Health & Science

How caffeine sharpens your memory

Coffee is one of the most popular beverages in the world for lots of reasons, including that it gives people a pleasant lift in the morning. New research shows that it also helps their memory. Researchers had 160 people who were not regular coffee drinkers look at pictures of objects; five minutes later they gave them either a placebo or a tablet containing 200 milligrams of caffeine—about the amount contained in a strong cup of coffee. The next day, participants were shown a broader set of images and asked to identify which ones were new, old, or similar. The caffeinated group was more likely to recognize slight differences in the pictures, such as a yellow rubber duck that was fatter than the one they’d seen the day before. “Without these tricky similar items, we would have found no effect of caffeine,” University of California, Irvine, neuroscientist Michael Yassa tells Forbes.com. “However, using these items requires the brain to make a more difficult discrimination—what we call pattern separation, which seems to be the process that is enhanced by caffeine.” It’s that form of memory that people use, for example, to recall where they last parked the car. Caffeine’s effect depends on the dosage, however: Researchers found that 100-milligram tablets didn’t improve memory, while 300-milligram doses caused headaches and jitteriness.

The journey from fins to feet

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The fossil of a 375 million-year-old aquatic creature makes the case for a new theory of how fish evolved into legged animals, suggesting that they developed hind limbs as an adaptation for shallow water rather than once they had migrated to land. Tiktaalik roseae, a transitional species that looked like a cross between a fish and a crocodile, had gills, scales, and fins but also a robust rib cage, primitive lungs, and weight-supporting forefins. The first partial fossils of the beast were discovered in the Canadian Arctic in 2004, but more recent discoveries of its hindquarters reveal a flexible hip joint and a pelvic girdle large and robust enough to support strong rear limbs. “It’s clear that the emphasis on hind appendages and pelvic-propelled locomotion is a trend that began in fish,” University of Chicago evolutionary biologist Neil Shubin tells The New York Times. The findings challenge the “front-wheel drive” theory, which holds that the transition to a terrestrial existence began when fish crawled from the water using enhanced front fins, and evolved rear limbs only afterward. With its “four-wheel drive,” Tiktaalik would have been able to walk on a lake floor, paddle, and make brief trips onto land.

Teen pregnancy reality check

Critics blasted the MTV reality show 16 and Pregnant for supposedly glamorizing teen pregnancy. But a new study says the show had a major impact on reducing teen pregnancy by realistically depicting how it changes the young mothers’ lives—a finding that shows just how strongly young people’s decisions are influenced by the media. The study, by the National Bureau of Economic Research, found that the show and its spinoffs reduced the teen birthrate nationwide by nearly 6 percent between its premiere in June 2009 and the end of 2010. In its highly watched episodes, 16 and Pregnant showed teen moms struggling with angry parents, lost sleep, distant boyfriends, and money problems. Researchers found that geographic areas with high MTV viewership experienced a faster decline in teen pregnancy rates than other areas. “You can have a middle-aged teacher telling teens about it in a classroom—or you can see firsthand how people’s lives change,” Wellesley College economics professor Phillip Levine tells the Los Angeles Times. All told, the program may have prevented more than 20,000 births to teen mothers in 2010.

Why athletes trash-talk

The trash-talking of athletes isn’t mere macho posturing. Angering an opponent can sometimes give a competitor an edge, and a new study has found that people have an intuitive sense of when that strategy works best. Researchers at the University of California, San Diego, had 260 men compete in one of two one-on-one games. The first tested the strength of their handgrips, while the other, a computerized target-shooting game, called for mental focus. Beforehand, one member of each pair was given the option to anger his opponent by assigning him 20 minutes of boring busy work to complete after the test. When the opponent was told about the assignment, his anger generally led him to fare better in the strength test but worse in the mental test, supporting the notion that anger boosts strength but clouds mental acuity. Participants seemed to intuitively understand this, opting to anger their opponents far more often before the mental test than before the strength test. In sports, “using emotions is not a mistake,” behavioral economist Uri Gneezy tells LiveScience.com. “The real art of using emotions is knowing how to manipulate other people’s emotions.”