Laser Technology Unlocks Secrets of Darwin's Specimens

Scientists have employed a novel laser technique to analyze the preservation fluids of Charles Darwin's specimens from his historic Galapagos voyage, which have remained unopened in the archives of London's Natural History Museum (NHM) for 200 years. This research is significant as it not only enhances understanding of Darwin's collection but also has broader implications for the preservation of fluid-preserved specimens in museums worldwide.

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To investigate the contents of the specimen jars without opening them, researchers utilized spatially offset Raman spectroscopy (SORS). This portable laser technology allows scientists to measure the chemical makeup of materials by analyzing the light reemitted from molecules after being struck by a laser. Traditional Raman spectroscopy is limited as it primarily captures signals from the surface of a container, but SORS overcomes this by taking multiple readings at different distances, enabling the identification of both surface and subsurface materials.

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The application of SORS to Darwin's jars yielded significant results: researchers successfully identified the preservation fluids in nearly 80% of the jars analyzed. The study revealed that mammals and reptiles were typically preserved using formalin and suspended in ethanol, while invertebrates, such as jellyfish and shrimp, were often stored in formaldehyde or buffered formaldehyde, sometimes with glycerol or phenoxetol added to enhance tissue integrity. Approximately 15% of the jars yielded partial results, and only three samples (6.5%) could not be confidently identified.

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This research is crucial for the ongoing care of Darwin's specimens and has implications for the management of over 100 million fluid-preserved specimens housed in museums globally. Wren Montgomery, a research technician at NHM, emphasized the importance of understanding the preservation fluids, stating that it could significantly impact how collections are maintained for future research. Sara Mosca, a physicist involved in the study, noted that this technique allows for monitoring and caring for invaluable specimens without compromising their integrity.

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While the study presents a breakthrough in specimen analysis, some critics may argue about the limitations of SORS in certain contexts or the potential for misinterpretation of results. However, the research team has demonstrated a high level of accuracy in their findings, which could mitigate such concerns.

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The research was published in the journal ACS Omega, highlighting the collaborative efforts of scientists from NHM and the United Kingdom's Science and Technology Facilities Council. The findings underscore the importance of innovative technologies in the preservation and study of historical specimens.

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The successful application of SORS to Darwin's specimens may pave the way for further studies on other historical collections, enhancing our understanding of preservation methods and the materials used throughout history. This could lead to improved practices in museums worldwide, ensuring the longevity and integrity of invaluable scientific collections.

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