Health & Science

Engineered plants that eat poisons; Your bacteria like truffles, too; How mussels saved humanity; More sex, more sperm; The seductive power of rumor; and Health scare of the week Super-staph on the march.

Engineered plants that eat poisons

By inserting genes from a rabbit’s liver into plants, scientists have engineered two new species of flora that can “digest” toxins and cleanse polluted soil, says National Geographic News. This breakthrough in genetic engineering raises the possibility that industrial wastelands could be recovered for use by covering them with specially designed plants and trees. Researchers at the University of Washington created one of the new species by inserting a string of genetic code from a rabbit’s liver into the genome of an aspen tree. The tree now produces a liver enzyme that digests the industrial chemical TCE, a known carcinogen that can contaminate groundwater. In a similar project, European and Canadian biologists modified a cabbage-related weed to absorb and neutralize the cancer-causing explosive RDX. When planted in military firing ranges, these modified weeds absorbed more than 90 percent of the RDX. Plants are terrific detoxifiers because they’re built to absorb groundwater and to release harmless waste, and they require only the energy of the sun to do their work, says Doug Gurian-Sherman of the Union of Concerned Scientists. But there is a downside. If we were to release free-flowering genetically modified plants into the environment, we might not be able to control their spread. “I think we’re playing to some extent a game of roulette here,” Gurian-Sherman says. “If they do [escape and] cause problems, we’re pretty much going to be stuck with them

Your bacteria like truffles, too

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Craving chocolate? You might be responding to a demand from billions of chocoholics living in your gut, says the Associated Press. When researchers examined 11 men who craved chocolate daily and 11 men who rarely ate chocolate, they found major differences in what kinds of bacteria lived in their guts. Bacteria that thrive on chocolate can be found in great abundance in chocoholics, but aren’t very common in people who are indifferent to chocolate. Researchers aren’t sure, though, whether cocoa-loving bacteria cause the chocolate cravings, or whether they simply flourish in a high-chocolate diet.

How mussels saved humanity

The earliest humans survived a prehistoric Ice Age by living off mussels and other shellfish, says LiveScience. Artifacts found in a cave in South Africa indicate that people began eating shellfish 164,000 years ago—at the dawn of human history. A band of Homo sapiens lived in that cave for several generations, leaving behind pigments that had been used as paint or body dyes, little stone blades, and the shells of mussels, whelks, and giant periwinkles. At that time, the global climate was in a period of extreme cold and widespread glaciers, making food scarce. The shelter of the cave—close to the warm currents of the Indian Ocean—and the nearby seafood probably kept our species from perishing in a hostile climate. “The shellfish,” says researcher Curtis Marean of Arizona State University, “may have been crucial to the survival of these early humans.”

More sex, more sperm

Couples who are trying to get pregnant should have as much sex as possible, says a new study. The suggestion may seem an obvious one, but many couples actually abstain from sex on the belief that this will enable the man to build up a surplus of sperm for the time when a woman is at her most fertile. “I remember one couple in which the woman would only let the man ejaculate when she was in her fertile period,” Dr. Allan Pacey tells “So the poor chap was going without for almost a month at a time.” Such strategies are counterproductive, Dr. Pacey says, and can actually harm the quality of sperm. Having sex every day can increase a male’s sperm production by 20 percent to 30 percent, and will also clear out old, damaged sperm to make way for the fresh swimmers right off the assembly line.

The seductive power of rumor

When people hear nasty gossip, they put so much stock in it that they’ll even ignore the evidence of their own eyes or ears, says The New York Times. Evolutionary biologists designed an experiment to test the power of gossip: A philanthropy game allowed players to give other players money based on a recipient’s rumored reputation. When the players were told a recipient was generous and friendly to other players, they were far more likely to give that person money. Conversely, when the recipient’s reputation was that of a “Scrooge,” other players were far less likely to give him money. No surprise there. But this pattern remained true even when the players were able to see written records showing that the supposedly cheap recipient had been quite generous or that the generous person had been miserly. “People only saw the gossip,” says researcher Ralf Sommerfeld of Germany’s Max Planck Institute. “They really reacted to it.” Human beings, he says, appear to be wired to base their decisions on rumors, gossip, and what other people say—not on a rational assessment of the evidence.

Health scare of the week

Super-staph on the march

A supervirulent strain of drug-resistant staph bacteria is killing more people than AIDS, says a new federal report. MRSA, an antibiotic-resistant strain of the common Staphylococcus bacterium, infected more than 90,000 people last year and killed 19,000. This year, the report says, more Americans were killed by MRSA than by the AIDS virus. “This is a significant public health problem. We should be very worried,” CDC epidemiologist Scott K. Fridkin tells The Washington Post. About 85 percent of the nasty staph infections occurred in hospitals, nursing homes, or other health-care facilities, but the superbacteria appears to be making its way into the community. Schools, locker rooms, and other crowded places could be incubators, so health officials have warned that anyone visiting them should wash their hands thoroughly and not share personal items such as towels. Super-staph has evolved in response to the overuse of antibiotics and to patients’ tendency to stop treatment before they’ve completely cleared an infection. It usually begins as a skin infection.

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