Nature, October 22
The top news this week was that a fossilized primate which got extraordinary hype last spring, when a TV documentary declared it a direct ancestor to humans and a “missing link,” probably didn’t play a major role in the evolution of humans, after all. A new study punched holes in the earlier work, arguing that the 47-million-year-old primate was nowhere near monkeys, apes, and humans on the primate family tree, but was instead part of the lineage that led to lemurs. This corrective study is gratifying to many evolutionary biologists who felt that the “missing link” study hadn’t been properly vetted, and was promoted so heavily in order to raise an audience for the TV show. Nature also had two interesting neuroscience studies this week. In the first, the memory problems of sleep-deprived mice were corrected by reducing the levels of one particular enzyme in the mouse hippocampus, the brain region involved in memory and learning. The study appears to point the way toward drugs for sleep-deprived humans, The second brain-related study identified, for the first time, a small group of neurons that process painfully loud sounds. Until now, researchers had been mystified as to the function of these neurons, which make up about 5 percent of the neurons in the inner ear.
Journal of the American Medical Association, October 21
An article in JAMA kicked up a bit of fuss by questioning the effectiveness of widespread screening for prostate and breast cancer. The authors note that prostate cancer screenings can turn up very slow-growing cancers that don’t pose a real threat, and say that treating such cancers can actually cause more harm to patients than leaving them be. They note a similar trend with the mammographies that screen for breast cancer. While the authors don’t go so far as to recommend the cessation of screening programs, they do ask for a better discussion of benefits versus risks.
Science, October 23
Amphibian populations are crashing around the world, and experts say that the chytrid skin fungus is one of the major culprits–but until now, no one understood how the fungus was killing frogs and toads and other creatures. A new study cracked the case by showing that the fungus interferes with frogs’ ability to absorb nutrients through their porous skin. The electrolytes that frogs usually get from their watery environments play a crucial role in muscle and nerve function; when their levels plummet, the frogs’ hearts shut down. While the new findings don’t offer any immediate hope for ways to treat fungal infections in the wild, researchers are determined to gather all the information they can about this killer.
New England Journal of Medicine, October 20
One of the most confounding stories in medicine over the past weeks has been the frustrating tale of the HIV vaccine that either showed the first real promise in preventing HIV infection, or was yet another dud–depending on how you look at it. In late September, researchers announced the results of a large clinical trial of the vaccine in Thailand, saying that people who received the vaccine were 31 percent less likely to get HIV. While the vaccine’s protection seemed limited, there was much rejoicing. But within weeks, other AIDS researchers declared that a different analysis of the trial’s results made it appear that the vaccine’s benefits were a fluke. The two sides have been hashing it out this week at the AIDS Vaccine Conference, drawing fresh evidence from the full trial results that were published in a study in NEJM.
PLoS ONE, October 21
Finally, on a lighter note: A new study has determined that the testosterone levels of male John McCain supporters dropped dramatically on Election Night 2008, when Barack Obama soundly beat their candidate. Men who supported Obama’s candidacy showed no corresponding boost in testosterone levels, and women’s hormone levels also stayed steady. The results were based on saliva samples taken at regular intervals on election night, and a surveys also revealed that the McCain supporters felt submissive, controlled, and unhappy. Researchers say the findings are proof that politics can affect men in the same way that physical contests for dominance do.