by diseases like the common cold to which they have no resistance. According to Miriam Ross of Survival International, which campaigns to protect the world's remaining indigenous peoples, 'These tribes represent the incredible diversity of humankind. Unless we want to condemn yet more of the earth's peoples to extinction, we must respect their choice. Any contact they have with outsiders must happen in their own time and on their own terms.' As to who these people are, how they live their lives, what language they speak - we know nothing. 'Normally you can tell who tribes are by their language, how they wear their hair, how they adorn their bodies and so on, but in this case the photos don't allow us to get close enough to see,' says Ms Ross. Hidden homes: The tribe's tent-shaped dwellings deep in the rainforest When anthropologists first overflew the area, they saw women and children in the open and no one appeared to be painted. It was only when the plane returned a few hours later that they saw these individuals covered head-to-toe in red. 'Tribes in the Amazon paint themselves for all kinds of different reasons - one of which includes when they feel threatened or are aggressive,' Ms Ross says. 'And they are almost certain to feel threatened by or aggressive towards a plane, which was where the photos were taken from. They are almost certain not to understand what the plane is - perhaps a spirit or a large bird.