Health & Science

How bears survive long winters

Hibernating bears have always posed a scientific puzzle. How do they keep from wasting away while not eating or drinking for seven months? To find out, University of Alaska scientists studied five wild black bears they installed in specially built wooden dens, recording the bears’ vital signs for every second of their winter slumber. The bears’ secret: While hibernating, they slow their metabolism to just 25 percent of the normal rate—a more dramatic change than is seen in any other hibernating animal. By essentially shutting down their metabolism, while keeping body temperature relatively stable, bears can go the entire winter without eating, drinking, urinating, or defecating. In fact, the researchers found, the bears’ hearts sometimes stopped beating for up to 20 seconds as they exhaled (and sometimes snored). Figuring out how bears go into suspended animation could lead to new ways of keeping people alive after accidents or heart attacks, and might also enable astronauts to survive long voyages in space, study author Brian Barnes tells BBC.com. “It’s just this alternative way of being,” he says, “that we didn’t know was possible.”

Pollution speeds evolution

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Natural selection normally happens over thousands of years, but it took just 50 for pollution to transform a fish species in the highly contaminated Hudson River, investigators have found. The PCBs and other toxins that General Electric plants started dumping into the Hudson in 1947 used to kill most of the river’s Atlantic tomcod while they were still young. Recent surveys, though, show that the bottom-feeding fish in the still-polluted waters are now living much longer than before. Researchers found that 99 percent of Hudson tomcod now have a genetic mutation that prevents the pollutants from harming them, and that the gene shows up in only 10 percent of tomcod from clean waters. “It’s an example of how human activities can drive evolution,” study co-author and Woods Hole Oceanographic Institution biologist Mark E. Hahn tells ScienceDaily​.com. The mutation allows the Hudson tomcod to survive and reproduce by binding extreme levels of PCBs in their fat—but not without a price to the environment at large. The Hudson tomcod’s adaptation means the striped bass that prey on them ingest heavy doses of stockpiled toxins, pushing pollutants up the food chain. In other words, warns co-author Isaac Wirgin, “Any evolutionary change at this pace is not a good thing.”

Curing baldness by accident

Researchers studying the effects of stress on mice may have inadvertently stumbled upon an elixir for balding humans. The scientists had genetically engineered rodents to overproduce a stress hormone, which incidentally caused them to lose most of the fur on their backs. When the researchers injected the mice with a chemical compound meant to block stress damage to their guts, they were startled to find that it completely replenished their fur. “Almost 100 percent of the mice responded,’’ study author Million Mulugeta tells Reuters​.com. “The hair grows back fully. It is a very dramatic effect.” Subsequent tests showed that the compound, astressin-B, was able to not only reverse hair loss but also prevent it. It even changed the pigment of the mice’s skin, indicating a potential for turning graying hair back to its original color. Experts caution that if it works on humans at all, astressin-B may only be able to combat balding caused by stress or aging, as opposed to genetics. Mulugeta, though, has applied for a patent and is optimistic. “We certainly intend to continue the research,” he says.

Cell phones and the brain

Pressing your cell phone to your ear can at least temporarily alter your brain. That’s the disturbing finding of researchers from the National Institutes of Health, who scanned the brains of 47 volunteers while they had cell phones attached to each side of their heads. During a 50-minute call, activity in the brain’s neurons closest to the antenna increased by 7 percent—a significant amount. “We have no idea what this means yet or how it works,” study author Nora Volkow tells Wired, “but this is the first reliable study showing that the brain is activated by exposure to cell phone radio frequencies.” Previous studies have found contradictory evidence about whether mobile-phone radiation can lead to a higher incidence of brain cancer; many researchers have insisted there is no way the weak radiation emitted by the phones could affect biological tissue. But the NIH study shows that there is, in fact, an interaction, raising the question: Could the neurological stimulation shown by the scans be causing dangerous inflammation and brain-cell damage over time? “You don’t have to wait around on us for the answers,” Volkow says. She strongly recommends using a headset or speakerphone to keep cell phones away from your head.