Image: Wikimedia Commons
Proceedings of the National Academy of Sciences, November 17
When is a goat like a reptile? When it’s cold-blooded, slow-moving, and fond of sitting on warm rocks. Researchers have discovered a bizarre dwarf goat species that lived on the Spanish island Majorca, but that went extinct when human hunters arrived on the island about 3,000 years ago. The study says that the goat’s cold-blooded ways allowed it to survive on the resource-scarce island, as it could match its growth and metabolism to the available food supplies, but its sluggish movements made it easy prey for humans. In medical news, a research team investigating the dramatic failure of an HIV vaccine trial, in which vaccinated people seemed to be at higher risk of infection, has proposed a new theory for the failure. The study suggests that the common cold virus, which was used in the vaccine to carry HIV material around the body so the immune system could learn to recognize HIV, may have been at fault. The vaccine didn’t cause infection. But for people who have previously been exposed to this cold virus, its appearance may have triggered a gathering of immune cells called CD4 T-cells which were ready to fight it off. But those are the cells that HIV infects, so if people were then exposed to the HIV virus, the virus would have been presented with a ready availability of targets. Finally, an interesting study captured a snapshot of evolution-in-action on the Galapagos islands. A husband and wife team of evolutionary biologists is documenting what appears to be the emergence of a new species among Galapagos finches, the same birds that inspired Charles Darwin’s theory of evolution.
New England Journal of Medicine, November 19
Who can resist a story about brain-eaters that also has valuable medical and evolutionary lessons? A NEJM study describes a tribe in Papua New Guinea that used to engage in ritualistic cannibalism; when a member of the tribe died, the others ate the person’s brain as a mark of respect. The practice became a problem in the early 20th century, when some people became infected with a disease similar to mad cow disease and its human variant, Creutzfeldt Jakob disease. These fatal diseases are caused by misfolded proteins in the brain, so when the Fore people of Papua New Guinea consumed an affected brain the disease quickly spread. But a new study of living Fore people revealed that many are immune to the disease, which suggests that evolution has been acting quickly: Those people who had no resistance to the disease died off quickly, while people with resistance lived and multiplied. Researchers also hope to study the Fore people for clues on how to treat or prevent such diseases.
Proceedings of the National Academy of Sciences, November 10
The week’s most sensational news came from a PNAS study which heralded the repair of damaged rabbit penises by rebuilding crucial erectile tissue. The researchers proved that they could engineer new corpora cavernosas, the column of tissue that engorges with blood during male arousal, and the male rabbits demonstrated that their new parts worked just fine by mating and fathering offspring. While the technique isn’t ready for humans yet, researchers have high hopes that they’ll soon be able to help men who need penile reconstructive surgery. Spammers presumably have high hopes that they’ll soon be able to fill your inbox with messages touting the rabbit penis cure.
Human Reproduction, November 10
Since we have two stories that related to male sexual health, we’ll get them both out of the way. Then we’ll move on, we swear. This second study raised yet more troubling questions about the plastic chemical bisphenol A (BPA) that is found in everything from baby bottles to canned food linings. The researchers tracked the sexual health of more than 600 Chinese factory workers exposed to high levels of BPA, and found the men were four times more likely to suffer from erectile dysfunction and seven times as likely to have difficulty with ejaculation than factory workers who weren’t exposed to the chemical. Previous animal research has linked BPA to a host of other health problems, including fertility problems, cancer, and diabetes; this U.S. government-funded study seems to strengthen the case for taking the chemical off the market.
Proceedings of the National Academy of Sciences, November 3
Two studies in PNAS focused on the wildlife and landscape of East Africa. In the first, researchers looked back in history to Kenya’s infamous man-eating lions, which reportedly devoured 135 railroad laborers in 1898. The two lions were eventually shot, killed, stuffed, and shipped to Chicago’s Field Museum for display–which allowed researchers to analyze samples of the lions’ bones and fur. By comparing the isotopes present in the man-eating lions to those found in other lions, humans, wildebeest, and buffalo, the researchers could precisely determine the lions’ diet. The results brought the body count down considerably: The scientists estimate that one of the lions ate 24 people, while the other gobbled up 11. The second study looked ahead, and predicted that Mount Kilimanjaro, the highest peak in Africa, could lose its distinctive ice cap by 2022 due to global warming.
Journal of the American Medical Association, November 4
A new study of hospitalizations in California due to swine flu has highlighted a neglected risk factor: obesity. In the study group of patients whose weight was known, researchers found that 25 percent of the people were morbidly obese, although less than 5 percent of the U.S. population falls into that category. Researchers also found that 58 percent of these hospitalized patients were obese–in the population as a whole, about 34 percent of people are obese. The increased risks come partially from health problems associated with obesity, like heart disease, lung ailments, and diabetes. But physiological factors may also be to blame: The lungs of obese patients are squeezed by the abdomen pressing upward on the diaphragm.
Nature, November 5
A new astronomy study has solved a mystery that began brewing in 1680, when Britain’s first Astronomer Royal spotted a supernova in the constellation Cassiopeia. Supernova typically collapse into a super-dense object like a black hole or a neutron star, but for decades astronomers have looked for such an object at the center of the supernova remnant, to no avail. Now, a new examination suggests that there is indeed a baby neutron star there, but it escaped detection because it’s swaddled in an unusual atmosphere of carbon gas. Further studies of the 330-year-old star will give researchers insight into how such stars mature. Another study brings us from the macro to the micro, with an investigation into the evolution of bacteria. Researchers forced bacteria to evolve in constantly changing conditions, so that natural selection couldn’t produce microbes that were ideally suited to a single environment. Instead, researchers proved that the bacteria hedged their bets by evolving into a strain that could form several different shapes from the same genetic material. The will to survive: It’s an amazing thing.
Nature Nanotechnology, October
The carbon nanotubes that hold such technological promise may be more dangerous to human health than we realized, according to a new study. Lab mice that inhaled nanotubes were found to have the tubes in the outer linings of their lungs–that’s the same place where inhaled asbestos fibers settle and cause the slow-growing cancer known as mesothelioma. The researchers stress that they didn’t find any evidence of cancer in the mice that inhaled nanotubes during the 14-week study, but suggest that longer studies should examine the question further.
Journal of the American Medical Association, October 28
The new generation of antipsychotic drugs may be of enormous benefit to patients’ mental health, but they may take a toll of their bodily health. A study of children and adolescents taking the drugs for the first time found that the young patients added 8 to 15 percent to their weight in less than 12 weeks, leading researchers to caution that the pills may put patients at risk of diabetes and heart disease. The study focused on young patients in order to examine the drugs’ effects on people who had never tried them before, but researchers believe they have the same metabolic effects on adults.