Elephants use their sense of smell to help identify explosives in soil samples
The impact of war on local wildlife can be devastating, the effects of which are often felt well beyond the initial threat. In areas where wildlife experience unrestricted moment through previously affected zones, unexploded landmines present a significant and potentially lethal problem. Anecdotal reports of African elephants avoiding minefields together with telemetry data suggest that the species may be able to detect concealed land mines using olfaction (sense of smell).
Trinitrotoluene (TNT) is the most commonly used explosive component of landmines, it is not highly volatile, making its detection, using olfaction, difficult. Contributing to this, anti-personnel and anti-tank mines are typically buried down to maximum depths of 50 and 150mm respectively, making it even harder to detect.
African elephant possess the most olfactory receptors (OR) of any mammal testes (~2000). Both dogs and rodents (mice and rate) possess fewer OR genes (~811 and ~1200 respectively). This high number of OR genes in elephants suggests that the species may have a superior olfactory ability to discriminate between structurally similar scents thereby potentially increasing their olfactory resolution. Along with their problem solving abilities, memory retention and cognition function may contribute significant advantages in scenarios such as crossing landmine-affected areas.
In our work with the US Army it was demonstrated that African elephants can detect TNT using olfaction, and that they can be trained to communicate its presence reliably and repeatedly. It was also shown that elephants have high capacity to distinguish TNT from other strong volatiles such as ace-tone, household bleach, and unleaded petrol. Indeed, the species shows great potential for playing an important role in landmine detection.
At no point does the US Army nor Adventures with Elephants, advicate on-site use of elephants for land-mine clearance, but see their role in scenarios where samples may be brought to them for screening. Samples collected by means of Remote Explosive Scent Tracing by mine-protected or unmanned vehicles, and screened by trained elephants could serve as the first line of investigation.