What makes harmless little green grasshoppers turn into brown, crop-chomping clouds of swarming locusts? Serotonin, according to a study published this week in Science. Researchers from universities in the UK and Australia found that that neurotransmitter (a chemical compound that sends impulses between nerve cells and affects everything from sleep to aggression in humans) spurs a cascade of Dr. Jekyll-to-Mr. Hyde–like changes in at least one species of grasshopper — the desert locust (Schistocerca gregaria). This species is infamous for wreaking havoc from Africa to Asia. [More]

Spotting a Fake SmileAt least one good thing comes from a breakup: a better fake-smile detector. Social psychologist Michael Bernstein and his colleagues at Miami University found that people who felt rejected were better at discriminating between fake and real smiles. Researchers believe that a true grin indicates real emotions, such as cooperation, because some of the muscles we use–the ones around the eyes–are not under our conscious control. Our ancestors needed to be accepted in a group to survive, Bernstein says, so an outsider would not want to waste energy by acting on a fake reaction–or to miss a real opportunity to be included. –Rachel Mahan

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No Relief from Tsunami ThreatIn the devastating wake of the 2004 Indian Ocean tsunami, scientists rushed to investigate its cause and the potential for another killer wave [see “Tsunami: Wave of Change”; SciAm, January 2006]. They found that the tsunami resulted from a magnitude 9.2 earthquake off Sumatra’s western coast–specifically, at the Sunda megathrust, where one tectonic plate is diving below another. Scientists had conjectured two strong earthquakes there in 2007 might have relieved pent-up energy, thereby preventing another major quake.

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