Since the amino acid sequence of a protein reflects the DNA sequence that encodes it, proteins in fossils can help researchers to reconstruct how extinct organisms are related in cases where DNA cannot be retrieved. Proteins, which are made of chains of smaller molecules called amino acids, are usually sturdier than DNA. We know that some molecules are more resistant than others for example, fats are tough and survive for a long time while DNA is degraded very rapidly. Archaeologists and geologists hope that dead organisms (or artefacts made from them) might not decay entirely, leaving behind clues to their lives. The pattern of chemical reactions that break down the molecules that make our bodies is still fairly mysterious. Thermal age calculations demonstrate that the Laetoli and Olduvai peptides are 50 times older than any previously authenticated sequence (equivalent to ~16 Ma at a constant 10☌). It is the domain with the strongest calculated binding energy to the calcite surface that is selectively preserved. Molecular dynamics simulations of struthiocalcin-1 and -2, the dominant proteins within the eggshell, reveal that distinct domains bind to the mineral surface. By tracking protein diagenesis back in time we find consistent patterns of preservation, demonstrating authenticity of the surviving sequences. Here, we demonstrate the role of mineral binding in preserving the protein sequence in ostrich (Struthionidae) eggshell, including from the palaeontological sites of Laetoli (3.8 Ma) and Olduvai Gorge (1.3 Ma) in Tanzania. Proteins persist longer in the fossil record than DNA, but the longevity, survival mechanisms and substrates remain contested. Centre of Excellence in Mass Spectrometry, University of York, United States.University of the Witwatersrand, South Africa.National Museum of Tanzania, Tanzania.

American Museum of Natural History, United States.Complutense University of Madrid, Spain.University of Cape Town, South Africa.Nelson Mandela Metropolitan University, South Africa.Arizona State University, United States.University of Sheffield, United Kingdom.

Mineral Books by W.E. Wilson