Health & Science

Lucy walked upright

A 3.2-million-year-old foot bone—from a contemporary of the famous fossil skeleton “Lucy”—could drastically alter our evolutionary time line, says the Los Angeles Times. Ever since scientists unearthed Lucy, in 1974, they’ve believed that members of her prehuman species likely spent much of their time in the trees, while a different species, Homo erectus, was the first to walk upright, some 70,000 to 1.8 million years ago. That was just a guess, though, since Lucy’s skeleton lacked feet. Recent analysis of a newly discovered foot suggests that Lucy and her Australopithecus afarensis kin “were fully human-like and committed to life on the ground,” study author and University of Missouri professor Carol Ward tells the Associated Press. Found in Hadar, Ethiopia, the metatarsal proves that A. afarensis had stiff feet with shock-absorbing arches like we do—as opposed to flat, flexible tree-climbing feet like apes. While upright mobility would have slowed A. afarensis down, it would also have freed the early hominid’s hands for carrying food, weapons, and children—a major adaptive advantage. If the researchers’ interpretation is correct, it pushes back by 2 million years the development of upright walking among our hominid ancestors.

How the mighty flea jumps

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How do fleas jump so high? The tiny insects can blast off with more than 30 times a space shuttle’s acceleration, bound 38 times higher than the length of their bodies, yet land with precision. But a flea jump happens so fast that the exact mechanics have puzzled scientists for decades. Using high-speed cameras and computer analysis, Cambridge University scientists have cracked part of the puzzle. They found that the insects crouch like sprinters before takeoff, storing energy in their bodies, like catapults. Their feet form the base of a lever that, when a flea releases its spring-like legs, drives it forward and up. Scientists, though, are still trying to figure out how fleas lock their two spring-loaded legs prior to liftoff and release them at exactly the same instant to avoid flying off-course. “If you’re half a millisecond off, you’re done,” study author Gregory Sutton tells The New York Times. If scientists figure out that piece of the puzzle, he said, they might “learn how to build robots that could leap over rough terrain.”

Hearing loss linked to dementia

Losing your hearing raises the risk that you’ll develop dementia, a new study finds. Researchers at Johns Hopkins Hospital tested the hearing of more than 600 mentally sharp adults between the ages of 36 and 90, and then tracked them over 15 years. They found that a loss of hearing was accompanied by a much higher likelihood of developing Alzheimer’s or another form of dementia. Every 10 decibels of hearing lost made participants 20 percent likelier to develop cognitive problems. Subjects who lost nearly all their hearing were five times more likely to develop dementia. Study author Frank R. Lin tells Health.com that he and his colleagues aren’t yet sure how to explain the link, but they say it’s possible hearing loss is a cause rather than just a symptom. Hearing difficulties may push people to become socially isolated—which has itself been tied to dementia—or strain the brain’s ability to process other sensory information. So could hearing aids and other treatments help ward off mental decline? For the 30 million Americans with hearing impairment, Lin says, that’s the “50-billion-dollar question.”

Fiber can prolong your life

Most of us are not getting nearly enough fiber—and the difference could mean life or death. A new study by the National Institutes of Health of 400,000 men and women found that those who ate high-fiber diets were 22 percent less likely to die over a nine-year period than those on the low-fiber end of the spectrum—which is the majority of Americans. On average, we consume only about 15 grams of fiber per day (roughly the amount in five pieces of whole-wheat bread), but health experts say women should get 25 grams, and men 38. While doctors have long touted roughage’s beneficial effect on heart health, the study showed that fiber may also significantly reduce your odds of succumbing to respiratory and infectious diseases, and, for men, cancer. “The benefits of fiber are broader than what had been anticipated or previously studied,” Dr. Frank Hu, a professor at the Harvard School of Public Health, tells CNN.com. Researchers say those benefits may come from the additional micronutrients, vitamins, and antioxidants in whole grains such as brown rice and oatmeal. To ward off disease and extend life, researchers recommend eating a wide variety of fiber-rich foods—whole grains, vegetables, fruits, and legumes.