Recent studies have dramatically extended the timeline for recovering ancient biomolecules. Researchers have successfully extracted enamel proteins from extinct mammals dating back over 20 million years. This breakthrough pushes the limits of palaeoproteomics far beyond the previous maximum age of around four million years for ancient proteins and is ten times older than the oldest ancient DNA recovered so far.
Significance of Enamel Proteins in Fossil Research
Enamel is the hardest tissue in mammals. It protects trapped proteins from environmental damage over millions of years. Unlike DNA, which degrades quickly, enamel proteins remain intact even in extreme climates. These proteins provide crucial genetic and evolutionary information. They help reconstruct the biology and evolutionary history of extinct species.
Key Fossil Sites and Findings
Two major fossil sites yielded these ancient proteins. The Turkana Basin in Kenya, a hot tropical region, preserved enamel proteins from mammals dated 18 million years old. The Haughton impact crater on Devon Island, Nunavut, Canada, a cold polar desert, produced proteins from rhinoceros teeth aged 21 to 24 million years. Both sites demonstrate enamel’s exceptional preservation capabilities in vastly different climates.
Methods Used to Extract and Analyse Proteins
Researchers used advanced mass spectrometry to sequence enamel proteins such as amelogenin, enamelin, and ameloblastin. They applied strict contamination controls and exploited certain chemical alterations in proteins as markers of authenticity. The studies combined palaeoproteomic data with geological and climatic evidence to validate their findings.
Evolutionary from Enamel Proteins
Enamel proteins reveal more than morphology alone. They provide genetic clues to evolutionary relationships and species divergence. For example, the Haughton crater study revised the rhinoceros family tree, showing new divergence timings that contradict previous fossil-based models. Enamel proteins also allow estimation of biological sex and evolutionary timelines.
Environmental and Geological Factors in Preservation
Rapid burial and low oxygen conditions enhance protein preservation. The Turkana Basin’s fluviodeltaic sediments likely promoted swift fossil burial. The cold, permafrost conditions at the Haughton crater also helped conserve proteins despite freeze-thaw cycles. These environmental factors are crucial in protecting enamel proteins over millions of years.
Implications for Future Research
This research opens new avenues for studying ancient life beyond the reach of DNA analysis. Enamel proteins could fill gaps in the tree of life across deep time. Arctic and Antarctic fossils preserved in permafrost may yield even older proteins. These findings promise to reshape understanding of mammalian evolution and ancient ecosystems.
Questions for UPSC:
- Point out the significance of biomolecular preservation in fossils and explain how enamel proteins contribute to understanding evolutionary history.
- Critically analyse the role of environmental factors such as climate and sedimentation in fossil preservation with suitable examples from palaeontology.
- Estimate the impact of recent advances in mass spectrometry and molecular biology on the study of ancient DNA and proteins in palaeosciences.
- Underline the challenges and opportunities in reconstructing phylogenies of extinct species using molecular data, and discuss its implications for evolutionary biology.
