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.pnas.org",cType: 'managed',cRay: '8e9128a33f523dd5',cH: 'SSNVn8.bpLng08LBP8XIdHOZRUbWhMwyjzxD3yoEqt0-1732700447-1.2.1.1-1QxGLU6gm7XDtk0aXzM_IZV.k6iMP4RLe8I5VBeXdrLzY.P7uOojIiLmyjS_3loi',cUPMDTk: "\/doi\/abs\/10.1073\/pnas.2114227118?__cf_chl_tk=n7d.oJBPMetxvvGrHiUz6Czs2sXe2Is6Z7aYQhQXilI-1732700447-1.0.1.1-Qz4twZQXuOavFSHag9DnYVMWXaXk5oKvu.jNW9tOdN0",cFPWv: 'b',cITimeS: '1732700447',cTTimeMs: '1000',cMTimeMs: '390000',cTplC: 0,cTplV: 5,cTplB: 'cf',cK: "",fa: "\/doi\/abs\/10.1073\/pnas.2114227118?__cf_chl_f_tk=n7d.oJBPMetxvvGrHiUz6Czs2sXe2Is6Z7aYQhQXilI-1732700447-1.0.1.1-Qz4twZQXuOavFSHag9DnYVMWXaXk5oKvu.jNW9tOdN0",md: "Sf.z1MRB5ueep5APSqXeuqFNPht_YOZ3ZyBZeaVtFqU-1732700447-1.2.1.1-RgRv2j.4GkzSyxTwDK8HyVTxvALw77mGO.OH.LHwDWSjoOQEYuapwpuq3puI15GJCJpfHlTQ3HI23ckiqi5XNnrCvfMCQ2ZImk3Aq8pvYnIuI2sL97JLQ6Fvtf6dKZ_1dHtMCF8Zqv3qWJ9XSkmXAFKm5DT9CaYpXdCQVu9SbcVTVy.7O0trMhMpmDlnPiM.jQHsney44uGFSV24obR_82qv1lN54GWjsOUMiGVOttb82arm0rnb2AKZT6X4Uezi3Zwbiwzys9S30NnLNdFxOw5arn_yojcj24XOZBZOFlyVWrvXhWRIpGuTS1U7eTfICjUR051LHEL5csJez77trSGe9APXHlkipz1q_pWWgwoBAYif8t1ae_WfEqcUTH00Up7FRN1skpGRjfbYdJuol5x1b8Pi8.gQl_jFgXx.Xxm3S4z.9oedD7AtRWNlKMTJhFkBkENu1a0pWcZsBvPZgRXTA6xGaII6_qnblyLlOPo4mUMBGUljkRvvBpJkzojtB0MHM23IklfTyQcaPnZU8m.cDy5waA1rxIKyTQ2Z3dCAqWvQ2IHKLNHUofQexbfhD6z_2eX4sZQ1uvaM_qoy5bjuAgpfwfjF7cEPeMgdMkgi5DLFgmm.AiSN1j3VkZJgpIcY.kpdevolhO0U9Y_tIwfsJK9cvtA1YiJQf8VoX.bKv37OOMgLlF89IRFr2TWhQJ_KeGLMvTOIzRpomlaGkVpz.rdJdRxcwmtlOZ4529..Ob501D9Qo73Wnlemp0ePirnYA1RxfgfUHHuBwv3SMOqX87s6nU.Ipbc0RG4bg_UTcXCaGEXxC_1NiHkQPpJMILqjAbl7M7re_6Oqqk6bhTqf6Ie3OMt5COtEytPGN6FIDKj.5yozhd3meXkaVmkFD6I9q6D3AReiZqAiitPSCADHRDnQrGaKJjMGMFCasPFDLgXbtNURpcaEJwoB64fBmrtusX_SD0JHXRpOSkgMBmcGAbsREg3vPxdOI3gJe4t4QhshkGZOFOavuGK4t_fIO5sonuOCI3RM5FQRiITwh_CxIeLNM.vQnb9wqnFoGUE9BGOLceXIOC7KGRSFnqzG.5dfnRRlUqHP.HM3r40A3Ss.UkTgIrHkTTcPtNHioxLelJz4hVj_z_AJl9t3F.SfHg9jEYCOO9oNRfxcembFSBEi_3QufUw41tK7syByX5_E2DgmYvtLWjuyt9OtLFokAdHjxwHAZwzJe9SrwClTKIPWWfoLRlbXGdANoOIBc2oW0G923b3Y3qs4uocBKtBHW9u_vAyD61vD2OkxX3Jb9xMcTxES_ifFppyjTqhQeWQ.LNbKVxo9p1ebhvO_NxLzMtwJO2fu3fMWQEGxurs4AwCE1IN_UAZhx4auGw4UKOduxSr1RtFzWgJ56cXCooyFqAzkKuq26_RoInhOxM8ASRSdFVV2ps1MibJGg_0mQ27TUVCRzz8.8NYnELElEsTMY_XTwHva8jgJCexJAHYtebKNQDesg8_JYxwe3PCvE5Gs2y1xTWgVM3.cOM2UfBiUjQia8y2I8DgXxjlIGZceQnS2qg.irg51_VBzhrxYCx6oHl1G_1WMqkp_Y3JpnVXJ5I._0OHCA90N54DrGJawFWnJqLNqZjvVdUgebZnrjNGuKLaNczaN0B8_HUldpFP.Gfedy91MWUS8ma7vd4uIOyKZppbBxyIkt_oKCri59T1995fouuzS_4IpAg8XbHz0fm3zmZtSHHldToOh4bt5uPidecRYxND2y66zIw88rS9d4LMuZNv9or_K3jt2VVrXRLJze7sfuZ.jhRr.qG31B46vloE72DusnIQzh34S2bB37CZFPbXEyD1.0OniZSOQbihTKuhaQIndjfC4uv7aHNvMxvoVjZ0u_fs1GeVk2tcVFwXHedQtTK8pf3QQYQZOaZo0SjJIjZcWmdyi7JPBzRIQyZyF6vxz.oRNTscSv8KeOtuEmX1xpbX8nQ0xKkW_RAI7RbegyjQ3V828jbBH02MwjH6TZvp7y8IYQopLwGUT3TAbwpF1S2Ehftg5iyF2hAlQH9O8zl_7BV6RtAhqI_G69bdEvCIw4OHk9cs2Kf2MHiOimoz1oTo6lOgHDoYsWzWI79tyqml.G5cW83XRfDWDMdEOA5qmRrM5STGK.CCTI9ncIQFnLB9Vcgse20Upjqhdw9DpfE_ukvAKDHXqTY7NYSK4Mf3UBICFs7hL7Dek5iBzjBSfCa4ekXuwYa5Pz2r35v9yjFpHLmK99ImXIZqy70F3mpMakTlhPOi.Sk47Nm4M3HwBEnzEBmEPT.xvS7GWpx5XtufqPdLro5rCFE68_uDCehb6l64TSc9VwzBZfoW7FBRZIKuszWyDVATZBtCpGg1YWajWOutpVZXWyrq4gS2KxKEgfjqJlpRzupat6Yfqql0ztGJH8anaSFAglSCS9If3HjbC_wr_hCl0woRrOGRImJsWkleLMq8ThJGgj8i8.n2y6AVEK5QioLtBZ.oyAyyQeGM5JU9UD2l5Mj3fSdckVIOnLSguca4cgzWtBpX.hrYBqQNz5BLjfJBEPupbtywSry2lV.827ymAYo8eohM90W7EmrkPme1XGucxHCONtld37sqPXJUNyQVJ1uJagGrRyVEJ4VzX9iXd4WOYkZthxyYGBwXi9JtAWX.5wpRc3D5kUSOZKJgrjixrDA1xc4rkouqynXaRVJ5rULoixsbnX8q8ZumDM.nK6p4.XlJ4BZfuVqLe6vhOrzhmja6CizD0EcMc3OJV6uVmJpRz3XFIxeN08z.KxHYVJPb3_V2juvbxydtm5BbUgAVXpd5lGAP8neaznQ0fpLug65qViv0HzHyNHyA55jR_ZQXCK.PvoPxkAFYoioFi__FHIoqySFUw79rXdQmEYCA46Z9Q.mFB91VH__bb.hSr0pJgNq0E_vNKMN0EbEGNBIVdDELsSrD1nHATtFB7Xx7hPSBl2Z9J03a5ypdJjsU0JCM",mdrd: "J3Y_6J9mtDtIfsDAhLsP0GPjXcl2G.18pG0NC8nNzgw-1732700447-1.2.1.1-yt5tTr_hHPmDW_qReYKXVqR3qwV9xLkro1OmFjNdwvkFoZyoylKgxiE0NsIoqXf.iumiMc5QmwCT2Gpd6nIpUbPPmfOtuoPoPSmczhO5yG8JWzS94_KAEafBhRMca.Ntk4TXZGc0U.0SrYo898BJBCJT8IB9Ox.x6jC0EIGeCTqJIwGJCjfOTY9zF9panmmJkxst5b8kVeQb90tNCgvMIbjM8go.A_esRZo_b4vDSYzUxObIRUX315WR19jOzx.peMuZg3KkSHEPDJWzjTZJl6HLUm.Pk0aHhrLA_n0uLn5m4NJZnX6fn79FfXNymGDLNCmoGd0LxpP4BJhGsY9iHOwL6.MxeItWtpn1A6s.ysC5KhbMAYbEamK6TghtP7fXWrOI1TQ.8nOIU2oatD73Ct9Qzfygn69xET1qdQPnAad2SYu2uHRNQGqWz9vuYda21juTbE_fpFEy9GD2Nr.VgEHggifS9Kda8Xvu8FzPpWr8QB1Q5zFjTQ9lXhMW7dFlwPnfd17Ur9Hqb5QEXJ92bANuoqF2gJ2DvcO17.7lKfvZLn4QXvv0SXNZY_tSvLNiMMp9pcDhFaXGHDVDx4zVkUic9sjKlvQXEQsdpDxC.ze.C2EAB4iOxsUHN8dPpoFOIWnPsUo9pOmjC7FFO6oebzSrQjBjxczmQFsFF7O9fQagXbu1ZijaMoeKrgWQIp92XGpgKVg6E53DXy5xjzFiUdojMj2TyyPMxJDWk_0odoKIZilj37dPql1.PxkSi6wi6oZnLdryDfz4gvwTEURZuOpB7OtV7a85x_oRZDp54S1kqpQyeFTIGpLYMYOuZimmYVl4QymvWg6sLL8xIqh_K8NxAK_HRnbWd2wi2Ab3HME5yb4c2Q4JHENlAu81wkIa6IS.ZACc1clwM_gEAbii9_naoAy.VB29fDH.n_PtDx1bub.c0ROgVmuu2LikvcY2.xBtv5bK2uF.e22RNtvtbbr_E4Y1J_8FZ5UmqrDOHLGnSJcPjx0O6.KwQzFVYOL.v_qCs5noQ3nrBKbdN42BsjCsyYlFlD0Pj5RDS4wwmsgSE92gOxSsqHYvaA9OI9y2oU.O5igqc3EeeMiliRbVN0Y.bGf5Xv6KF7Ygj4HciwM.PE9w7uNTU6.17_Lb6FUSdubtZwpxc8p2oiBruceiIcFU3o8o1Wcsjq6zyPqU00efoVvtMRRW2cBSAmz93hXGwXk8vtuhGsKb6BOODeIz.8cA1RdeyzmxOYcPVW7qOawkvgHFL2WikoGDk7ZhTwfAcymRDWB4wxmN.VTTHQnl066OaUJA.gFd_XQJ_2no0T7Xlemer8MlZjJYmUjK84UdWL3naqGKtZf_6WTlckedXxGQlQaS_USUWjv43CkQUZgof2jXrNv_5PiOyxOaPUgy0fzGfRg2IUaaaFuZoU4su6YvpiVQTA8Kebboy1hT.lc4DpLVJiks89ZzE54G5gEO7wDLVFuqCxBCM.F7ag3yVafa2XHyy5xN.xcwg_ooJVoNr9y1fh7gPLtyG1z0.JnXghSf7t84vm4UldUusldn5YdGjZuz2PczdcP0BehvxmmYVaP_t_5jadxQ1thJhfO0KsUxl8LQnKt7AgD4hgJOXPM9Fetv.mRrOeZGk7j3CyFZfK5_Kc91tqNnZYwh4JXEI1XZiBV0dMM1jObIwg0IMZFKYDqw3I4StMls_luBBQHmoo8Kf6yuw7vh6Jim39p27nlk3rHhSBHwG0fA5de4_xBeZLANmWhiZ..EeaYgx8JipGitm3V7DIc22wSLRFL19n61GF5MkgxNl4jGDtqww9Fed2JlFNe3ySdRtB1Z_eH71xJI2l3MSTfqdJqSPRhBCxu672bxUp9L4Z1rdIY0xXK55ubGjGpniGFYYInpxWKx9L5uN0r0mb7idV1iSo8vJP3L136zSgdtuh1xTuLpCA"};var cpo = document.createElement('script');cpo.src = '/cdn-cgi/challenge-platform/h/b/orchestrate/chl_page/v1?ray=8e9128a33f523dd5';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\/abs\/10.1073\/pnas.2114227118?__cf_chl_rt_tk=n7d.oJBPMetxvvGrHiUz6Czs2sXe2Is6Z7aYQhQXilI-1732700447-1.0.1.1-Qz4twZQXuOavFSHag9DnYVMWXaXk5oKvu.jNW9tOdN0" + window._cf_chl_opt.cOgUHash);cpo.onload = function() {history.replaceState(null, null, ogU);}}document.getElementsByTagName('head')[0].appendChild(cpo);}());</script></body></html>