Using Raman Spectroscopy to Distinguish Elephant and Mammoth Ivory

Researchers from the University of Bristol demonstrated that Raman spectroscopy could be used to combat the illegal ivory trade by distinguishing between mammoth and elephant ivory, according to a recent study published in PloS One (1).

The illegal ivory trade has been primarily responsible for the dramatic depletion of endangered elephant populations in Africa and Asia. Ivory is used in many products humans regularly consume and purchase, including jewelry and religious art objects (2). African elephants, in particular, have been hit hard by this illegal trade. According to National Geographic, there were approximately 26 million African elephants in 1800. Today, the African elephant is an endangered species, with only approximately one million remaining (2).

To understand the origin of the ivory trade, it is important to examine what ivory is and why the ivory trade emerged from the start. Ivory is the hard material that comes from the tusks of the teeth of elephants, narwhals, warthogs, and other animals (3). Elephant ivory is considered to be an extremely useful resource because of its beauty and durability. As a result, it is considered a luxury material, hence why the feverish demand for it (3). Because this resource only comes from a few animals, its prevalence is finite, which also increases its value (3). Ivory was first used by poachers to make tools, weapons, and works of art, but since that time, its versatility has allowed poachers and others to mass produce objects such as jewelry, piano keys, and billiard balls (3).

Realizing that the dramatic decline of elephants could upset the African savannah and its ecosystem, a worldwide ban on the sale of ivory was implemented in 1989, which led to a rebound in the African elephant population (2). However, in 1999 and 2008, the Convention on International Trade in Endangered Species (CITES) allowed two sanctioned sales of ivory, which has stymied attempts at preventing the massacre of these animals in Africa and Asia (2).

This study, led by Rebecca F. Shepherd from the University of Bristol, examined how Raman spectroscopy can help in species identification of ivory. For their study, Shepherd and her team examined elephant and mammoth ivory. The key challenge lies in distinguishing between ivory from extinct mammoths and that from living elephants, as both share similar chemical compositions (2).

The study, conducted in collaboration with the Natural History Museum in London, United Kingdom, utilized Raman spectroscopy, a non-invasive laser-based technique commonly employed in bone and mineral chemistry studies (2). By analyzing the biochemical properties of ivory, researchers aimed to discern unique signatures indicative of mammoth or elephant origin (2).

The study primarily focused on examining three types of ivory samples. The specimens included Mammuthus primigenius (woolly mammoth), Loxodonta species (African elephants), and Elephas maximus (Asian elephants). Once the Raman spectral data was collected, the researchers analyzed it using principal component analysis (PCA), which helped them discern between the different animal species through their chemical composition (2).

The findings unveiled distinct patterns in peak intensity ratios of phosphate to amide I and III peaks, as well as carbonate to phosphate peaks, underscoring the efficacy of Raman spectroscopy in species discrimination (2). Moreover, the analysis of crystal maturity indicated notable variations, with mammoth ivory exhibiting higher levels compared to its elephant counterparts (2).

As a result, the study conducted by Shepherd reveals an important, pressing concern regarding ivory identification (ID), while proving that Raman spectroscopy can provide a rapid ID method. By enhancing the identification of ivory, Raman spectroscopy can be used by law enforcement agencies and conservationists to bolster efforts to combat illegal trade (2).

The global elephant population is under persistent threat from illicit actors. Apart from working with governments to shut down open elephant ivory markets, the utilization of innovative technologies offers a glimmer of hope in safeguarding elephants from poaching and illicit trade (4).

References

(1) Shepherd, R. F.; Lister, A. M.; Roberts, A. M.; et al. Discrimination of Ivory From Extant and Extinct Elephant Species Using Raman Spectroscopy: A Potential Non-Destructive Technique for Combating Illegal Wildlife Trade. PloS One 2024, ASAP. DOI: 10.1371/journal.pone.0299689

(2) National Geographic, The History of the Ivory Trade. Available at: https://education.nationalgeographic.org/resource/history-ivory-trade/ (accessed 04-30-2024).

(3) National Museum of African Art, Ivory: Significance and Protection. Available at: https://africa.si.edu/research/conservation/protect-ivory/ (accessed 04-30-2024).

(4) World Wildlife Fund, Stopping Elephant Ivory Demand. Available at: https://www.worldwildlife.org/initiatives/stopping-elephant-ivory-demand (accessed 04-30-2024).