Amphibians could help cure our ills, from diabetes to fungal infections – if they don't go extinct first, says Matthew Gould.
I WAS at university in the early 1990s, when toad licking was the latest drug-related panic. I remember many conversations about it, though I don’t remember anyone actually licking a toad, or indeed any other amphibian.
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| Simone Rotella |
The nearest anyone got to real psychedelic experimentation was an architecture student called Mark, who tried to smoke banana skins. I don’t think it worked. But the toad thing hasn’t gone away. Only last year, the US National Park Service asked its visitors to stop licking toads because of the effect it was having (presumably on both the visitors and the toads).
It turns out the potential of amphibian secretions goes much further. Research presented at a recent Diabetes UK conference showed that a molecule on the surface of East Asian bullfrogs boosted insulin production in mice, which could be an important development for the 400 million people with type 2 diabetes.
This is only the latest discovery of a prospective medicine from frogs, of which there are more than 7500 species, each with its own collection of potentially useful chemicals. No two species have been found to have the same compounds on their skin.
Skin secretions from several Australian tree frogs have already been shown to inhibit HIV infection. Some work against fungal infections and others have different antimicrobial properties. A compound isolated from the phantasmal poison frog has been shown to have 200 times the painkilling potency of morphine.
Frog foam, a substance some species use to make nests, could be useful as a temporary dressing for wounds and burns. Foam from the túngara frog could help provide a slow-release delivery system for antibiotics.
But there is bad news as well. Amphibians are about the most threatened group of animals on the planet, with more than 40 per cent at risk of extinction. Some of the fastest species declines on record have been of frogs.
For more than 20 years, the Zoological Society of London, the international conservation charity I lead, has been at the forefront of amphibian disease research. In the mid-1990s, alongside partners, our scientists discovered that a chytrid fungus was devastating amphibian populations globally. We have since helped lead efforts to stop this turning into an extinction.
We have discovered that washing frogs in an antifungal bath can buy conservationists more time to implement longer-term protective measures. On Montserrat, our scientists are trialling heated pools for the critically endangered mountain chicken frog. In a nice inversion of the normal boiling frog cliché, warm water kills the fungi without harming the frogs.
Chytrid fungus is just one of the problems causing amphibian numbers to plummet. Even if we learn how to deal with its consequences, amphibian populations are still being decimated by habitat loss, pollution, invasive species and other threats, all of them arising from our own inability to live in balance with our planet.
Though we often try to separate ourselves from nature, we will always end up dealing with the consequences of upsetting its equilibrium. In Central America, for example, declining numbers of frogs have led to an increase in malaria – probably due to there being fewer frogs to act as pest control. And then there are all the potential therapies on the backs of frogs that we might never get to benefit from if they go extinct.
Protecting wildlife isn’t a luxury, it is an important part of securing our future. From the myriad benefits of frogs to the carbon-capturing impact of wildebeest and the ocean-purifying work of oysters, we need wildlife to flourish if we are to flourish. So let’s not lick any more toads, kids.
Matthew Gould is chief executive of the Zoological Society of London