AEXPLOREPlanetEarthEachdayabout5,000acresoffarmlandworldwidebecometoosaltytosustainSalt ofcropsprofitably.Alllandisnaturallyvulnerabletoeithersodiumorsodiumchloride(or both) that accumulates in soil. Poor drainage can make it linger. When salt buildsthe Earthuparoundroots,plantsworkhardertogrow.Inall,astudyshows,morethan153millionacresofirrigatedland-aboutthesizeofFrance-havebecomeunfarmableFarmerswon'tbetheonestofixtheproblem,though,accordingtoManzoorQadir,a soil and irrigation specialistat United Nations University.Instead,hesaysgovernments need to mandate field drainage on a large scale. A more immediatesolution may come from plants themselves. Research indicates that food cropssuch as wheat and rice could be genetically engineered to resemble plants likeseaweed, which evolved salt tolerance long ago.Daniel StoneFarmers in Ban-gladesh's Satkhiraregion have con-verted saline ricefields into pondsASIANORTHEUROPE(above) to raiseAMERICAshellfish.On nearly everycontinent, salt-affected soilhasmadeareasAFRICABANGLADESHEQUATORdifficult to farm.SOUTHAMERICASoil significantlyaffected by saltNaturallyoccurringAUSTRALIA Human-inducedPHOTO: JONAS BENDEKSEN, MAGNUM PHOTOS2,0000 miMAP:JEROMEN.COOKSON.NGMSTAF0.km2.000SOURCES:EDDYDEPAUW:FAO:CENTERSCALE AT THE EQUATORFORENVIRONMENTALSYSTEMSRESEARCH
BANGLADESH ASIA NORTH AMERICA EUROPE AUSTRALIA SOUTH AMERICA AFRICA ASIA AUSTRALIA EQUATOR PHOTO: JONAS BENDIKSEN, MAGNUM PHOTOS MAP: JEROME N. COOKSON, NGM STAFF SOURCES: EDDY DE PAUW; FAO; CENTER FOR ENVIRONMENTAL SYSTEMS RESEARCH Planet Earth EXPLORE Each day about 5,000 acres of farmland worldwide become too salty to sustain crops profitably. All land is naturally vulnerable to either sodium or sodium chloride (or both) that accumulates in soil. Poor drainage can make it linger. When salt builds up around roots, plants work harder to grow. In all, a study shows, more than 153 million acres of irrigated land—about the size of France—have become unfarmable. Farmers won’t be the ones to fix the problem, though, according to Manzoor Qadir, a soil and irrigation specialist at United Nations University. Instead, he says, governments need to mandate field drainage on a large scale. A more immediate solution may come from plants themselves. Research indicates that food crops such as wheat and rice could be genetically engineered to resemble plants like seaweed, which evolved salt tolerance long ago. —Daniel Stone Salt of the Earth Farmers in Bangladesh’s Satkhira region have converted saline rice fields into ponds (above) to raise shellfish. On nearly every continent, saltaffected soil has made areas difficult to farm. 0 mi 2,000 0 km 2,000 SCALE AT THE EQUATOR Naturally occurring Soil significantly affected by salt Human-induced
Started my Camry.Wanted tacos for lunch.Crossed down into BajaJoineda soccergame.Lostmypassporttoaseagull.Hitched a rideon a cargo shipGot boarded by pirates.Freed some livestock.Retook the ship.They were really good tacos.THEB0L02015CAMRYDNEBOLDCHOICELEADSTO ANOTHERThe2015Camry.Yourfirstboldchoice.Let'stoyota.com/camryGoPlacesTOYOTAPrototype shown withoptions.Production model willvary.@2015ToyotaMotcSales,U.S.A.,Inc
Prototype shown with options. Production model will vary. ©2015 Toyota Motor Sales, U.S.A., Inc. The 2015 Camry. Your first bold choice. toyota.com/camry Started my Camry. Wanted tacos for lunch. Crossed down into Baja. Joined a soccer game. Lost my passport to a seagull. Hitched a ride on a cargo ship. Got boarded by pirates. Freed some livestock. Retook the ship. They were really good tacos. ONE BOLD CHOICE LEADS TO ANOTHER
EXPLOREScienceHot PotatoesThis year a genetically engineered potato may hit agrocery store near you. Using a technique called RNAinterference (RNAi), scientists have silenced genes thatleadpotatoes tobruiseand tobrown whenexposedtoair-the two characteristics that land roughly 30percentofharvestedpotatoes inthetrash.Thesenewspudsalsocontainupto70percentlessofanaminoacidthattransforms intoacancer-causingcompoundathightemperatures.Asecondversionwillberesistanttolateblight,thediseasethatcausedthelrishpotatofamine.TheJ.R.SimplotCompanythatcreatedthepotatocalls it Innatesinceitdoesn'tcontaingenes fromotherspecies.Even so,McDonald'swon'tbe serving it.RNAiis a"veryroutineprocedure inresearch,"says KentBradford,abiologistattheUniversityofCalifornia,Davis,but "the marketing situation for genetically engineeredproducts is toxic."-Rachel Hartigan SheaOne day after slicing,ordinary potatoeshadtumedbrown;the geneticallyengineered potatoesremained pale.PHOTO:MAFNGUSTA
PHOTO: MARK THIESSEN, NGM STAFF Science EXPLORE This year a genetically engineered potato may hit a grocery store near you. Using a technique called RNA interference (RNAi), scientists have silenced genes that lead potatoes to bruise and to brown when exposed to air—the two characteristics that land roughly 30 percent of harvested potatoes in the trash. These new spuds also contain up to 70 percent less of an amino acid that transforms into a cancer- causing compound at high temperatures. A second version will be resistant to late blight, the disease that caused the Irish potato famine. The J. R. Simplot Company that created the potato calls it Innate since it doesn’t contain genes from other species. Even so, McDonald’s won’t be serving it. RNAi is a “very routine procedure in research,” says Kent Bradford, a biologist at the University of California, Davis, but “the marketing situation for genetically engineered products is toxic.” —Rachel Hartigan Shea Hot Potatoes One day after slicing, ordinary potatoes had turned brown; the genetically engineered potatoes remained pale
Leave abeautifullegacyBy including National Geographic in your willtrust,retirementaccount,orlife insurancepolicy,youcanpassonyourloveofexploration,science,andconservationtofuturegenerationsYou'll be supporting criticalprojectssuchasthe Big Cats Initiative,which is working toprotecttheseendangeredcreaturesandtheirhabitatsIt'sapowerfulgiftthatwillmakeapowerfuldifferenceNATIONAIGEOGRAPHICCOPYRIGHT2015NATIONALGEOGRAPHICSOCIETYPHOTO CREDIT,BEVERLY JOUBERTNameI haveincluded National Geographicin mywill,trust, or beneficiaryAddressdesignation.PleasesendmeinformationaboutPhoneeasy ways to leave a legacy ofEmailexploration and conservation.Iwouldliketospeakto someoneaboutMailtoNational Geographic Societymakingagift.Pleasecallme.Office of Planned Giving114517thStreetN.W.Youmayalso contact National GeographicatWashington,D.C.20036-4688[800)226-4438,plannedgiftinfo@ngs.org,orwww.ngs.gift-planning.org/GIFTbequestThe National Geographic Society is a 501[c][3] organization. Our federal tax ID number is 53-0193519.15PGFC05BL
COPYRIGHT © 2015 NATIONAL GEOGRAPHIC SOCIETY By including National Geographic in your will, trust, retirement account, or life insurance policy, you can pass on your love of exploration, science, and conservation to future generations. You’ll be supporting critical projects such as the Big Cats Initiative, which is working to protect these endangered creatures and their habitats. It’s a powerful gift that will make a powerful difference. Leave a beautiful legacy Name _ Address _ _ Phone _ Email _ Mail to National Geographic Society Offi ce of Planned Giving 1145 17th Street N.W. Washington, D.C. 20036-4688 Please send me information about easy ways to leave a legacy of exploration and conservation. I have included National Geographic in my will, trust, or benefi ciary designation. I would like to speak to someone about making a gift. Please call me. You may also contact National Geographic at (800) 226-4438, plannedgiftinfo@ngs.org, or www.ngs.gift-planning.org/GIFTbequest The National Geographic Society is a 501(c)(3) organization. Our federal tax ID number is 53-0193519. 15PGFC05BL PHOTO CREDIT, BEVERLY JOUBERT
BasicInstinctsA genteel disquisition on love and lust in the animal kingdomA Girl's Gotta EatFood. Sex. They're primal preoccupationsfor humans and our closerelatives, chimpanzees.For years Homo sapiens scientists have watchedHABITAT/RANGEthoseappetitesplayoutamongPantroglodytes withmixedresultsForestsandsavannawoodlandsin21AfricannationsFemalechimps averagefivetosixyearsbetweenbirths,oneofthelongestintervalsofanymammalToraisetheoddsofreproducing,aCONSERVATIONSTATUSfemale will mate"with most or all ofthe males sheknows,"says prima-EndangeredtologistMelissaEmeryThompson,whileamalewillcompeteorfightOTHERFACTSwithotherwould-besires.SomestudiesreportcasesofmalechimpsFemalechimpsmatepromis-tryingtosweetenthedeal:sharinggametheykilled,orcropstheyfilchedcuouslysothatmanymaleswithfemalesthatmatedwiththem.Ina2007WestAfricanchimpstudy,think they might be a baby'safemaleconsortedmorefrequentlywithamalethatgaveherstolenfatherthat discouragesinfanticide.papayas, leading researcher Kimberley Hockings to suggest the malewastrading"forbiddenfruit"for"othercurrencies."Manystudiesdon'tsupportthefood-for-sextheory,EmeryThompsonsays:"Peopletendtohangontotheideabecausetheyfindittitillating.AfemalechimpWhat her chimpresearch has found, she says, is a different food-sexwill mate“withissue. With sex-seeking males surrounding them, females areless abletomostorall oftheforage andfeed.Thatdrives down fertility and their abilityto replenishmalessheknows."their endangered species.-Patricia Edmonds
A genteel disquisition on love and lust in the animal kingdom Basic Instincts PHOTO: VINCENT J. MUSI, NATIONAL GEOGRAPHIC CREATIVE Food. Sex. They’re primal preoccupations for humans and our close relatives, chimpanzees. For years Homo sapiens scientists have watched those appetites play out among Pan troglodytes with mixed results. Female chimps average five to six years between births, one of the longest intervals of any mammal. To raise the odds of reproducing, a female will mate “with most or all of the males she knows,” says primatologist Melissa Emery Thompson, while a male will compete or fight with other would-be sires. Some studies report cases of male chimps trying to sweeten the deal: sharing game they killed, or crops they filched, with females that mated with them. In a 2007 West African chimp study, a female consorted more frequently with a male that gave her stolen papayas, leading researcher Kimberley Hockings to suggest the male was trading “forbidden fruit” for “other currencies.” Many studies don’t support the food-for-sex theory, Emery Thompson says: “People tend to hang on to the idea because they find it titillating.” What her chimp research has found, she says, is a different food-sex issue. With sex-seeking males surrounding them, females are less able to forage and feed. That drives down fertility and their ability to replenish their endangered species. —Patricia Edmonds HABITAT/RANGE Forests and savanna woodlands in 21 African nations CONSERVATION STATUS Endangered OTHER FACTS Female chimps mate promiscuously so that many males think they might be a baby’s father; that discourages infanticide. A female chimp will mate “with most or all of the males she knows.” A Girl’s Gotta Eat