Новости науки и техники в "Scientific American"

FOOD FOR THOUGHT: DIET AND HUMAN EVOLUTION

We humans are strange primates. We walk on two legs, carry around enormous brains and have colonized every corner of the globe. Anthropologists and biologists have long sought to understand how our lineage came to differ so profoundly from the primate norm in these ways, and over the years all manner of hypotheses aimed at explaining each of these oddities have been put forth. But a growing body of evidence indicates that these miscellaneous quirks of humanity in fact have a common thread: they are largely the result of natural selection acting to maximize dietary quality and foraging efficiency. Changes in food availability over time, it seems, strongly influenced our hominid ancestors. Thus, in an evolutionary sense, we are very much what we ate.

SATELLITES TRACK NEAR-EARTH ASTEROID EXPLOSIONS

The recent Leonid meteor shower gave skygazers a chance to observe pieces of space debris meeting their demise as they collided with the earth's atmosphere at high speeds. Most of the streaks on display during the Leonid shower are just specks of cometary dust and hence pose little risk to observers on the ground. But explosions of much larger asteroids high in the atmosphere can cause considerable damage to our planet. A new study calculates just how likely such collisions are. The findings suggest that 10-megaton explosions from objects about 50 meters wide will occur about one third as often as previously believed.

BOOKSTORE: REINVENTING THE WHEEL by Jessica Helfand

"Twentieth-century volvelles - often referred to as 'wheel charts' - offer everything from inventory control to color calibration, mileage metering to verb conjugation. They anticipate animal breeding cycles and calculate radiation exposure, measure chocolate consumption and quantify bridge tips, chart bird calls, convert metrics, and calculate taxes." Starting as a collector of wheel charts, Helfand (a design critic and lecturer on graphic design at Yale University) came to recognize how old the concept is and to marvel at how many uses it has found. Focusing on the proliferation of these devices in the 20th century, she presents pictures and descriptions of nearly 100 of them. Her book is therefore visually intriguing. But it also ventures deep into the philosophy of the devices. Despite their wide range of content, Helfand writes, "these paper artifacts are somehow philosophically united in their unique approach to information design."

SUGAR GENES MAKE RICE CROPS STURDIER

The importance of rice as a crop - it currently feeds half the world's population - has fueled scientific attempts to improve yields of the plant. Earlier this year, two international teams published draft sequences of the genomes of two of the most abundant types of rice. Now researchers report having successfully produced a genetically modified form of rice that can survive drought, high salinity and temperature changes better than its traditional counterparts can.

MUD-LOVING MICROBES MAY AID IN MANUFACTURE OF NANOELECTRONICS

For their ongoing efforts to manufacture ever-smaller technological devices, scientists have recruited some suitably tiny workers: bacteria. Proteins produced by microbes living in extreme environments, it seems, can be used as building blocks for nanoelectronics. The technique could help researchers assemble electronics 10 to 100 times smaller than those available today.

MAKING DO

The National Museum of Namibia is a tiny institution. On paper, it reserves places for 12 natural scientists, but its staff is currently a third of that level. Its size, though, has not prevented it from making a major contribution to the natural sciences. The museum helped to turn up living exemplars of an unknown insect order, Mantophasmatodea, dubbed more familiarly "gladiators."

ASK THE EXPERTS: DOES THE APPENDIX SERVE A PURPOSE IN ANY ANIMAL?

Julie Pomerantz, wildlife veterinarian and program officer for the Wildlife Trust's North American Conservation Medicine Initiative, explains.