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18 | NewScientist | 2 March 2013 BLAME it on the bunnies. The debate over what Neanderthals ate, and how it may have led to their demise, has turned to rabbits. Which, it is now claimed, they did not feast on. Signs that our extinct cousins hunted dolphins and seals were presented in 2008 as evidence of their sophistication. But, experts claimed in 2009, they weren’t clever enough to catch fish or birds – which could have given our ancestors an edge. Then came the discovery of fish scales and feathers on Neanderthal tools. Now, John Fa of the Durrell Wildlife Conservation Trust in Trinity, Jersey, says the remains in caves around Europe became dominated by rabbits rather than large game around the time Neanderthals went extinct (Journal of Human Evolution, doi.org/kkn). Lost continent beneath Mauritius THE sands of Mauritius are hiding a secret: deep beneath them lurks an ancient continent. Trond Torsvik and colleagues at the University of Oslo, Norway, analysed grains of zircon found on the island’s beaches, measuring the balance of lead and uranium isotopes to work out their age. This showed that some formed almost 2 billion years ago – although the volcanic island is no more than 65 million years old. So where did the grains come from? Torsvik thinks they are from fragments of continental crust beneath Mauritius that melted as the volcanic island formed. The team have named the proposed continent Mauritia (Nature Geoscience, DOI: 10.1038/ ngeo1736). It’s a reasonable idea, says Michael Wysession at Washington University in St. Louis, Missouri. “It’s hard to imagine how zircons could be there any other way.” Chilly secret to monarch migration revealed ONE of the most spectacular events in the natural world is about to begin. In early March, having spent the winter in Mexico, millions of monarch butterflies (Danaus plexippus) will return north to their breeding grounds in the US. For the first time, we may know why. The monarchs come south in the autumn to escape the freezing North American winters, and leave Mexico to fly north again come spring. No one has ever figured out what triggers them to leave the relative warmth of Mexico. It’s all down to temperature, says Steven Reppert of the University of Massachusetts Medical School in Worcester. JOEL SARTORE/NGS IN BRIEF If you can’t catch a rabbit, the end is nigh It’s not clear why they would have had more trouble changing prey, says Fa. They may have been less able to cooperate. Rather than using spears, early humans probably surrounded a warren and flushed out rabbits with fire, smoke or dogs. But Bruce Hardy of Kenyon College in Gambier, Ohio, says Fa takes the interpretation too far. Humans may have eaten more rabbits than Neanderthals, but neither would have exclusively eaten meat, he says. Reppert captured 12 southbound monarchs in the autumn and housed them in conditions that mimicked a Mexican winter, with short days and temperatures hovering just above freezing. When he released them 24 days later they flew north, even though it was the wrong time of year. He repeated the experiment with longer days, and again the butterflies flew north. “It really was the cold temperature that was flipping them round,” says Reppert (Current Biology, doi.org/kkr). If the northbound leg is set off by cool temperatures, it may be affected by climate change. “It has to be cold enough to cause the switch [of direction],” Reppert says. If conditions in Mexico are too warm, the monarchs might think it is still autumn and head further south. Or the iconic migration may stop altogether. IF IT looks too good to be true, it probably is. Several “herbal remedies” for erectile dysfunction sold online actually contain the active ingredient from Viagra. Michael Lamb at Arcadia University in Glenside, Pennsylvania, and colleagues purchased 10 popular “natural” uplifting remedies on the internet and tested them for the presence of sildenafil, the active ingredient in Viagra. They found the compound, or a similar synthetic drug, in seven of the 10 products – cause for concern because it can be dangerous for people with some medical conditions. Lamb’s work was presented last week at the American Academy of Forensic Sciences meeting in Washington DC. Herbal Viagra gets a synthetic boost
