However, during the wet season, the Amazon and its tributaries burst their banks and spread across the landscape. The zig-zag ridges, built up with vegetation, rocks and even basketwork, would have made effective fish weirs, yielding enough protein to support a substantial population. The zig-zags would also have hindered water from draining back into the rivers at the end of the rains, creating ponds that could have been exploited well into the dry season. Today, savannah ponds associated with the zig-zag ridges may last all year round. They teem with fish and edible snails, and the oasis-like surroundings encourage the growth of palm trees.
Palms yield nutritious fruits as well as timber and fibre.
Even rotting palm logs have uses, as nurseries for protein-rich grubs of the palm beetle. The ponds and associated vegetation would have been magnets for a variety of game. So rather than going hunting, the fish-trapping Amazonians let the wildlife come to them. To the western eye, it looks lush and natural. The reality is rather different.