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]