American Scientist

This roundup summarizes some notable recent items about scientific research, selected from news reports compiled in Sigma Xi’s free electronic newsletters.

Cosmic Merger

A supermassive black hole resides at the center of nearly every large galaxy. As galaxies collide, their black holes should attract one another and eventually unite. But telltale pairs of nearby black holes have been hard to find. Now astronomers think they’ve spotted just such a duo, separated by only 0.3 light years and orbiting one another every century. The evidence is a quasar that emits a beam of light containing not one, but two hydrogen emission spectra of slightly different colors. This likely means the quasar contains two black holes, but only continued vigilance can completely eliminate the alternative: that astronomers caught two quasars crossing the same line of sight.

Boroson, T. A., and T. R. Lauer. A candidate sub-parsec supermassive binary black hole system. Nature 458: 53–55 (March 5)

Romanov Case Closed

The Romanov dynasty ended in 1917 when Czar Nicholas II ceded his throne during the Russian Revolution. The Bolsheviks executed Nicholas and his family the following year. But the world has embraced romantic rumors that two of the czar’s children, Alexei and Anastasia, escaped. Forensic DNA analyses have finally laid the legend to rest. Researchers sequenced DNA from bones in two unmarked graves and then compared the sequences to each other, to the Romanovs’ living relatives, and to bloodstains on a shirt Nicholas once wore during a failed assassination. The results account for the czar, his wife, and all five of their children. Anastasia impersonators are discredited once and for all.

Coble, M. D., et al. Mystery solved: The identification of the two missing Romanov children using DNA analysis. PLoS ONE 4(3): e4838 (March 11)

Headache? It Really Is the Weather

Migraine sufferers often blame the weather for their pain. But until now, no large medical study has solidly backed their claims. Mixed results of previous studies made researchers wonder whether it was air pollution, not weather, that brought on migraines. They analyzed medical records of more than 7,000 patients who came to a Boston emergency room for severe headaches over the course of 7 years. The study compared temperature, air pressure, and levels of four air pollutants on the day before a patient’s headache onset and on headache-free days in the same month. Pollution didn’t seem to matter—but the risk of a migraine escalated 7.5 percent for every 5 degrees Celcius increase in temperature.

Mukamal, K. J., et al. Weather and air pollution as triggers of severe headaches. Neurology 72: 922–927 (March)

Wired to Believe?

Children tend to explain natural phenomena in terms of purpose. For instance, kids have claimed that birds exist in order to make music. But a new experiment suggests that a similar impulse is ingrained in adults who should know better. Researchers drilled 230 undergrads by flashing sentences on a computer screen for 3.2 seconds, 5 seconds, or with no time limit. The more the students rushed, the more they endorsed false teleological statements such as “earthworms burrow to aerate the soil.” But even with time to think—and regardless of religion—students often agreed with statements that the earth is intended to support life. This inclination, the authors argue, may lend momentum to creationist and intelligent design movements.

Kelemen, D., and E. Rosset. The human function compunction: Teleological explanation in adults. Cognition 111: 138–143 (April)

Galloping Back in Time

Agriculture, warfare, transportation, commerce—domestic horses transformed many facets of human culture. New evidence suggests that the transition to horseback was underway a full millennium earlier than previously thought. Researchers studied tools and horse remains from four Kazakh archaeological sites dating to 3500 B.C. There, ancient horse teeth had wear marks likely caused by bridle bits, and the slender equine foot bones resembled those of domestic horses rather than wild ones. Pottery shards at the same sites bore traces of horse milk fat—a sure sign that the villagers’ horses were tame.

Outram, A. K., et al. The earliest horse harnessing and milking. Science 323: 1332–1335 (March 6)

Cozy Caves for Sick Bats?

For the past three winters, a fungal infection has stricken bats in the northeast U.S. The disease causes white patches on the animals’ skin, makes them hibernate fitfully, and kills more than 80 percent of little brown bats (Myotis lucifugus) in affected areas. A new mathematical model supports the idea that troubled hibernation is the cause of death. When bats rouse in winter, they burn extra energy to stay warm; if they do so too often, they starve. But the model also suggests a temporary solution: Provide heated bat-boxes for hibernation, so restless bats burn fewer calories just to stay warm. This winter, the authors plan to test whether bats will really use the boxes.

Boyles, J. G., and C. K. R. Willis. Could localized warm areas inside cold caves reduce mortality of hibernating bats affected by white-nose syndrome? Frontiers in Ecology and the Environment (published online March 5)

First Photosynthesis

The first photosynthetic bacteria pumped Earth’s atmosphere full of oxygen, a metabolic waste product essential for much of today’s life. Despite its importance, the moment of earliest photosynthesis has been hard to pinpoint, and estimates range from the widely accepted 2.4 billion years ago to a more controversial 3.46 billion years ago. Evidence that old can be shaky, but the 3.46-billion- year scenario gains strength with the discovery of hematite crystals of that age in Australian rocks. The crystals formed when iron oxidized underwater—implying that the water was oxygen-rich. If so, photosynthetic bacteria would have been the most likely source.

Hoashi, M., et al. Primary haematite formation in an oxygenated sea 3.46 billion years ago. Nature Geoscience (published online March 15)