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Inside 72 fossil teeth from horses, rhinos, and elephant relatives, the molecules persisted across samples spanning tens of thousands to tens of millions of years.<\/p>\n
By analyzing those remains, Lucrezia Gatti at the Max Planck Institute for Chemistry (MPIC<\/a>) documented how enamel shields a protected core of organic material.<\/p>\n Across that span of time, most losses occurred early, while a smaller fraction remained stable for millions of years within the same teeth.<\/p>\n That uneven survival points to a layered system of decay and protection, which sets up the need to explain how enamel preserves what other tissues lose.<\/p>\n Why enamel lasts<\/p>\n Tooth enamel lasts because it is almost entirely mineral, with only about one percent organic material left from tooth growth.<\/p>\n As crystals harden, some residues become intra-crystalline, trapped inside the mineral itself, where water and microbes have fewer paths in.<\/p>\n That sealed position also explains why East African enamel<\/a> yielded proteins 18 million years old, despite tropical heat.<\/p>\n Those findings made enamel the obvious place to look for an even older molecular record.<\/p>\n Early fossil decay<\/p>\n Across all three mammal groups, amino acid levels dropped fast during the first 0.10 million years after burial.<\/p>\n Depending on the molecule<\/a>, that early drop meant losing 55 percent to 96 percent of the amino acids originally present in modern enamel.<\/p>\n Once the more exposed material disappeared, the remaining pool changed far more slowly, which points to stronger protection deeper inside.<\/p>\n That two-step story matters because researchers can now separate rapid early decay from the long survival of the best-hidden molecules.<\/p>\n Age shapes decay patterns<\/p>\n Burial setting mattered less than age<\/a>, even when teeth came from lakes, rivers, peat bogs, coal seams, and rock fissures.<\/p>\n Scientists call that burial backdrop a taphonomic setting, the place and conditions after death, and it was usually not decisive.<\/p>\n Only lake deposits showed more overlap between young and old teeth, hinting that some local chemistry can blur the pattern.<\/p>\n Even so, the overall result held firm: old teeth usually carried the stronger signal of loss, whatever the surrounding sediments.<\/p>\n Which molecules fade<\/p>\n Not all amino acids aged the same way, and some vanished much faster than others.<\/p>\n Aspartic and glutamic acid groups fell especially hard because their structures break down more easily during long chemical wear.<\/p>\n Serine also declined quickly, while leucine stayed relatively steady but told researchers<\/a> less about a tooth\u2019s age.<\/p>\n Those different fates mean future work must choose molecules carefully instead of treating the whole surviving mix as equal.<\/p>\n Horses held steadier<\/p>\n Horse relatives held a steadier pattern than rhinos and elephant kin, both in modern teeth and fossil<\/a> ones.<\/p>\n Their starting levels varied less from tooth to tooth, so later losses looked cleaner and easier to track.<\/p>\n One striking case came from Messel in Germany, near Frankfurt, a former volcanic lake site known for exceptional fossil preservation, where 48-million-year-old horse-family enamel still resembled modern horses more than expected.<\/p>\n Messel<\/a> is famous for exceptional fossil preservation, but the broader pattern did not depend on rare sites like that one.<\/p>\n Reading time from teeth<\/p>\n The team also tested whether amino acid patterns could estimate age, not just prove survival.<\/p>\n A computer model predicted sample age with moderate accuracy, showing that some molecules changed more consistently than others.<\/p>\n Certain amino acids also acted as reliable markers for estimating how old a tooth is because they changed in steady, predictable ways over time.<\/p>\n That opens a practical path for dating teeth when other clues are weak, although the signal still varies by animal group.<\/p>\n Beyond protein fragments<\/p>\n Earlier enamel nitrogen<\/a> work had shown that tooth-bound nitrogen can track an animal\u2019s place in a food web.<\/p>\n Because amino acids carry more specific chemical information, they could refine insights into diet and reveal seasonal changes.<\/p>\n Researchers call that targeted protein work paleoproteomics, the study of ancient proteins, and enamel may become its best scouting tissue.<\/p>\n A broad review<\/a> had already shown that ancient protein studies work best when researchers can authenticate truly old molecules.<\/p>\n Limits and next steps<\/p>\n Even with this long survival, the study could not yet tell whether the molecules remain free or still sit inside protein fragments.<\/p>\n That distinction matters because intact fragments can reveal ancestry, while single amino acids may work better for diet chemistry.<\/p>\n Since MPIC\u2019s method needed only about one milligram of cleaned enamel, museums could test rare teeth before using harsher analyses.<\/p>\n Future work will have to sort authentic residues from altered ones, then connect those molecules to species history and ecology.<\/p>\n Broader scientific impact<\/p>\n Fossil enamel now stands out as a durable source of biological detail that lasts far beyond earlier molecular limits.<\/p>\n If researchers can separate the surviving compounds cleanly, teeth may reveal meals, seasons, and kinship from eras where genetic material no longer survives.<\/p>\n The study is published in Communications Biology<\/a>.<\/p>\n \u2014\u2013<\/p>\n Like what you read?\u00a0Subscribe to our newsletter<\/a>\u00a0for engaging articles, exclusive content, and the latest updates.<\/p>\n Check us out on\u00a0EarthSnap<\/a>, a free app brought to you by\u00a0Eric Ralls<\/a>\u00a0and Earth.com.<\/p>\n \u2014\u2013<\/p>\n","protected":false},"excerpt":{"rendered":"A new study has found that amino acids have survived inside fossil mammal teeth for 48 million years,…\n","protected":false},"author":2,"featured_media":554119,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7],"tags":[49,48,66],"class_list":["post-554118","post","type-post","status-publish","format-standard","has-post-thumbnail","category-science","tag-ca","tag-canada","tag-science"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/posts\/554118","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/comments?post=554118"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/posts\/554118\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/media\/554119"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/media?parent=554118"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/categories?post=554118"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/tags?post=554118"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}