LONDON: The field researcher watching a couple of chimpanzees in Gombe national park in Tanzania noticed something odd. One of them, known as Hugo, had left the path and started picking at the leaves of a plant called Aspilia rudis. The shrub was not part of chimpanzees’ usual diet, unsurprisingly since its leaves are rough, sharp and extremely nasty to eat. Yet Hugo had not only sought it out but he had also eaten the leaves in a particular way, carefully folding them up concertina-style and holding them briefly in his mouth before swallowing. From the way he was grimacing, it looked just as if he was taking an old-fashioned medicine.

That observation in 1972 was to lead to a whole new way of thinking about animals and their health. At the time the notion that animals might be deliberately treating themselves with natural medicines was beyond the scientific pale. It is true there was no shortage of anecdotes about animals using herbs to cure themselves, cultures as far apart as China and ancient Rome have them and all pet owners know about cats and dog eating grass when they’re sick. But until very recently, scientists dismissed such reports as romantic anthropomorphism.

But, gradually, the researchers in the Gombe began to gather evidence to show that something very deliberate was going on. They found that Aspilia leaves were used by local herbalists for stomach upsets and that they contained chemicals which were both antibacterial and attacked gut parasites. What is more, other chimps were seen occasionally eating from 19 other plants that also had rough leaves, in the same way. The leaves were excreted whole and, when examined closely, tiny nodular worms that infect the gut could be seen wriggling on the barbs on the leaf surface.

This is just one of dozens of examples of animals actively taking care of their health featured in a fascinating new book, Wild Health: How Animals Keep Themselves Well and What We Can Learn From Them. Far from self-medication being romantic nonsense, author Cindy Engel, of the Open University, shows that most animals routinely use a variety of techniques to deal with injury, infection, parasites and biting insects.

They use plants, earth and even insects in ways that are not just about getting energy or nutrients but are specifically aimed at keeping themselves and their offspring healthy. The implications are huge. Not just for how we should look after domestic and farm animals but for what we need to stay healthy ourselves.

Just as we do not usually take aspirins unless we have a headache, so animals tend to avoid medicinal plants unless they need them. At the Awash falls in Ethiopia, for example, there are two baboon populations, one above and one below.

The tree Balanites aegyptiaca, the fruit of which is used by the locals as a de-worming treatment, grows in both areas. But it is only the lower baboons, which are exposed to a parasite spread by water snails, eat it.

But plants are not the only source of medicinal substances. There is a cave on the side of Mount Elgon, an extinct volcano in western Kenya, which has been mined by generations of elephants. It is estimated they have taken five million litres of rock in the last two million years.

Access to it is tricky, but the animals are willing to risk death to get there. The bones of those who did not make it line the trail. Once inside they dig out the soft rock with their tusks, grind it with their teeth and then swallow it.—Dawn/The Guardian News Service.