taking the drug.

Researchers therefore conducted tests for years longer, showing in rats that gossypol doesn't just stop sperm moving, but also damages the lining of epididymis ducts, which store sperm made by the testicles. Eventually, an October 1986 symposium in Wuhan, China – whose sponsors included the Chinese government and the World Health Organization (WHO) – concluded that gossypol was "of little interest".

"You may call it a problem, but we saw it as a solution," Coutinho tells me. He felt that the fact it could be irreversible made gossypol a potential alternative to surgical vasectomy. He joined with an international team of scientists to conduct further trials, the last of whose results were published in 2000. They found no problems with potassium, putting the effects seen in Chinadown to poor diet.

The researchers therefore applied to the Brazilian government for permission to sell the drug, needing to overcome the strong influence of the Roman Catholic Church, which forbids artificial contraception. On 14 June 2001, Josimar Henrique da Silva, founder of the Brazilian drug company Hebron, which was hoping to commercialize gossypol, wrote to Coutinho. "I'm working at the Ministry of Health in such a way as not to create more obstacles," Coutinho reads from the letter. "I can't fight against them. Give me two more weeks."

Coutinho never heard from da Silva again. The gossypol contraceptive saga ended in failure after more than three decades. Coutinho mischievously suggests Ministry machismo may have been a contributing factor. "We worked on this for many years and realized men are