It sometimes happens to come across videos of animals that smoke - usually primates hosted by a zoo, which reuse the butts abandoned by rude humans. But the puffs of smoke from another animal raise more questions: a group of biologists has recently filmed an Asian elephant female (Elephas maximus) intent on smoking pieces of coal in the middle of an Indian forest.

The pachyderm was found by scientists from the Wildlife Conservation Society's India Program while they watched the hidden cameras inside the Nagarahole National Park and Tiger Reserve, in the Indian state of Karnataka. In the video you can see the elephant collecting pieces of charcoal that are still steaming, filling its mouth and exhaling puffs of smoke.

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Sought on purpose. In many Indian forests, forest rangers use small controlled fires to create paths that help curb the fires. This technique leaves pieces of coal scattered on the ground behind, which perhaps the pachyderm has not collected by chance. For the authors of the discovery, the elephant may have used coal as a "drug", exploiting its ability to bind to toxins and its laxative effect.

"The female seemed to pick up pieces from the ground, blow away the ash accumulated on them and consume the rest, " explains Varun Goswami, biologist at the Wildlife Conservation Society. Moreover, charcoal can also be formed in places not reached by man, for example near trees struck by lightning.

Image Chimpanzees have learned to appreciate the healing qualities of some plants, and they regularly exploit them. See also: the most curious forms of self-medication among primates | Anup Shah / Nature Picture Library / contrast

eat (and smoke) that passes you. Animal self-medication - called zoopharmacognosy - can also reach very sophisticated examples: the red còlobo of Zanzibar (Piliocolobus kirkii), an endemic primate of the African archipelago, has been observed eating coal to counteract some toxic substances present in its diet. Some Congo bonobos ingest rough leaves in full, in an attempt to remove parasites from the digestive tract. Other primates eat clay to wipe out bacteria, while African elephants in Kenya use some leaves to speed up the birth.

It is not clear whether these are behaviors learned or deriving from an ancestral knowledge of the "chemistry" of the territory. This second hypothesis is certainly true for some Mexican passerines, who have learned to exploit the insecticidal properties of the nicotine contained in abandoned cigarette butts: using them to paper the nest, they keep the parasites away.