, smelling, or hearing. Goals: 1) Learn how animals operate. 2) Learn how to help disabled people control their movements. 3) Turn sharks into remote-controlled naval spies, since they're self-powering and quieter than underwater vehicles.
8. Scientists chopped off part of a chick embryo's wing and grew it back. They did it by boosting production of proteins that spur limb growth. Frogs and salamanders can regrow limbs, but until now, we thought chickens couldn't. Theory: Evolution has turned off the ability to regrow limbs in many species, but the ability's still there, if we can figure out how to tweak the genes. Happy spin: By tweaking cells from your arm stump, we can turn them into stem cells and regrow your arm. Horror spin: There's a reason why evolution turned off these genes: Cells from some chicks in the experiment became cancerous, and other chicks "sprouted several appendages."
9. A German institute is developing spray-on condoms. Rationale: Unlike regular condoms, which may not fit you, a spray-on is a custom job. The technology consists of a "spray can into which the man inserts his penis." It "works by spraying on latex from nozzles on all sides … once round and from top to bottom. It's a bit like a car wash." Idealistic prediction: The spray can will prevent pregnancy and disease by sheathing men. Cynical prediction: It will prevent pregnancy and disease by replacing women.
10. Tall people are smarter than short people, according to an analysis of two studies. Data show that tall people make more money than short people. Previous explanations: 1) Our bias for taller people makes us pay them more. 2) Our bias for taller kids gives them more self-esteem, which helps them succeed. 3) Taller kids are healthier, which helps them succeed. New explanation: Kids who will grow up to be tall are smarter than kids who will grow up to be short. Key evidence: "As early as age 3—before schooling has had a chance to play a role—and throughout childhood, taller children perform significantly better on cognitive tests." Approving reaction: another blow against egalitarian correctness. Skeptical reaction: This is just the kind of Ayn Rand garbage you'd expect from two Princeton economists who are 4 inches above average height.