CINXE.COM

<!DOCTYPE html><html lang="en-US"><head><title>Just a moment...</title><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><meta http-equiv="X-UA-Compatible" content="IE=Edge"><meta name="robots" content="noindex,nofollow"><meta name="viewport" content="width=device-width,initial-scale=1"><style>*{box-sizing:border-box;margin:0;padding:0}html{line-height:1.15;-webkit-text-size-adjust:100%;color:#313131;font-family:system-ui,-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,Helvetica Neue,Arial,Noto Sans,sans-serif,Apple Color Emoji,Segoe UI Emoji,Segoe UI Symbol,Noto Color Emoji}body{display:flex;flex-direction:column;height:100vh;min-height:100vh}.main-content{margin:8rem auto;max-width:60rem;padding-left:1.5rem}@media (width <= 720px){.main-content{margin-top:4rem}}.h2{font-size:1.5rem;font-weight:500;line-height:2.25rem}@media (width <= 720px){.h2{font-size:1.25rem;line-height:1.5rem}}#challenge-error-text{background-image:url(data:image/svg+xml;base64,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);background-repeat:no-repeat;background-size:contain;padding-left:34px}@media (prefers-color-scheme:dark){body{background-color:#222;color:#d9d9d9}}</style><meta http-equiv="refresh" content="390"></head><body class="no-js"><div class="main-wrapper" role="main"><div class="main-content"><noscript><div class="h2"><span id="challenge-error-text">Enable JavaScript and cookies to continue</span></div></noscript></div></div><script>(function(){window._cf_chl_opt={cvId: '3',cZone: "www.science.org",cType: 'managed',cRay: '8e988c837e6140bb',cH: 'KNELQ7B3LaaUpEbQ0wXR7AO_Wqb7LbKwZZHhRGguvQI-1732777938-1.2.1.1-AJgWQbTvAC8cia6HqtME_ZEBAIMsVo457GFee9jLDiNPe68UpP2KyDAH5a2XvOQg',cUPMDTk: "\/doi\/10.1126\/science.1108872?__cf_chl_tk=eH0MeRTRTR4YG3t7YnlFRPCclRjj5CpCSrSyJFEuCjI-1732777938-1.0.1.1-Oz..crPZE6dYgP6RqLImJC58NjR16AoVmceW1k4.ghU",cFPWv: 'b',cITimeS: '1732777938',cTTimeMs: '1000',cMTimeMs: '390000',cTplC: 0,cTplV: 5,cTplB: 'cf',cK: "",fa: "\/doi\/10.1126\/science.1108872?__cf_chl_f_tk=eH0MeRTRTR4YG3t7YnlFRPCclRjj5CpCSrSyJFEuCjI-1732777938-1.0.1.1-Oz..crPZE6dYgP6RqLImJC58NjR16AoVmceW1k4.ghU",md: "0icRAw1uoT25FmiCv0O4Fg2u.niRanigV7hnv.EkaOQ-1732777938-1.2.1.1-wb6XBwVMvRw6DytpIJQp7dp4we_5Z37JUXRITOXEXOYRXx51Jwcpekm.e2KYPHAdLlQdYlQn_zKrd6GOimTHb7pPMm1Y8678lfZoIb_BJtHdhOhXSFMrEhPBZjiThvvHzQT1skIt8O5531Mp3zSzT3ZtxtQXf6K5MppQggfrtxe6jbUk.62J8Z4dIaVDMGRqyGG0Bbc4mUjP1p090p1BW5O3jApEEfkTKT6VMP9qJPcuCRKGtegX30MxgBn_0m.WqrZ3RnTdjuZyfBinUDGZbagE1ua6YdBB.0yOXemIu9lNOvAxbBeE5O1BKFmpsK5h_MvtCHKQ6jNpwQKkJjGwnQMZbamseAXxewfrR6I2UvnCdWj0Tsy3rh1fshi1kvWoVO3s5pd9vcPasrZrDVEEBz80ZwUQtdfLmrezHOgbEsu8RsXkIOwQEd6hod.sx6p443pN2ubfuzKLc88Mn7gKA7DeEINC3jCaa9IfWyHR8iR4dZY5YMUk7aLkAUnQGr5zvxQAIr_52udkmq70WtcUEXCENZOoGsrjJ_nBJp2nt5fv0c0YGCcM3Pb3.Zv3nL22D3k1tj5mEESJa_Uydoix5s9IcpjCuirso1grqWrVG615jqJgnCxkohAMdhfEUDnDL2bVq_cNbAuRoGzm5rGVweIP_3NDiBBfENZcOEYPPEKWFhI.Q2h869dRp40LVAx1uTkbmqwBF9okkVI1gMh0didrzexL1JHuGUbdBuTBhCOd7rM0ElKr_x9LJr27wmAwP167A9Ps_t68yo1MUJi7xHkksKcL87k1pUWwiN4HsBk3T3K0yok7pmNaCG0vGRnDv3mntwVdkQ4Ud0GBeYS2rWjZg47cwCg_W1_UBbN1KvgW_O6vciX.rqmk8oXNAgNQj8NWrwFGKve6WHveolcozFqlG7OWEyQAf_uISZEbZX6jGijn.0afkt9xKWRT1c7Pxb1EeML8G8X_Tm8tVQupJ1Wn2uJq2LlApEO.ju2bv_oA2RpaTRj77hlgYlUEE28kVM08xjmvf6bTO.QaWzBPZZiWXR8UG5l_xrHL8HSY37lDaJ5EoSg_lUOfK8D8BVnHgM3g3_D9diYxN9bPVkPk3CzJtvDCObAyr9lOxpGs9TBFeH_AMTGXBIuQmBS9VLs1SCeo2hmnwtNWAGjD64OGwjgx4ZIVan9enaLOJVYg.zt3EsZmRlLsWLuXZdcGMbXxEFrHgux7Os6VGyvzpPiBSYF7vQNdWq5bv2dsgILgh9HRxEo4FBJ1IwA87bg9smL9VOMzVqf5PUDAyXiGfekLswS_VClSDsiUhTnJa4LeT9ZgfkUlyWVU3nNPlWB0yobsNu9ZZV3EMGkd8CJtSkaoPQTeIK.MprwLNrhdTEScco1t0RhiYim3Bs7dSTqQ2_e7xnP3_irqsjVU1XgtojpvEfyn7Yzomaltbx9sS.34VyQo7GtEh4Pufp554aZe1X9e_TtrfZiWrT.o6mhHmUOwSyGy3eT5MfcQw6VNT454CXqkZei_OYrTvPsOcGWV_uApAgFMwhNHDxAsELBXbQAB_fnNw.UzfufqPHvOjtwvEqpPrHynG1o2moFleCx4ZowlORMOONyPgDMPx7JGsYh.olbKTigMJSUoDCdsXgg7CP2Ke_A__CEhQANq2Zwzabo9wf7bH4W3kt_VeHmy412O74za6mw1mxXRr_ouVdtFQv_OTqhVTwTKm4_tyym_EMEysvJP23UrCpF4t5mAfUigcfQtkILmZSapW4Sf.ngmH5ssNnaIE6_2eZ9vm4DrNKB4BBzfskEPMG5sRmwSxg4H6LWQHofajZaxJpBS5CZ3PXldaOTTq826cQ976r8VHXk6XXpFZTUJxz8RBElnlyPcaE9G4slPDQwLnX5Bqn5q0_NQx8pSPNWzioZBEfb3G.rng5qpj_rdRw0EIxOwOV_KvUuCu7shpv3nqM769lJsxQRk0N6X7CG41bWN6ieZJOa.aHGRumAVyDsrtfdIfV7YxkejXDEkCDmEZbQtWNmWj4gJFmzbzDOzU0ybslhSvcRkg3sP1oYwpdQn8l4Ex28JOjvoj8q06pdh364ag1U2Na9tsf4S3sYc8fGOVMKfF15Cp4VFAD4IOu8PMwDHfLIITcxIP1ajMzXdynN2cTfduMVYgSk8JSVL.zUHLi4R1yPQt3muuU3nG995Iks1r_V85Qwb75fQqNv0hKJrvWYV7lqCQQ5JdXYRFSKsR0VdnoXo.pne7x7IjdhaM5M59qcObjN5yMYZPRhDJDDigsBDMtQpNjIVV_xYzoJ8dqKSxeqtOZ275nIfahg17l.d5RDkjcDekkUJmzRxRO32V1r6DSDomNdH3wMxAB55bdjHLxqJ8ToHASD9pHCXXWeUWIM_wSOacdJTvbgTJGnmlDO1tL5nPjNdwRlufgl70fwEQf.xiazOIyR9PcXrszDFQcWNjs6UL4zs0d0OPIFgPyjeqLHE6wAhZipEV4tUxjkr_CayGoTHTHFlnAf.ky1QsWrpcPdyjW90gjlbzRh8dW4wRq7v2ZFPpWKEYhNGxPg06bbxjWss9QOZm7DSc6C7Lold.i4_BtWrKBl2.4cB62B1lPZTXIavHeYabIWKzQslF1EVhoehu.AAVWTB8A23LEw2lb8W4S5pND6vgezxoftIran7EXBUVDa_zbZpeFR2Z7sL8sg7FrvdzCU8FpS9sFUcFVvkSee7rgvsvnDiJCohE2CHMyN.eBNvDFXHlWTLM7KOD5SVKM.wmY32seM.byw9VDR9qSUwSpNMWmI3MqiqLfnwGkQ7GeQIEZIoYUQ7MfBswS.QZGFy_1FbyZk3EfjWzpf9Pr5FmynI.Hya7m9DhcvN9pgD14nu_YldQPbvEjGO0j7H8W_OfGhMlTPbnVwTj4xXupZEKYl0ipjh6GHOlw.pCwKPb9ieMQ8tGbhsW4DCYw8tHWtxV6bfnyOsb3oG5pFVk2Q.sF61okLup4.e0lA",mdrd: "LmmnEZ4mS83RqsJHzjCX85i7G40VlBr2k0QrSjHUu5M-1732777938-1.2.1.1-0auMJTai93s5u7LMXzQEPVCmPw51uF0MdQqss10ju4uzYyyg.tzWvaPbL742xSSkZ3vJXFT5m39cWZKjoQPkkGoHNaoAHJPzfOggacZIxQ9Rqk_MO0EyY4MqC1EohBU_6wi0.dnWazt0EoKYjCwXSCkc_8gGNU9CPRvgOTQCWRUv4Gadw.M2NXXfk14q9RrmnXgOme8oB0ZwMl5.ghGU9rZb8sbWAPQlEyk5AXg7lPIzgKz9WMQnFDmu9NZv26x37aHB2l5fqj0Om0Pkptki13W0G391CCcLPExuZEn13u4yYMbjet8MuSLh.V6NCvaKhcfK.aechro0E4.m_eZllO8IBZf1OzHV2ZDwY7EpEtY7yhyG0aTsLBNXC67_4bxhOKTGG8VPo2CHp8G7CvgdMyUWvtHDdjh51dY2QWlzzE_NZM49ZNfLj856SpqpY0MVs.tmD72_fta7NHtMaO.aghDLV71.cnWSp6ga00uoBF4gfPBbREoleE1kuQ95nTH3HGfgQ.x1TQHVvuunHobA6U6aqe_hXNyrq8xvKKb96dfx_aa1ljWHiUb0VtloU3iQTy_tnC4Sf.tCfke7oWyCbLBbM1nFeCuRKHTg534O5bDU4xS0R6eFSoOTukpv9HYevSYBPi120E9_4pGKehWCQExXw9q1Sf.Y5HB6VpEV77nwCa3PhtgolktBH6g.4mCPvkEVETOM0DyGgZPOvqcAaBquF.ftqf8vkM1KfjMukAXIguV6Fy2X8B8kH4laz3GkgkBFcO.i0glzztwhMDu2goRQiK4EIiQWEmmvyUMBGlllgYJeBgO9iPw_0KTEUYFumIwOGOiXU6TROwkzo8bK4R8j2OpaIW9JImHqRJLj4qAGxLze9V0xzmc1MeXHqxp7WxD0lQnzAByqsH07hv0ZaJ3EaILqAgZ7etW2FIRgSGvq7EnUzPTCiPe2PN4mHISojK2wsYOp3VP4AU.u9_NFieQc8tGAT9CiLPD._UoDntzFQuIEMfUq8jeYOd1SxAzjDoGysAfbjMY7caL2rFuWjt0PfwFamoohzZzzZ2rkSNaIoCoNUjvdtgGRzEA9cKsGAjDAm0F0XVmF1gQzvTthfy2khoopRCQhYvZjPtR7LMzMVBv_ZMT8RVsgyFbNyaputgeF.E5Af9vrpWCWAhYViFGXsGsPsw79RW8MbXPepzf.pMtjyHRDQZ0gTs2vYFuhTZx4Mgmf9aDOGok1yJVEmF6GZfV5QB6n4ZM.17cq5a.0PEW4oxW9BoSlMqmgcWR7CCXnsALRAtb19rcu3lDmWYPyuNpbx.iSG8DysLhrzo5ylM3rbtjrY7SfJs.S2u9vPfmtQpeSj3g2QlymMNDaFuWJLjVC3_6XVuMThKHxtbcjzittfvgZtEprvDtS6Id59YnhF1hxw_DneyWGRANzh_R5Z3KYgXPojBe5fT8QNMcdX8z3U1Dyqc6u_bHVhUvZYvhAQ4UmxOTsVwc.zw9Ntl9JXxang5rreB1WK50bwKzjCzSjRfdsx6XWhGNPN9Ze7nDzKqsqrCRz93WBZXC.c59H_964Q7G0Hd98c.IWHBAN_e5KthzkdJanjYAnHoR4OWQlvyhQ316DcLaBj5jagxoAsYnplUtWOyRY91eXS8McZLSYPYgddv6DTT6rROwJKamuBh0ye.vm93FGGMZ9wHYTFRC603b6d8oOXWy1WMNj7deOQLzmFaOQQOUdI2_w0occvJaG.helwnIJljSr_T3jMs7bpDhnprsgHjX4U45CGp9e0KBu9iww12LIobMIEFutM0bVhiJ7s1QQqUe_TWfjq64FoOVGiFp.PuFNn0i68P4ADtRdMKPwGPiKlyS.1W77MNziEFsPADo7RO2W9BBRIvhWySyBb67yU8E9aDEi2EUOKIRkZljzWVQb_VIfN6K3RbMUbWMGbeH4cn0Adzc4wH_QOWldKXuyQAxG_4ijYh2EHmos.45KWQxOmNm."};var cpo = document.createElement('script');cpo.src = '/cdn-cgi/challenge-platform/h/b/orchestrate/chl_page/v1?ray=8e988c837e6140bb';window._cf_chl_opt.cOgUHash = location.hash === '' && location.href.indexOf('#') !== -1 ? '#' : location.hash;window._cf_chl_opt.cOgUQuery = location.search === '' && location.href.slice(0, location.href.length - window._cf_chl_opt.cOgUHash.length).indexOf('?') !== -1 ? '?' : location.search;if (window.history && window.history.replaceState) {var ogU = location.pathname + window._cf_chl_opt.cOgUQuery + window._cf_chl_opt.cOgUHash;history.replaceState(null, null, "\/doi\/10.1126\/science.1108872?__cf_chl_rt_tk=eH0MeRTRTR4YG3t7YnlFRPCclRjj5CpCSrSyJFEuCjI-1732777938-1.0.1.1-Oz..crPZE6dYgP6RqLImJC58NjR16AoVmceW1k4.ghU" + window._cf_chl_opt.cOgUHash);cpo.onload = function() {history.replaceState(null, null, ogU);}}document.getElementsByTagName('head')[0].appendChild(cpo);}());</script></body></html>