Discovered: Massive volcanoes caused widespread extinction 200 million years ago; men don't want to cheat with the wives of their friends; obese people share an altered gene; we remember things using social patterns.

Massive volcanoes caused widespread extinction 200 million years ago. We all know that the Earth's dinosaur population was wiped out about 65 million years ago, probably when an enormous asteroid struck the Earth's crust. But according to a pair of researchers at the Carnegie Institute and Columbia University, a series of "gigantic volcanic eruptions" led to the extinction of animal life about 145 million years before that, when dinosaurs weren't yet roaming around. By carbon-dating rocks, the researchers determined that volcanic activity had sent dense "sulfurous particles" into the atmosphere, blocking out the sun. "The eruptions may have caused climate changes so sudden that many creatures were unable to adapt," the researchers found, "possibly on a pace similar to that of human-influenced climate warming today." [Science]

Men don't want to cheat with the wives of their friends. We may no longer need Jonathan Franzen to dramatize the urgent confusion of marital infidelity. "After outgrowing teenage infatuations with the girl next door, adult males seem to be biologically designed to avoid amorous attractions to the wife next door," two professors at the University of Missouri discovered after measuring male subjects' levels of testosterone when exposed to "the marital partner of a close friend." (Richard Katz, the licentious but guilt-ridden anti-hero of Franzen's novel Freedom, would probably agree with the study.) The professors think the reaction is an evolutionary adaptation from an earlier era. "Men who were constantly betraying their friends' trust and endangering the stability of families may have caused a survival disadvantage for their entire communities." [Human Nature]

Obese people share an altered gene. It turns out that fighting obesity may require more than pure willpower. In a study of obese individuals, an epidemiologist at Georgia Regents University found that each individual's LY86 gene — which is associated with certain inflammatory disorders — was "methylated," or chemically transformed. Though it's unclear how exactly the LY86 gene is connected to an increased risk of obesity (for now, only correlation has been established), the epidemiologist is confident that further research will reveal how, exactly, that gene is altered — whether by genetic heritability, environmental factors, or even diet: "these types of details may help explain why some individuals grow obese with a bad diet and little physical activity while others don't." [American Heart Association]

We remember things using social patterns. Yes, that may seem obvious. But the way we aggregate disparate data in order to remember them is considerably nuanced, according to a Cornell sociologist who studied the way people form memories. "Humans keep track of social information not by rote memorization but with simplifying rules ... people recall social ties that both involve at least three people who know each other and kinship labels such as 'aunt' twice as well as they remember ties that do not, even though triad kinship networks are far more complex," said the sociologist, who tracked their memory retention of 300 subjects who were administered different versions of the same questionnaire. Those subjects recalled more when information mentioned social or familial ties, suggesting our social structures — family, friends, and so on — are a window into memory formation. [Scientific Reports]