 long assumed that these structures, like beetles’ horns, were outgrowths of cuticle. But on closer inspection, researchers report that the insects’ helmets are actually homologous to wings. Both structures attach to the body with joints and express the same genes during development. Like a pair of wings, a helmet forms from two pads of embryonic tissue. No other insect lineage has sported a third set of wing-like appendages over the past 250 million years. It seems that membracids have revived a long-silenced ancestral trait and put it to spectacular use.
Prud’homme, B., et al. Body plan innovation in treehoppers through the evolution of an extra wing-like appendage. Nature 473:83–86 (May 5)
Languages evolve so quickly that it’s hard to trace their ancestry more than about 6,000 years back. But a new study did so by stripping 504 modern languages down to their phonemes, the simplest sounds that convey meaning. (Miss and this differ by one phoneme.) The author found that African tongues had the most phonemes, whereas languages in South America and Oceania had the fewest. Thus, phonemic diversity, like genetic diversity, diminished along the path of prehistoric human migration away from Africa. This pattern suggests that a single mother tongue—spoken by the humans who left Africa more than 50,000 years ago—is the common ancestor of all languages spoken today.
Atkinson, Q. Phonemic diversity supports a serial founder effect model of language expansion from Africa. Science 332:346–349 (April 15)
If peahens (Pavo cristatus) tally eyespots on their suitors’ tail feathers, they do a sloppy job. As long as a male displays about 140 spots in his gaudy train, extras do not improve his chance of mating. Previous experiments reached conflicting conclusions about peahens’ preference for eyespots, and a new study revisited this classic case of sexual selection. Researchers confirmed that, among feral peafowl in North America, snipping out 20 spots wrecked males’ prospects for mating. But few peacocks were naturally so plain. Most displayed 144 to 169 eyespots—and within that acceptable range, hens relied on some other cue (still unknown to science) to rank their suitors.
Dakin, R., and R. Montgomerie. Peahens prefer peacocks displaying more eyespots, but rarely. Animal Behaviour (published online April 12)
Ash Under Scrutiny
Iceland’s Eyjafjallajökull volcano disrupted European travel last April, when airlines shut down for a week to avoid the ash plume. Now a battery of chemical and physical tests backs up that decision. Earth scientists conclude that the ash particles were unusually sharp, and hard enough to sandblast and obscure cockpit windows. Their glassy composition and powdery texture would have also damaged planes by melting in the interiors of jet engines. Had the ash fallen out in high concentration, its chemical coating would have threatened drinking water and its small size would have posed a breathing hazard. The authors suggest that their straightforward procedures could be used to quickly assess the health and mechanical risks of future eruptions.
Gislason, S. R., et al. Characterization of Eyjafjallajökull volcanic ash particles and a protocol for rapid risk assessment. Proceedings of the National Academy of Sciences 108:7307–7312 (May 3)
Nearly half of meat in U.S. supermarkets is contaminated with the infectious bacterium Staphylococcus aureus, a recent study reports. Ninety-six percent of those bacteria are antibiotic-resistant and more than half can withstand at least three different drugs. Each kind of meat has its own signature S. aureus genotypes, suggesting that the bacteria originated with the animals themselves rather than with human handlers. Researchers drew these conclusions from 136 samples of meat and poultry—including five species and 80 brands—purchased from grocery stores in five cities. Although cooking kills even superbugs, their prevalence in food suggests that the public-health implications may warrant further study.
Waters, A. E., et al. Multidrug-resistant Staphylococcus aureus in US meat and 