杏吧原创

IN MY taxi to the airport, the talk has turned to rainforests and whether cutting them down is bad. 鈥淚ts not like here in the UK, where we know everything,鈥� I say, waving at the soggy countryside. 鈥淚 work in Brazil and we don鈥檛 know what鈥檚 in many forests. Cutting them down to grow soya can be a huge loss.鈥�

That doesn鈥檛 impress the taxi driver, who left his country because of famine. I go on: 鈥淭hen there鈥檚 all the medicinal plants in rainforests. If we hadn鈥檛 explored there, who knows what we would have missed out on 鈥� a cure for cancer?鈥� This resonates. 鈥淢y uncle died from cancer 鈥� maybe your forest could have saved him,鈥� he says. 鈥淧erhaps everywhere should not be all about food.鈥�

This argument is one that tropical biologists often wheel out. If you can鈥檛 convince people with a cute or curious flagship species, or by explaining the value of forests in stopping climate change, providing new foods or securing indigenous rights, then bring on the medicinal possibilities. It rarely fails.

That鈥檚 because it鈥檚 true. Some childhood leukaemias are treatable thanks to vincristine and vinblastine, drugs deriving from the Madagascar periwinkle. And the active ingredients in curare are now used, not on blowdart tips, but in heart surgeries worldwide. Rainforest animals are also important. The skin exudates of Amazonian frogs have yielded blood pressure regulators, while venom from Asian forest scorpions and giant centipedes can help in neurological disorders.

But, as Robert Voeks says in The Ethnobotany of Eden, the real picture is a lot more complicated. Central to notions of rainforests as pharmacopoeia is what Voeks calls primitiveness, the idea that 鈥減rimitive鈥� can be equated with 鈥減urity鈥� and purity with healing. This fuels the belief that we must preserve not just any old forest but the least contaminated, most Eden-like ones.

Voeks connects this 鈥渞emote rainforest equals good鈥� argument with medieval beliefs in unicorn horn, the curative powers of which supposedly stemmed from its purity and innocence. Modern research, of course, shows that Madagascar periwinkle grows at the edges of rainforests, and that many medicinal vines come from forests disturbed by humans or by a high incidence of tree fall. Moreover, provided they are not regularly burned, 鈥渟econdary forests are just as likely to have pharmaceutically-useful plants as one shrouded in clouds, mystery, and isolation鈥�, says Voeks.

鈥淪econdary forests are as likely to have useful plants as one shrouded in clouds, mystery, and isolation鈥�

Leading fieldwork seems to confirm this. In 2013, the veteran Amazon-based medicine hunter Adrian Pohlit told New 杏吧原创 that an extract from a common roadside weed is one of his best hopes for a new antimalarial drug.

Voeks is well equipped to write a book that readjusts perceptions. An ethnobotanist at California State University, Fullerton, he has spent 30 years in tropical locations such as Brazil and Borneo. There he has studied the medical uses of plants and their origins, and how other cultures (notably European and North American) perceive them.

Voeks鈥檚 students give him good ratings online for his ability to make the complicated clear and fun. They are right. His book is full of verve and enthusiasm, and he is eclectic, erudite and humorous as he ranges from the influence of the African diaspora, as they popularise their traditional medicines in the countries they now live in, to the meaning of kids鈥� eco-protest songs.

It is always right to celebrate indigenous medicinal knowledge and mourn its loss. But Voeks鈥檚 challenge to the West鈥檚 muddled and dangerously romantic views of rainforests as phytomedical cornucopias and sources of near-mystical 鈥減urity鈥� for drugs is what singles his book out.

This article appeared in print under the headline 鈥淕et real about rainforests鈥�