Health & Science

Why fatherhood reduces testosterone

When men become fathers, their testosterone levels plummet—and the more time they spend with their children, the lower those levels fall. That finding, from a new study of more than 600 Filipino men, suggests that “women aren’t the only ones biologically adapted to be parents,” Northwestern University anthropologist Lee Gettler tells The New York Times. The five-year study found that men with higher testosterone levels were more likely to become fathers in the first place, perhaps because they pursued potential mates more aggressively. But nurturing children—by feeding, diapering, or playing with them—reduced a father’s hormone levels, making him “a little more sensitive to cues from his child” and less likely to stray, says Peter Gray, an anthropologist at the University of Nevada, Las Vegas. The link between fatherhood and lower testosterone likely evolved because early human families were more apt to survive when fathers took part in child-rearing. The study discredits “the idea that men were out clubbing large animals and women were staying behind with the babies,” says Gettler. “The only way mothers could have highly needy offspring every couple of years is if they were getting help.”

The boon of hearty laughter

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A good belly laugh has a rallying effect that no chuckle can match. A new British study shows that, like sex and exercise, the physical effort of uncontrollable laughter makes our brains release chemicals called endorphins, which relax us and relieve pain. It’s “the emptying of the lungs that causes” the feel-good effect, not just the thought of something funny, evolutionary psychologist Robin Dunbar tells BBCNews.com. He and his colleagues at Oxford University asked volunteers to watch either a comedy or a documentary, and then applied painful levels of cold or pressure to their arms. The volunteers who had laughed hard during their videos could withstand 10 percent more pain than those who’d only giggled or who hadn’t been amused at all. The study’s authors suggest that being able to really laugh gave humans a unique evolutionary advantage. Chimps and other primates laugh by panting, but only humans can guffaw intensely enough to get all the air out of their lungs and earn the endorphin benefit. Dunbar says belly laughing may have worked like “grooming at a distance” for our early ancestors, allowing them to maintain bonds within larger groups than their primate peers could.

Another Earth?

A newly discovered planet some 36 light-years away has the best odds yet of supporting alien life, astronomers say. The planet, HD 85512b, is about 3.6 times the size of Earth and orbits within its star’s Goldilocks zone—a region neither too hot nor too cold to harbor water. With enough cloud cover, temperatures on HD 85512b could range between 85 and 120 degrees Fahrenheit, making the surface “really muggy” but not uninhabitable, Lisa Kaltenegger, an astronomer with the Max Planck Institute in Germany, tells the Associated Press. The planet was one of more than 50 new worlds spotted using an instrument that detects the wobble of stars—a sign that a planet’s gravity is tugging against them. Nearly 20 of those planets appear to be “super-Earths,” meaning they’re not much larger than our orb and are hosted by stars very similar to our sun. Current telescopes aren’t powerful enough to actually see the planets, or to tell what they and their atmospheres are made of. But since the super-Earths are all located relatively nearby, in our Milky Way galaxy, scientists think future telescopes could let us search them for signs of life within the next 10 to 20 years.

SpongeBob leaves kids dazed

Watching fast-paced cartoons may harm young children’s learning abilities, at least in the short term. University of Virginia researchers had one group of 4-year-olds view a nine-minute clip of SpongeBob SquarePants, while another watched a more sedate PBS cartoon series and a third drew pictures with markers. Then they tested the children’s ability to remember numbers, follow rules, and resist tempting snacks. The SpongeBob watchers performed much worse than kids in the other two groups, and “were handicapped in their readiness for learning,” researcher Angeline S. Lillard tells WebMD.com. The effect is “immediate and strong,” she says, but it’s not clear how long it lasts. The study suggests that the kinds of TV programs kids watch could be just as important as how much they watch. Shows like SpongeBob that change scenes quickly and feature unrealistic characters could temporarily damage young kids’ ability to focus on real-life events. “It’s not that we can’t process these shows,” said Dimitri Christakis, a pediatrics professor at the University of Washington. But doing so “may come at a short-term cost so we can’t concentrate immediately afterward.”