National Geographic 2016年第08期.pdf

AUGUST 2016 Panda Babies:Mission Critical August 28 at 8/7c on the Nat Geo WILD channelWith new gene-editing techniques,we can transform lifebut should we?OFFICIAL JOURNAL OF THE NATIONAL GEOGRAPHIC SOCIETY Oceanic whitetips slice through the water near the Bahamas Cat Island,believed to be one of the last havens for large numbers of the sharks.OFFICIAL JOURNAL OF THE NATIONAL GEOGRAPHIC SOCIETY126 Proof|Net Worth An artist makes scientiic portraits of birds.By Christy Ullrich Barcus Photographs by Todd ForsgrenOn the Cover DNA is in every living thing,and scientists have learned to edit it.“We now have a power over species of all kinds that we never thought possible,”says law professor Hank Greely.Art by Bose CollinsCorrections and Clarifications Go to 2016 vol.230 no.230 DNA RevolutionScientists now have a new tool to alter the DNA of living organisms.Should they use it?By Michael Specter Photographs by Greg Girard56 Science vs.MosquitoesMosquitoes spread some of the worlds most dangerous diseasesand we still dont know how to stop them.By Cynthia Gorney 60 Pandas Gone WildThe Chinese know how to breed giant pandas.To release them in the wild requires protecting habi-tat as well as the bears.By Jennifer S.Holland Photographs by Ami Vitale86 To the Last DropThe Ogallala aquifer feeds a multibillion-dollar farm industry.What happens when the water is gone?By Laura Parker Photographs by Randy OlsonThe Shipwreck SharkOnce the terror of the seas,oceanic whitetips have all but vanished.By Glenn Hodges Photographs by Brian Skerry112FROM THE EDITORPHOTO:FRANK MACK,FOR THE U.S.ARMY;COURTESY NATIONAL LIBRARY OF MEDICINESusan Goldberg,Editor in Chief Altering GenesA New War on MosquitoesNone of humankinds battles has proved more enduringor less successfulthan the war on mosquitoes.Around the world each year,millions of people die of diseases spread by the insect.Its a familiar list of stubborn plaguesmalaria,West Nile,dengue,yellow fever,forms of encephalitiswith some chilling recent additions.The mosquito-borne chikungunya virus has spread to parts of Africa,Europe,Asia,and as of 2013,the Americas.Its efects,while painful,pale in comparison with those of the Zika virus,which is careering through the Western Hemisphere and leaving tragically damaged babies in its wake.We have drained cesspools,warned of the dangers of standing water,and sprayed a river of pesticides.We have put up bed nets and window screens;we have educated and exhorted.And yet,by any fair measure,were losing this fight.The mosquito remains the most dangerous nonhuman animal on Earthand many scientists fear it may become even more prevalent and virulent with the rise in global temperatures and international travel.Our next weapon of choice is DNA.Scientists are working to neutralize the mosquito on its swampy home turf by altering its genetics.New gene-editing techniques,described in this months cover story,make it possible to tweak the mosquitos genome so it cant spread the malaria parasite.Another approach would genetically modify mosquitoes so that they bear sterile ofspring.And yet another would alter mosquitoes genes to prevent the birth of femalesthe ones that biteso the diseases will stop spreading and,in time,the insect will die out.Some may see these techniques as a revolutionary advance against infectious disease;others,as an unnerving case of scientists playing God.Like many breakthroughs,this one raises profound ethical questions.No matter how noxious a wild species is,can we aford to risk the consequences of altering its genetic code?Or can we aford not to,as malaria alone kills,on average,one child every two minutes in Africa?We invite you to read our cover story with these questions in mind.During World War II the U.S.military used cartoons to tell troops how to protect themselves from malaria.The National Geographic Society is a global non-proit membership organization com-mitted to exploring and protecting our planet.EDITOR IN CHIEF Susan GoldbergDEPUTY EDITOR IN CHIEF:Jamie Shreeve.MANAGING EDITOR:David Brindley.EXECUTIVE EDITOR DIGITAL:Dan Gilgoff.DIRECTOR OF PHOTOGRAPHY:Sarah Leen.EXECUTIVE EDITOR NEWS AND FEATURES:David Lindsey.CREATIVE DIRECTOR:Emmet SmithNEWS/FEATURES SHORT-FORM DIRECTOR:Patricia Edmonds.DEPUTY NEWS DIRECTOR:Gabe Bullard.EDITORS:Marla Cone,Christine DellAmore,Erika Engelhaupt,Peter Gwin,John Hoeffel,Victoria Jaggard,Robert Kunzig,Glenn Oeland,Oliver Payne.WRITERS:Jeremy Berlin,Eve Conant,Michael Greshko,Brian Clark Howard,Becky Little,Laura Parker,Kristin Romey,Rachel Hartigan Shea,Daniel Stone,Mark Strauss,Nina Strochlic,A.R.Williams,Catherine Zuckerman.CONTRIBUTING WRITERS:Robert Draper,Cynthia Gorney,David Quammen,Craig Welch.SPECIAL INVESTIGATIONS:Bryan Christy;Rachael Bale,Jani Actman.ADMINISTRATION:Natasha DalyPHOTOGRAPHY DEPUTY DIRECTORS:Whitney C.Johnson,Patrick Witty.YOUR SHOT DIRECTOR:Monica C.Corcoran.BUSINESS MANAGER:Jenny Trucano.SENIOR PHOTO EDITORS:Kathy Moran(Natural History),Kurt Mutchler(Scie