An MMA fighter was offered £370,000 to fight a chimpanzee, with warnings about catastrophic injuries.
Cole Johnson said what began as a joke became an actual bout.
The event appeared to be cancelled after its website was taken down over safety and trust.
It was subsequently labelled as a crypto hoax.
In a separate case, nine chimpanzees on Ngamba Island chose a baited box on 73 percent of trials when a human pointed, called names and made food grunts.
Pointing alone had no such effect.