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: '9135f02d3a90fce2',cH: '4Yub0iaIp0UDcy63CZm3g6zq0CvPZtVtM1XK_xNMPno-1739796994-1.2.1.1-.2sIuDMijn5b_Xl9SRNRVDteg8FaFMLhisU0mY9kL_4B4wSCyh450XXtdC2_UXlL',cUPMDTk: "\/doi\/10.1126\/science.371.6531.766?__cf_chl_tk=tYG8AIPZlpiTeoGfqV9hF7xwBLGiFCi2PB1a9oak1UA-1739796994-1.0.1.1-0XnQAWlh4x.nj8bUQNGqlkRfkBc32OdLHhr8ryI0Hoc",cFPWv: 'b',cITimeS: '1739796994',cTTimeMs: '1000',cMTimeMs: '390000',cTplC: 0,cTplV: 5,cTplB: 'cf',cK: "",fa: "\/doi\/10.1126\/science.371.6531.766?__cf_chl_f_tk=tYG8AIPZlpiTeoGfqV9hF7xwBLGiFCi2PB1a9oak1UA-1739796994-1.0.1.1-0XnQAWlh4x.nj8bUQNGqlkRfkBc32OdLHhr8ryI0Hoc",md: "Bzw.Y_GPEGZm3RcgmwfDRH3z6fXPGjsCv2NtsUy1fJE-1739796994-1.2.1.1-07tw7jluhN0kET7y2QCqojclNcM6h9gsJ48n8rChdpJN2tbRs3cl1yROj0CGZvIzvYsY1OwuwNOdH8KsX2ilf1D.Z1C5OJqqRmfYRJwla7TxgsfWCfguEXs9b7yZj3GBPGAoGqnfLPOpdXSeCWxiKbQK3HZEly8JaDVFYfPs7zeeGbqfs75v1T0EXQS_qHDkKfVEkHynpCpnK4_R55ZsoCheI8NRmB7dNEjpgWJg8dho9lteSOAyYJgUciY56yxpVEocn.77jJacbLMI.0yfFEuF6AuPD5op5_VZB2U55IMfmUrcoRW9eq52tAdbg00lQNJoFaAkUHopXghMU2xywTCtHkGCZ.IshdTZSzJdBZjwg6lT80m2lTgvIJP7ZG977phsft1.ztF8xq0KP1IATNqnOWd5ZpXPt7_t0VzJdQ02bujhro2U5VjjeJmcdSIJoVkHKIrqxDBrK12B7FHHE8nbNuOV.0ak0zdygl0VwZevn6vyD8PBOjOXmtmoSw_iICdWmAbvHPnE1tR290nO4NDY94fy0.sHQpXkpIDn2QNJfC3foP9mjsfGzS3rfpeX4PktTWW45P76maI_JLlGUsNpYhnyOatdO9fsaqGHRqEqy2TuU70zfRzQFwYgxePeP5OC6c507qUSXEns4ywq4Vx9HezzJzsuKBGY25cULb7mhIT3ohz._E49wtxTH6JlchJE7u8XXER9BCPHKxJBSXeUV4GSq0M2pDaWzrB8X0F12UbecmK5XUYQeg1m0NMu5NuzeUsYzyCK4yWDd0gwn7symLXgJAA3CUxj2Oh0M212G77L4DJNO8OR9GWx9pj.Rm8MvM4LLCkR.yv7sNY2eimfKM2hPDKVDEhZHzq5Fw6hQRO0YmAGv3U7X.fO1nPtHoqNqeNlOHw4lVeGipsSDizhFCROnP0EJAxJGcfXhRheXKHoVVM4X4gW95epM97cuhu_6rUbKt8tC1DKHdQuxPDtXaXUs5J4qE9G764K8UytF9IScAT3J0kH7_1c8PWhunojc05CpPVKQ5N7sfC_P7Pm30K6pbsxLyoJ9MZYafI9GrDPeT0oLnIqVicFDysb4CGIFuKBEcbNeyhnyn_qiLoEr43iJ6FhcRuiYdedQtryFMQDv9sBuR4HL2xbbedRg8Zp.PTK8JQK3DC7LotrjNDkFk3dd.phuVQAPo7QkMYuN2X5D2ODNSGHOVeHa659D6NaiYDeUfWX1AvINsH6njDnpLBT5L52Nvs.4hwP3zgoUenbCdedVeIcKHSnZ4iEqv8k8beKg..88QKAE.N4zvPxy4cf4jx9eBtKut9QA0353EzWCQRQ_7JEx9IHFnCbztyA0WHRbdTVW3oygWQWtAWsebpzNcdhXGh6aAGROE1zW8TOYOHxilYEC33auT1GdaV7de7dckB1dkr9TSyShMuixeq..HBaajdHLIrDB2GusEdi50WdrgASL55CJUy8PROzZQRX8EAzOv5ta8fMEeBuXMCt71bQWq.f3xEKRuGQ5XBoPC4zU6qCu5ZTMWxRIYwWmAYkug4xcKRhe2SYUGWHq4uICG.zsdckOKrgnLsdjQvKTEhKBZ3YsHRmGTmQNTgtOA4mtxPYIVCIK91QlavmPaxPONPimTcvVATyXX65ws_TGcngi.Rk3DXS4BMf62kRqvWWK8h.O7Guzx7BTv9uqcR0v45e8UJxhbjd6Pwk5raE7iL7DQE8vL4gjvt81jerSWKr.rGBbYoWWqU5oJYDGw5zzWU1HO_V0g6gz6kXaaw7SGoz3L17NS4i_XWj0qp4JFIrkbZ0z9YBFpS36HrfTzzuZwfVMqSY6Oc_Y0gvW6NynCM1Krt3EnvJ9i1Ol.FpAYV1XpbPVYFE_oRZOfHO2uVin7_3wDxvKH099qisRT4uHMy5nNo8fkyE_DD95vjZ3xolK19rMgL6XcJ.L5LJ1XMVJe8aYDijWksGW1BdKyv7KY.vDfIY.MYp6l6yup5IwF0ZC5UT38nf4f9CtJ.ui0OFjGQ0F8G2t2AuUZ8gFs0v88wvakCooI1vjgbXJkE0XzMlkWYAGPj1s5XA8ywtP54Wb7VSZJZVQR_bnWf2Nny5IJBzNyPmDri2maLLJ4PZInD.dpuwY7UsORA8JjpqqP3jtanPLO3TxE3npzWij35BrEwpZXl5CzWjGdjen91eXCeVENJHkmJHvzzQP_YXfZwDuI6TvQhS39rbaMNfWbslni7fFm9pbcxXrxa8tFKaCp7JMAeJtSxJeYdnFDNbSwBa0akK5YOzaSHnKlFU65RdCE7mVxn9kTA.6flqyUiBP11X2nL8z8tcd6AI57XVyXO33GoPyqSSR1Y8MwfBDLOANua2VCuxFWnUG_z5bnmT_nMDLXv2QcPB2hvH6tnwSmlGLhK_yJHXA2tIS2GBo59.I_HW1SxUJqu3ltnls_tZQGIExe9KyyTVpWjnztElec4EJBjWnU_PEssZQRFY4BZvKFD_EsUSfuGOs.HqnHquZjp.b11.shuqBe1lnZlOG4RdyACFQXsSc3SGiDkZKPXlUVU6cZ9ixlW2coREmM2vvJLnG.XGCtqdkHmaaohxtfk6eB14egn6mB9_DZs",mdrd: "vty5xn9m6q8w8V8d2cwyD216EZYSS.8lKSBr7J_hR6A-1739796994-1.2.1.1-1Tc29fGhaCh2shRgVR1zZ4k.X19wpa.2mxRvmIw5AI9_J4Aj8fKqb_JH3i54zgN7Bft.KohIr.3Rp.kgaZEnmUeWbCf2BfEAf9WnFa8biAwYU74XOVyaB7IhTR_Ent318MAng136ILZeBr.0kcGPNk.C02dpM_pCcIwa9j5n.0cIDozNL_vnFOOGFQTzbEirozMjBaPUd9YM14DCDsVmCPRgciYKZD4UTxhn1xy9tYU9jphVIQ9UoTvKXNNoMgDGqLPIKGdjZ5g3aJpCmxQZZlPJ1wXVWThNoqPybj4fNZ4EH8hlnEUy9YEA_502tf351yAKYnDsRdNnvyDsmT4ICYorEdGUp5AEejocF6PrF_Pp6a2r5ibYFJ0flB7N0MgJB9XOjYKQ3z0ugJnsvT..p_AYl7l564r4S7cTYvkaSpuSTEI.Jp5X.rtrN9Pqth56df9thOSzi67oZbAS.GSLBLmM1JqNDW2MoXGlyOqnynxDxkYfxTEEyP2R0hui6epEDwoV0hCOjMe66PXEZsyRdJA9hhoAdGXvtRx4XYV2UMZF3jZeaDrJpk2eVtx8TK5FFBpe.uMInI2AkalHP6kUwVISdqSdd.3XIXsthmHfr5O4ZGGJvKzQHebTpwtucgo6rCd12d5.7JZYLVd_YU0RYFI68Do1u7cDSEF058AAuMG5auIcMn9b7RkE03DDO61qwrjlO6p3dVr9MWwnYQ_Cz4PRTvVjS5ch0YgEEH03pmG67vHxEWpd5mYa3wAuM_kcaP4GBlb5xMeEyC.Cnz86Uu3lXO1CslKbzHqdQ0vAWwi43a7X79rwzidaMy4yy4PO1N5v6a2aFH8bvI.P3SG.pPQOWhPQw44gZhjKKWkYW1ovNFQTX5ZEOHCfXneyt.r7Meht3iTwlHHQqj9O0Hba7T9JjdfZezTPNh_ENqpltBCKA38B1zNamYhniE8HX_ssneqvZBC7vPC4txjQ5Xh2u0S8m.YYAmxm8fkneiIFX6LGb28IhLLNQbG24lmpXbCq6ybWLiicbg_ZOKoDOWZ4d_DbuvCRbT3p4Hna_5OcteXPUaKwfxCFBS1C_elzww8O5ILynj2VtiKRc_EiZNsZ5zlSD9baSvN4otofsILAoX3rp1MCaIIeT1g6OXvKocsKeqQb6XNQRN0SRh2QTaR1MtdvaNJk9KWza9INiCzTvXBXq3I2zm0lRsXAVP7Hxw35iABfA5kIYXOmslizNdORxvGn6Li.puBmVmPiCW1cgTEBrwil1kZ7w2OkgPa6PD2gzyGWkvH0XB76rGi9LdDK1KMnN8GmYiqacD7fY9ZXCdtB0NJIpVjfL5NL2tMSPKMu2roxI.6AHjBX9s1TKiodl0Ov2FtCOqcv4.Zoj8v13qUwGNgnEYi2aPlSiEG0dZ1Ca_kkmsotGmYqOCEdpsrddxSsv.FEpbSc0OvwjCoAJ4t9VOwrPDtJSMl2TSzQZIZBN0_KIKNRAm03.xYd8f55j2axuN7._XaKhL.3iytKfyPg.AiSsS6GLx7raHw7xueyhPQNytpf3g3KjJna9iqr8IzyGZp4jhrTkEavjY8E5qYYcTOGiN92PGM7IJ8kgqOm3N.PO65uO2loTacM1szWEPWZr5dxni72yisrQAirsGNNul5pDnP1881UWdq_eebk30Kw7IKmUqb_kNKfadnB_VJ.COwHNc82Q2hRqC01VgbU1xZEwd3Bdg.Nf7amk7JXc86DCxiGyI5CF3IlvsGDqejyx_Pfj7Vloj5nKl9rP.BcEptsZk2CzVI__8_wSiHjB6Ao6eT.ziBwL4u1VqJnZrbsxMHXVQh4sTsl_py6vBYmypgbFP9C6qw9jqj1CedGo1tSaXX1Mxo99GZwR3ngx66w8ZimOp7Hm2eN2dvr_hQwUm82lezJ4oWA6ggCwe6SdKI_IPNa_QfAzeG_KJcZbg_8zWecYzvSFFCMsoHLJ00"};var cpo = document.createElement('script');cpo.src = '/cdn-cgi/challenge-platform/h/b/orchestrate/chl_page/v1?ray=9135f02d3a90fce2';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.371.6531.766?__cf_chl_rt_tk=tYG8AIPZlpiTeoGfqV9hF7xwBLGiFCi2PB1a9oak1UA-1739796994-1.0.1.1-0XnQAWlh4x.nj8bUQNGqlkRfkBc32OdLHhr8ryI0Hoc" + window._cf_chl_opt.cOgUHash);cpo.onload = function() {history.replaceState(null, null, ogU);}}document.getElementsByTagName('head')[0].appendChild(cpo);}());</script></body></html>