Even better than a self-cleaning oven, we benefit from a self-cleaning brain

Q. History buffs, have you ever wanted to visit some of the camps that Merriweather Lewis and William Clark set up during their two-year round trip from Illinois to the Pacific coast? What unlikely source might help you ascertain that these locations are accurate? A. Although the explorers produced a welldeveloped series of maps, they are not the answer, since mapmaking of the time lacked today’s tools — GPS technology, aerial cameras, and the like, says Dan Lewis on his “Now I Know” website. No, the key is that we know where the team set up their latrines. Since along the way they needed something to fight off infection, they used calomel, a laxative that killed bacteria but also contained a high level of toxic mercury.

Archaeologists attempting to determine the exact location of a campsite can test a nearby latrine for mercury, “which shouldn’t appear in nature otherwise… and stays behind effectively forever.” One such site — Travelers’ Rest State Park in Montana — has been identified “as definitely a Lewis and Clark (rest) stop based on the mercury in the latrines. But more, hopefully, will be identified over the coming years.” Q. How might a blind person rehearse the layout of a place in a new city before traveling there? A. By utilizing Microsoft’s ‘canetroller,’ “a walking cane that simulates the feeling of real objects with vibrations” and that includes auditory feedback as well, reports “New Scientist” magazine. With the digital world thus opened up to the blind, one woman standing in an empty 22-square-meter room said she felt like she was “hitting up against” the virtual room’s walls. A man said he could “feel textured surfaces.” Adds Microsoft’s Meredith Morris: “It could even be used to practice navigating in the snow in advance of a storm ...” Q. Male crickets woo by vigorously rubbing their ridged wings together to call females, but over time up to 95% of male ocean crickets on several Hawaiian islands have evolved flat wings, “leaving them mute.” Is there an upside to this unwelcome development? A. The downside, of course, is that this muteness hurts their chances of mating, reports “New Scientist” magazine. But it also protects them from a parasite that “homes in on a male’s song and sprays the cricket with eggs. The larvae then eat the cricket.”

Despite their silence, these males still rub their wings together, says Nathan Bailey at the University of St. Andrews, UK (“Biology Letters”). It seems that while “some animals have vestigial organs with no function, these crickets have vestigial behavior.” Q. You’ve heard about “self-cleaning ovens” and may even own one. But all of us “own” our own “self-cleaning brains.” Explain, please. A. The brain is bathed in clear liquid called cerebrospinal fluid (CSF) that carries nutrients in and waste products out, reports “How It Works: Book of Amazing Science.” A barrier shielding the brain is made and maintained by astrocytes, star-shaped cells hugging the blood vessels and controlling this in-out process. At night, the astrocytes relax their grip and the channels around the blood vessels widen, allowing CSF to sweep through the area, carrying waste products toward vessels where they can be removed via the bloodstream. Since brain cells are constantly creating waste products, without this mechanism waste could build up, causing brain damage.