Using light to describe the ancient world

Near infrared spectroscopy could be useful for detecting ancient DNA in fossil bone.

Deoxyribonucleic acid (DNA) is very rarely preserved in fossil bone. The fossil record for soft tissues is incredibly sparse, and the recovery of ancient DNA (aDNA) generally requires highly specific preservation conditions. Like most rare treasures though, the benefits of finding aDNA are immense: relationships between living and extinct groups can be established (e.g. Baker et al. 2005) and reconstructions of once living organisms can be entertained (e.g. Jurassic Park). The importance of aDNA is embodied in the Australian Centre for Ancient DNA, an entire research centre at the University of Adelaide dedicated to its study (prospective PhD students should check out this link). Finding aDNA is a difficult task, and one that would benefit from a rapid, non-destructive technique. Like near infrared spectroscopy.

Near-infrared (NIR) spectroscopy is most useful for characterising compounds constructed from light atoms, like soft tissues, which are mostly carbon, hydrogen, oxygen and nitrogen. In contrast, NIR is less adept at detecting bone mineral, which contains abundant calcium and phosphorus. This combination of these positive and negative biases makes NIR a potentially useful technique for finding aDNA. Bone mineral is essentially invisible with NIR spectroscopy, but soft tissues stand out like beacons. Ancient DNA may be found alongside collagen, the organic scaffold on which bone mineral is deposited, which is readily detectable with NIR. Further, entire surfaces of bones can be analysed with NIR using hyperspectral imaging. In essence, NIR hyperspectral imaging could be used to rapidly screen fossil bones for aDNA: surfaces of fossil bones could be mapped, allowing regions with telltale signs of preserved soft tissues to be identified.

For more detail on the prospective uses of NIR hyperspectral imaging in paleontology, check out my recent article in NIR News.

 

Thomas DB. 2011. Illuminating fossils by NIR. NIR News 22: 6-8.

Baker AJ, Huynen LJ, Haddrath O, Millar CD, Lambert DM. 2005. Reconstructing the tempo and mode of evolution in an extinct clade of birds with ancient DNA: The giant moas ofNew Zealand. Proceedings of the NationalAcademy of SciencesUSA102: 8257-8262.

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