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The tuft of hair at the end of an elephant’s tail helps as a fly swatter to protect itself from insect bites. Researchers have now found that elephant tail hair can be used to study the health of elephants.

In a paper published in a journal (PeerJ), researchers show that the tail hair can be used to assess stress in the life of the animal. The tail hair growth rate and levels of immunoreactive cortisol in hair (hC) were studied. The cortisol hormone has been previously studied in various animals to decode the ‘stressful’ past-events. Hair cortisol levels are considered to be an effective measure to understand the cumulative concentrations of systemic cortisol exposure over a longer period.

The cortisol from the blood is assumed to enter the hair through passive diffusion from capillaries. It is also speculated that cortisol produced locally or contamination through sebaceous and sweat glands may contribute to hair cortisol levels.

The tail hair samples from six captive Asian elephants from two zoos in Japan were studied and compared with the daily behavioural health records maintained by the zookeepers. The paper notes that these ‘observations open up the possibility of using the tail-hair as an alternative matrix to reconstruct the physiological history of elephants’.

The team writes that by studying these hormones and other biomarkers in hair we can assess how various captive conditions such as housing, grouping, diet, disease have affected the animal. ‘Further, analysing hair cortisol levels along with other biomarkers (such as reproductive hormones) can facilitate more meaningful biological interpretations of an animal’s life’, concludes the paper.