CINXE.COM
Just a moment...
<!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: "royalsocietypublishing.org",cType: 'managed',cRay: '91350af98b254c05',cH: 'gB8MpA3hHnpYX.Y7_FLCTxzIQ8tBE27he4iTgUTAWmI-1739787606-1.2.1.1-HArF3VB8qtnPTpDugLaZGcZ0kQBuVc5S83L9pWwDSXsH5dliYjpOMn6lTmn1W7WU',cUPMDTk: "\/doi\/10.1098\/rstb.2002.1183?__cf_chl_tk=W1_JZ8r8VjfLZUs68_89IK388ZA8uXJo9rJRi.at_tU-1739787606-1.0.1.1-_sL3i8__5cyiOXa3EZ.G4TIe4X6lPPdtLo2t_1H9hGU",cFPWv: 'b',cITimeS: '1739787606',cTTimeMs: '1000',cMTimeMs: '390000',cTplC: 0,cTplV: 5,cTplB: 'cf',cK: "",fa: "\/doi\/10.1098\/rstb.2002.1183?__cf_chl_f_tk=W1_JZ8r8VjfLZUs68_89IK388ZA8uXJo9rJRi.at_tU-1739787606-1.0.1.1-_sL3i8__5cyiOXa3EZ.G4TIe4X6lPPdtLo2t_1H9hGU",md: "Sj9nEjsa9YhboI6H9ZaopKVuzK3N_9jISc55_ia8u0A-1739787606-1.2.1.1-hn3_4b5pwMDUyi25_WF7sIHTnv827rzFdgm3Ys2VqfQOVnQ1qg3F.pgzzHHCjNgwyAXXVWMfe9n8XutJbWFu2zWIJPcZOe4ZFR1sdCFP.VIyfsNODDtXU_aLXSSUt5BXQAEHQedikNPxWqT78EAALU_zpBky0WP6OD7G20tnzikd68guBSkQpDkVH9CLesm6PYMnOBdsOeSyUQ1xVNM9A3BCaUiVJQugPqkRMVE4G1TO2uBJDYh8wrI6683xRPmL2dJYpIWxKC97sWFqm5TNNLa5ajkNfAJzC3059iMLgsjHzUrgFC3PTsHLU15XNgoLuRRxcV719aH27MSsnaOCq6mF2Yp59K.vLEQBuRYShO4jdI76mAHQQSVj9xBkCiaAXntJMUQ6Vi_y011UrSLjf4w8aBGOJe.iXQBN3zgNIjQQuLFD_WxE.hrrOd6ISlOY02KDwb0JSW6XFi.6sYP.mcXDh7PshPnZVTCos_nGV2qrlUYUWJ_LhroRonAEjsLhC_n7UgUsjTVYuCaZkAV5_vEBCzBx9xyp9QHeeW1rzhuB1urv.HAWgZkRtx28XW0EhLPTgNOKPBt3S3qFzaxK7HOVBFCZtEsjgC3Kj3l9XiJ9VxgP.02hZGSmZbLiGloNUsy0rcGyRJv0CC.TRbFM231gd8BqjFuToBHkM5.e6VvcBV3KQXDFBXkUYxIoS0yoxgtKQrdGU2Q80xhE6kyHdTJlwFgLcbP1rZutp7faqGoli.6qhNkRKAZjxrXb092q9KQWKI4VcJ67u5BcwXDeL48qfhy5eO3OOP2y5JDxeWJ_XJTVhz1PTiHZBdc86Y.QwSBuABIdrRZAxnOSkKVcTPzzIb1KkoYJWNGBO.WgLmaMyxs.cVKskTUv947mbLdVzO.bIVKzh_QKVZNnW8n8SJVwFRxpGxpVaor0KbR_y6zJZD3wrEqt3U7WTbMhBi5zE4wO91q5Xzc3JhfnJpzZAnW6R4jyIYgmfolCNU6FGC0woIiCq3RfOC3G0qbSyVC5UtjvqErRNUHB5EQn2sQpjg9x2Blw3an_X3NIZtG71YpiDkwSZrS49OIH3DJFtu8M1bpWFLhK9cxiOt9ViBEZYyvLw2wpqJk543HboDt9l1uYCE8bEh1Hhez8kogoVye.S6kkWWnVL6hLgR4YeE6UrZD6N8Q61XO3bJ4HtsF.0X6VepIhpBISL6H1x1lSSg2bRDe0Y4ya8_B317mcNwbVxbGfOU51YLWqJemqNR.P74hCrTxBzr_sbNw9YvYMFs3QjQ.QEGEiWiQKiLDC8Lv3mU.5gGQrqEwfwkaXebI0IJXfIzcGt3zlHw_DUyeCQyKPiUMuhvws2fkyp0wmDn.lKkNdMXdF0VBQem0VeOTnwPr.MDpZM.j84koHANOWZreNV34AABpSZQltvFzNaryHEDzDGXvdhsSngYRKCNzzuIsVPaCyvSKba4fk9JRcFj0XE1UXDO94C0COlThU5fbqjQaEpdKjkSvteL.bZZ8GjBYjOn3TjDdmoZMcEpLOOe2tsTBWoX3iGBNKaeXFza.khXF6_TkUQw3.bIfPCZplZq0gEGskUMdTBsTnxRxem5y7bvIcCym6CNJSq80biC6iuebu.xDnvt2J9GOnYM2Y0gtq6yd9uqbKqGRXKXRWXFcH6J7FXDjrp6SmQLOhxDImmM6Whng7wGswo1kOsdraF5Ct1NJCqTck.M2RGxO1pCkeRuNA44lKTfpzE8UUjR_i36sMEuSggftH1GqZyq3qGvpMXEyLqaqpV_69vvObtbweT_Cz81G_sbinXHWiKMvH5jGmG_SPeEcZWf5wipf8fg82MNfNIvWLc37sAA.P1hng1UxKej40hk.sEzK_NfPVU5qrlMIUIjQ8dLxbt322B6GFS4IIvlqH.twRglbpGLO76ctBGtrUNvbV2p9OGQveeEU5ul8ySSx_U8qAhclcQV1AD9Enl354O072bwAFlzm5izxZVM3M.szLkRGvLYaqkeBLJTTYdvAeaSxTie0BnR2jGu4K1bABlPzL_t0Gi8ilJALnbX0V4rbnppM.lqTvJoNS_ba75RVtzNX.jawJAAbgm6Bg0tiEukDchGFKjI5mxgi3h5bM7ADXJr4tGpeNKn0sH61ZxKbyNGwG97sNuQv98KMtJHoknRklo9rCzXZi3tKsrzBxVr9wGlFu7dfMP1PJuXwX3yDx.WcitBsys9_3pHjcL7WaBrBQ_A0kryeK2jv.4_MFh6YsbnpSppoMoDkwpbEsId347ZpUFcJI6Rn_PDdzjrqc.H7w5zWstPKDy00psxB1nrLd_qTVrwOHCCFwAl_mJV61OoL5QWfm9EG.LuQb4V_Eqpi4S0r09gv.VJbZk_WdOjlkCsgv_RAzLdeLS9tuJwZrmi9pKfh23rTusILgnBV3nW5UwXsqxh8DnuGey.XzLpWhqV7dhfH7CSOFqVnKZtZG_2TLeXy6Gyre1eUYQcFSe9f0ncBLrhWYGERjJoeqfiDURWrExvdntB90PwEMYFUe2yFtqfyUjiZUzT6KN8UpsIIG1Qq_Mnshz2rO0PML_M0AFw0QsiAWX3zkdNLgon2TaA8g974fqzI",mdrd: "oSPZio7wM7lUpJWdRxl602KJ_c_gW6.bDDRGm1RAr0M-1739787606-1.2.1.1-yApYitaJu2MwCmAtEC0iqAxZWLVtDwyt0gVHQkMfYIXjiN6jLe0PHJ2jYunbgQTrzEekgY4eCERR6Rp7T4ZAOPlCCTmwRVTkRNAMjiKqj1uXpWo6wMf1ONHUzzYPnb62.lH0lk7aMh_2kcBnXlVUOZ1PnsCCJTnWrRGbNJklNEpRASxGoVTvoyJLEEk13CQHuplIH4OelvHWPcGGd.Fqb2zWLb.9eSTwaRtgTyd.JLLDjX3XjHxDO4dIFxbVWXf4Y_g18uBmkr_p_TxkrLuhEdrLoNQyBqDAoI0IwM0D_nsyNnfbVq6Y6mFe18x0qE.ZxTb5rr0fefAD6Y1BJ45Le0UVSF2SqoOnbjXrId9LZGFffLQV2mrBqSGQTiJMAMv10MgQ5ESssapc6GKpws5_UFRglEVyBqVhbHGLveMMNk7OjzepBWUBG2AvgTbeZ6vA3TH9S6msBhYhXKn3LnoUbaIB.oDVybW8_1bU5rKN1vjEEXNHr9mg383nBU_fqqOMqJ.qDb3waeyXdjEdqS3UzbkK0UdxEdqIZZe8KTEpe9VprJtNTZO7DanGs9TKKWV1ceOKgs.RiEJvp9Bqccx3qpEJh39U63QeLV5gb3YZkq91ZB49SCdca6k_t_4aUPuPsCy0PQkLzI8bEm2c9bOiHc26NcORtCjbxwSR6GFMQjdkbmoQkTOEBmSG4N3UEv17LYLCfYDrhymFzMfSDdCQ_VGEhGFu_5dNzx92GUgZYVHnt2K7Vtt6XfbV47n_Dq_qQgW1M0NJHEgktRIuPnjgxU3DdMsmDmtpXKiKHxyztcUH1Dq1b4J0EdDASr2b3rWdjUYQsws5BVeDr222uFqrrnOcnJS54b6dbfx_TvmU.E1ueUDUw2LuWo2n3pQLt2aJ6yrPiY9_ns325K.C7E4w3eDAl7ijGstBTbJXC7ghGxGZCuTmH2v8Y1bfMlVDSZ42D0ohj_PJcM.QnmHrFVzhemb2wi.A9DJbK_pFi2JydWkhU.lJy_a.jtPPYT_R9kGxzPIB58M.5F7eK2m0dHRBhOg6irjam6kng2IH3w8XAaSAXcVp_vodv0Eeht8LLOP.XJEy1WluqwrskizpfT1nYixL.SGfPkVd_lVQb1NWBTtXiiQoHy24KGHGdiBWvHOEOiXlTzfA7LSJaNJwDCgPoC1u38ZWB_UYq_s46bu.WFaA3w2rG1ZCoebJDKO5Ip3GnacrFcrL1UKrZyXp7Vw2jGQ9qYPwuYF4lMfp0uOGxoVJWJmeAQJQJgkgv8eyy7AkFRobGlwKLYtSjWNUugY98fMSNkSaxawrT6IfV.L8mNfHwbICgqE_RSI0hADiidJvwGklSx6kGRsLoEN.hWhcYh6rcdjvfZGLggoIlFOuKCJuhnxLxdiomkTeEj8Mid_ChsZ1GpVjT1Idpuj9dv.X4YUM.6weCZ5iDrYR2rN5XPmxCQgLEb3rp9zyS9b8.dzvbpOdHXJLvs1OhdGMX9tJYThqIuCmvHtL.GTEwFm71xpgPeT5VpnwEyTnbz6ttN4nJWBXvJufJ1Upr9WCP8VxlWRMUof5V.eGWTfdUjCSx4QxD_aIjbR4hxrhCO_J4RpFZU37TJgPnlTZL98.Pqdq_Flq5LctJ5O.q8562BsrRUJ35FM_gO.tV28rABOBy3orhtq7ecGFeR9CZZWGXaUJo5SkdsDryizhRremjePp3cDX985TT1bgAfDEfL5paCbYdJbB1jILcUjRVzIEKJTtRQhYtYSvkclYu8MhTODOyhUD0JYbKkJ0VHIaThmHEuAEl.DXORJST8PuH6CZuNJqQnYIu_XGM.7Mnsu.SSq8FcZFEX7EWr0kGhk7xq52mR2ntX4AvO.MkvPYz8e2pv4QPijNH0uXxfNq4WjXiIAAeLeRATz3xoviJ7tlopIHmdecatftUI.ZdEQJo4Fr7Z7xlpge0P_JblqIwdk2drn1JcwTf8OEYXrpk2mOWZ931lsL0GwMmkKy1Euc4JKmMXhGWg"};var cpo = document.createElement('script');cpo.src = '/cdn-cgi/challenge-platform/h/b/orchestrate/chl_page/v1?ray=91350af98b254c05';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\/10.1098\/rstb.2002.1183?__cf_chl_rt_tk=W1_JZ8r8VjfLZUs68_89IK388ZA8uXJo9rJRi.at_tU-1739787606-1.0.1.1-_sL3i8__5cyiOXa3EZ.G4TIe4X6lPPdtLo2t_1H9hGU" + window._cf_chl_opt.cOgUHash);cpo.onload = function() {history.replaceState(null, null, ogU);}}document.getElementsByTagName('head')[0].appendChild(cpo);}());</script></body></html>