A naturalist has recalled how his friend was killed in a chilling encounter with a remote Amazon tribe – who used a startling tactic to corner them. US conservationist Paul Rosolie , who has spent more than 20 years in the Amazon, recently spoke to Dragons' Den star Steven Bartlett about the deadly jungle encounter. In a " world first" last month, Paul shared stunning HD video of an uncontacted tribe in an undisclosed part of Peru , pointing out that earlier sightings had been limited to "