Could a stopwatch predict heart health?
What are your odds of falling victim to heart problems as you age? There’s now a simple way to find out: Time yourself running a mile. After studying more than 66,000 people between the ages of 20 and 90 over a period of 36 years, researchers at the University of Texas Southwestern Medical School have concluded that fitness in middle age is as strong a predictor of heart health as commonly known risk factors like high blood pressure and high cholesterol. And the best measure of fitness is “the speed at which you can run,” lead researcher Jarett D. Berry tells The New York Times. “Heart disease risk increases markedly for every minute longer it takes you” to complete a mile. Men in their 50s who can run a mile in eight minutes, and similarly aged women who can do so in nine, have a lifetime heart disease risk of only 10 percent, the study concluded. Men who take more than 10 minutes and women who need more than 12 are three times more likely to suffer problems like heart attack and stroke. Berry says the findings show that many people who think they’re active probably aren’t pushing themselves hard enough. “Getting off the couch is the first step,” he says, “but vigorous activity has a much more dramatic effect” on future heart health.

It’s raining microbes
Could bacteria in the sky affect the weather? The idea is not as outlandish as it sounds. New research provides strong evidence that microbes in the clouds serve as the nuclei around which water droplets, snow, and hail form. Scientists have traditionally thought that precipitation coalesced mostly around airborne minerals and dust particles. But when microbiologists at Montana State University dissected golf-ball-size hailstones that fell on campus last year, they found high concentrations of bacteria at their cores—“the first part of a hailstone to develop,” study author Alexander Michaud tells LiveScience​.com. And that’s no accident, says Brent Christner, another scientist in the growing field of bioprecipitation, which studies the links between germs and weather. He discovered that one common species of bacteria contains a special protein that encourages snow to form at significantly warmer temperatures than usual. Such an “ability to produce precipitation,” he says, is an evolutionary advantage for bacteria that feed on plants, as it lets them “hitchhike on the water cycle” to get from host to host.

Brainier by a nose
In evolutionary terms, we may have our sense of smell to thank for our smarts. New research shows that prehistoric mammals evolved larger brains in order to better detect scents, “and once you’ve got a big brain you can do all kinds of things with it,” Timothy Rowe, a paleontologist at the University of Texas, tells Nature.com. Rowe and colleagues examined the skulls of two tiny 190-million-year-old fossils, believed to be those of the earliest mammals’ direct predecessors. They found evidence of a huge increase from still earlier fossils “in the size of the olfactory bulbs,” or the brain regions that process smell. That growth spurt was likely the catalyst for an overall brain upgrade: Today, mammals, including humans, have brains up to 10 times larger for their body size than reptiles do. Co-author Zhe-Xi Luo thinks being able to sniff out food was “far more important” to our ancestors than any other sense because it would have let them hunt at night, when reptilian predators were sleeping.

Why we love gossip
There’s a sound evolutionary basis for why the National Enquirer and TMZ.com are so popular. A new study shows that humans are hardwired to pay special attention to scandals and other negative information about other people. Researchers at Northeastern University showed volunteers an array of faces, some of which were linked to negative gossip, such as “threw a chair at his classmate.” They then presented a series of those faces to just one eye of each subject, while the other eye viewed an unrelated image. The brain can handle only one image at a time, and when faces that were linked to ugly rumors appeared, the subjects’ gazes lingered longer on those than on ones they’d been led to consider nice or neutral. That reflex probably exists “for good evolutionary reasons,” Frank McAndrew, a psychology professor at Knox College, tells NPR.org. Heeding negative gossip probably helped early humans avoid untrustworthy or threatening members of their own tribe or other tribes. “Our intense interest in gossip is not really a character flaw,” McAndrew says. It’s a tool for survival.