collidin Galaxi STEP INTO A SPIDER'S WORLD! SEE THE REAL LIVES OF SPIDERS IN A FASCINATING LIVE EXHIBIT y><\: SEPTEMBER 23 - NOVEMBER 4, 2007 / \ h^\ Join us as we welcome back the Spider Pavilion 'Natural where you will see amazing orb weavers create beautiful webs, catch their meals and interact -History with each other just as they do in the wild. luseum For more information and a complete list of of Los Angeles County activities including our famous flashlight tours visit www.nhm.org/spidei-pavilion. 900 Exposition Blvd., Los Angeles, CA 90007 '2i3-763-DINO www.nhm.org Admission to the Spider Pavilion is not included with regular Museum admission. Prices are: Adults $3.00 I Students and Seniors $2.00 I Children 5-12 $1.00 I Members are FREE. SEPTEMBER 2007 VOLUME 116 NUMBER 7 FEATURES DEPARTMENTS 2 THE NATURAL MOMENT Over Easy Photograph by Peter Blackwell 6 UP FRONT Editors Notebook 8 CONTRIBUTORS 10 LETTERS 12 SAMPLINGS Ne\\'s from Nature 32 THIS LAND 18 DARK MATTER Rendezvous at Red Rock Rohcrr H. Mohlciihrock Most of the stuff of the itnii'erse is invisible and rarely interacts 34 REVIEW with "ordinary" matter Experimenters Literary' Gould Laurence A. Marschall arc racing to answer the question, Wliat is it made of? 35 nature.net DONALD GOLDSMITH That Gnawing Feeling Robert Anderson COVER STORY 38 OUT THERE Surprise Package Charles Liu 44 AT THE MUSEUM 48 THE SKY IN SEPTEMBER Joe Rao ON THE COVER". Computer simulation 24 ALTRUISM AMONG ot collision between our Milky Way AMOEBAS galaxy (lower left) and Andromeda galaxy (center). biUions of years in How can evolution explain the selj- the ftiture (image by John J. Dubinski) sacrificing behavior of nonhumai] whose geties arc "selfish"? organisms PICTURE CREDITS: Page 8 JOAN E. STRASSMANN AND I 'bjf our Web site at DAVID C. QUELLER www.naturalhistorymag.com ^ M '^K. * fi: ? ^ \) V f. > / , t \ Love Potion #7? THE NATURAL MOMENT THeiSIew Science of Love with a little vyizaImry uiroyjn ul "* See preceding two pages many omance is all about Not mothers chemistry and these : would inter- ^ seven brilliant stones rupt an after- can add just the right magical noon nap and fire raise the temperature of to leave behind your secret potion. In today's most -.i their six-week- important design called the "River of old youngsters Love", this pendant of 2 carats t.w. of to seek out a graduated DiamondAura stones is the thundering herd of wildebeests. But for perfect blend of science and sorcery. • this lioness in Kenya's Masai Our Gemologists have broken the code" , Mara National Reserve late to create an impeccable stone with one September afternoon, such j§g even more fire and better clarity scintillating a stampede was worth it. Peter than mined diamonds. Of course, the 5 DiamondAura 18k gold Blackwell, who had been pho- Diamond4ura stones are hard enough tographing the dozing feline over sterling silver to cut glass and they are so clear and \ family, trailed behind her. stud earrings white that they rival a "D Flawless" Only a few hundred feet diamond in terms of color and clarity. away from her cubs, the lioness In the laboratory, we have found a way to Read details below. came across an ostrich nest in the dirt, and promptly caused match the brilliance and stunning reflective another female to ditch the qualities of a diamond by using science young in her care. The ostrich and thus we avoid the outrageous price. on incubation duty wasn't The 4 Cs. Our DiamondAura jewelry prepared to fight for the nests' , retains every important specification: eggs, for several reasons. Only ostrich in ten actually color, clarity, cut, and carat weight. ( one egg In purely scientific measurement hatches—even in the absence of marauders. The few chicks that terms, the fire is actually superior to that of a diamond. Fire is the do emerge stand a good chance dispersion of white light into a rainbow of color. Our team of cutters of being pilfered by other os- and polishers artistically performs the symmetrically brilliant, trich parents seeking to enlarge 58-facet cut to maximize the light reflection and refraction. their broods. Finally, some of The "River of Love" is for that love of a lifetime. The 2 carat the eggs probably didn't even belong to the runaway ostrich: DiamondAura "River of Love" 7 stone necklace is mounted in 18k gold typically, several females lay fused over sterling silver for only $129.00! Just to make the magic more their eggs in a single nest, £fa tempting, we will include the .86 total carat weight DiamondAura stud scraped out by a male. earrings for fREJE! If you are not thrilled with the briUiant romance of So with nothing but the eggs' the DiamondAurit4^-"River of Love" necklace, return it within 30 days for size (six by five inches) and thickness (one-eighth inch) to a refund of your p^ehose price and keep the stud earrings as our gift. slow her down, the lioness pic- Blackwell watched Not Available in S nicked away. her gorge on "many good eggs, Gci/I now to lake culrcinlci}>L' of tB/f limited offer. but also several bad eggs, which UiaiaondAura "River of Love" necklace exploded when she clamped 2 ctL t.w, DiamondAura 18" goldpendant with 7 stones • $129 + S&H down on them, leaving a rather disgusting smell." Unfazed and .86 ct. i.yv: DiamondAura gold stud eanings tULL when ordering the energized, the lioness resumed »f Love" necklace - a $69.95 value! the wildebeest chase and made a Call to order toll-free, 24 hours i\ day. days ja week. 7 W -^ >% -4 1 y% -M StAucr successful kill. 888-201-7059 —Erin Espelie 14101 Southcross i:)rivc W., Ocpr. ROL201-02 otional Code ROL20I-02 BurrLsvillc, Minnesota 55.3.^7 NATURAL HISTORY September 2007 bepfipp this code when you call. www.stauer.com rodijcing the Acoustic Wave® music system II. Our best one-piece music system. When we introduced the original Acoustic Wave® music system, Sound & Vision said it deHvered "possibly the best-reproduced sound many people have ever heard." And the Oregonian reported it had "changed the way many Americans listen to music." Today, the improved Acoustic Wave® music system II builds on our more than 40 years of industry-leading innovation to deliver even better sound. 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