Laser scans are intended to detect illegally traded ivory

Elephant and mammoth tusk samples

Elephant and mammoth tusk samples. © Ben Booth

Despite an international ban, poachers continue to hunt elephants to get their tusks. The ivory trade is illegal but lucrative. But how can customs prove whether the ivory comes from an elephant or a long-extinct mammoth whose trade is legal? A research team has now developed a new laser technology that can quickly and reliably determine the origin of tusks. This means poachers can no longer pass off elephant ivory as mammoth.

The Convention on International Trade in Endangered Species (CITES) prohibits the trade in ivory from elephant tusks, as well as the killing of the animals. But the illegal trade continues and poachers continue to hunt elephants to get their tusks. As a result, the global elephant population is declining by around eight percent every year. According to estimates, there were only around 410,000 elephants left in Africa in 2016. As a result, some elephant species are endangered or threatened with extinction.

However, the trade in old ivory made from mammoth tusks is permitted because this species has long been extinct and can no longer be preserved. Because mammoth ivory is valuable and lucrative but rare, poachers often declare elephant ivory as mammoth. Both consist of cementum, tooth enamel and, above all, dentin, a mineralized connective tissue made of collagen and crystalline calcium phosphate minerals. It is difficult for customs officials to see the difference with the naked eye. “The complete tusks of elephants and mammoths look very different, but when the ivory is cut into small pieces, it can be virtually impossible to distinguish elephant ivory from well-preserved mammoth ivory,” explains Alice Roberts from the University of Birmingham . The objects are particularly difficult to tell apart if the ivory has already been processed – for example for carvings.

An intricately carved ivory figure under the microscope in an inVia Raman microspectrometer
A figurine made of ivory, believed to have come from an Asian elephant, under the microscope in an inVia Raman microspectrometer. © Dr Rebecca Shepherd

Laser scanning makes it easier to distinguish the ivory

A research team led by Roberts and first author Rebecca Shepherd from the University of Bristol has now developed a method that can distinguish elephant and mammoth ivory better than previous techniques. To do this, they used the laser-based technology of Raman spectroscopy, which is already used to identify bones and minerals. A sample is irradiated with high-energy light in order to examine the chemical composition of the material using molecular vibrations and light scattering. For their tests, Shepherd and her colleagues analyzed eleven ivory samples from the Natural History Museum in London. They came from mammoths and African and Asian elephants.

The laser analyzes provided a reliable classification of the ivory – based, among other things, on its crystal maturity and the content of phosphate, carbonate and collagen, as the team reports. “The methods recommended to date by the United Nations Office on Drugs and Crime for assessing the legality of ivory are predominantly expensive, destructive and time-consuming techniques,” Shepherd said. These include radiocarbon dating and DNA analysis. The laser scans, however, do not damage the samples, only take a few minutes and are comparatively inexpensive, according to the team. “Raman spectroscopy can provide results quickly and is easier to use than current methods. “This makes it easier to distinguish between illegal elephant ivory and legal mammoth tusk ivory,” says Shepherd.

New weapon in the fight against poaching and illegal trafficking

According to the researchers, customs authorities around the world should now use this technology and inspect more ivory items. This would expose illegal traders and at the same time deter poachers and thus protect the elephants. “By providing a quick and easy alternative to current methods, the use of Raman spectroscopy could play an important role in combating the illegal ivory trade,” says Charlotte Deane from the British Engineering and Physical Sciences Research Council (EPSRC), which funds physics research.

At the same time, the technology could also help archaeologists identify fossils. This could potentially also make it possible to determine the age of mammoths or their diet, as Shepherd and her colleagues report. To do this, however, additional ivory samples would first have to be scanned in order to differentiate the chemical profile of the tusks in detail according to species, age, gender and habitat.

Source: University of Bristol; Specialist article: PLOS ONE, doi: 10.1371/journal.pone.0299689

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