Great Whites Didn't Descend from 'Megasharks'; Oxytocin Makes Men More Monogamous

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Discovered: Shark evolution unpacked; hormone puts a leash on cheating men; rogue planet discovered; MRSA outbreak reigned in.

Great whites didn't evolve from "megasharks," though they probably would've liked to count such an awesomely named species among their ancestors. For the last 150 years, a theory linking present-day great whites to prehistoric megatooth sharks like the Megalodon. A team led by Professor Dana Ehret of Monmouth University found instead that great whites started small, locating intermediate features shared by today's great whites and smaller mako sharks from the past. They were able to make this call based on full sets of jaw bones, rare in a field where scientists often have to rely on teeth alone to trace lineage. "We've bolstered the case that white sharks are just highly modified makos," says Ehret. "It fits the story now." [BBC News]

Men with high oxytocin levels stay faithful. "Why Men Cheat," was the name of one particularly sensational episode of Oprah. For many different reasons, we're sure, but one of them might have to do something with hormonal balance. A new paper in the Journal of Neuroscience shows that men with higher levels of oxytocin—a neurochemical that has been linked with trust and bonding—are less likely to cheat. When experimental subjects received doses of oxytocin, the married men among them actually put more distance between themselves and attractive women to avoid intimacy. Maybe General Petraeus simply didn't have enough oxytocin coursing through his body? [Los Angeles Times]

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"Homeless" planet found. Astronomers find rogue planets from time to time, big interstellar masses that hurtle through space with no star to orbit. But the one just discovered by University of Montreal researchers and their colleagues is a particularly roguish rogue planet. Because it's the first body that scientists have been able to distinguish from a brown dwarf, the term for failed stars. "This group is unique in that it is made up of around thirty starts that all have the same age, have the same composition and that move together through space. It's the link between the planet and AB Doradus that enabled us to deduce its age and classify it as a planet," says Lison Malo. [University of Montreal]

MRSA outbreak halted. Antibiotic-resistant bacterial infections continue to pop up in hospitals around the world, but one hospital in the UK was able to stamp out an outbreak by sequencing the MRSA genome. Sharon Peacock at the Wellcome Trust Sanger Institute used whole genome sequencing to quash a flare-up in the special care baby unit of Cambridge's Rosie Hospital. "The original investigation was inconclusive, we couldn't say whether it was an outbreak or not," says co-researcher Julian Parkhill. Through whole genome sequencing, "we were immediately able to say that they were an outbreak ... and it was almost certain that transmission had occurred on the ward." They were able to trace the outbreak back to one specific hospital worker, who was treated with an antiseptic before being allowed to go back to work. Following that precaution, no new infections have been reported. [New Scientist]

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