Health & Science

Our bodies, our microbes

Our bodies contain 10 times more bacteria than human cells, and those resident microbes may rule our mental and physical health. That’s the conclusion of researchers who for the first time have mapped up to 99 percent of the microbes that live, more helpfully than harmfully, in the human body. Using DNA sequencing on samples gathered from 242 healthy volunteers, they discovered that we each host 100 trillion bacteria of 10,000 types. As much as six pounds of our body weight is bacteria. Each person has a unique microbiome, or balance of different types of microbes. “These microbes are part of our evolution,” New York University microbiologist Martin Blaser tells NPR.org. “They are very important in human health and probably human disease as well.” Helpful bacteria assist in the digestion of food, train the immune system, and aid in keeping harmful bacteria from taking root. Researchers hope that maps of healthy microbiomes will allow doctors to identify bacterial imbalances that can cause infections, mood disorders, obesity, and other medical problems—and offer clues on how tweaking a patient’s microbial makeup could address them. The next challenge, Washington University biologist George Weinstock says, is to figure out how microbes “talk to our human cells” and how “human cells talk back to them.” That conversation, he says, “makes us who we are.”

The folly of Bonnie and Clyde

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Robbing a bank is a terrible get-rich-quick scheme—even if you don’t get caught, Time.com reports. British economists conducted a first-ever cost-benefit analysis of bank robbery, using confidential data from U.K. and U.S. authorities, and concluded that “the return on an average bank robbery is, frankly, rubbish.” British robbers score an average of $19,800 per thief per heist—about six months’ wages for the average British office worker; Americans nab only about $4,000 each per job. Only 66 percent of robberies are successful, and every additional attempt increases the chances you’ll be caught: By stickup No. 4, you’re more likely to land in jail than to be free to rob again. High risks and low returns may be one reason bank robberies have declined in the U.S. in recent years: Robbers made off with about $57 million in 2007, compared with a mere $33 million last year. Carrying a weapon can increase the odds of a large windfall, and “the bigger the gang, the greater the take,” the economists say. But on the whole, “as a profitable occupation, bank robbery leaves a lot to be desired.”

An oasis on Titan

Saturn’s moon Titan may harbor a vast underground ocean of liquid methane that could be a crucible for life. Researchers came to that conclusion after studying intriguing images from NASA’s Cassini spacecraft, which showed what appears to be a shallow methane lake about the size of Utah’s Great Salt Lake near the otherwise dune-covered equator of Titan. The sighting of the oasis and nearby methane swamps “was completely unexpected,” University of Arizona astronomer Caitlin Griffith tells the Associated Press. Unlike the hundreds of lakes at Titan’s polar regions, she says, liquid “at tropical latitudes” should evaporate too quickly for standing puddles to form. That suggests that the equatorial lake is fed by a subterranean aquifer of methane. Since methane contains carbon and hydrogen, two of the building blocks of life as we know it, the presence of an underground methane ocean would increase the likelihood that Titan hosts some form of life. Titan and Earth are the only objects in the solar system with a cycle of rain and evaporation.

Cougars headed to the Midwest

Mountain lions are making a comeback, even in relatively flat regions of the Midwest. Though the big cats, also known as cougars, once ranged all over North America, hunting and habitat loss rendered them virtually extinct east of the Rocky Mountains for more than a century. Now a new study suggests that since their numbers have grown to around 30,000 in the Western states, young male cougars must roam ever farther to stake out unclaimed territory. In Missouri, officials confirmed 14 mountain lion sightings last year alone, more than over the previous 16 years. Cougars have recently been spotted in Oklahoma, Arkansas, and Illinois; one hit by a car in Connecticut in June 2011 had ambled east more than 1,500 miles from South Dakota, DNA tests showed. People have little to fear from cougars, researcher Michelle LaRue of the University of Minnesota tells Scientific American. Since mountain lions are “stalk-and-ambush predators,” she says, they tend to seek out heavily forested habitats where they can hide, both from their prey and from people. “If you were in the woods with a cougar and it saw you,” she says, odds are “it would run before you even knew it was there.’’