You look in vain in the rainforest for most of the archaeological clues that we take for granted in Europe. You can’t date anything by dendrochronology - tree rings - because nothing timber survives. There are no food remnants, no scraps of cloth, no ruined buildings. But what it left, apart from mystery, is very valuable indeed: a lesson in how to manage the rainforest itself.

It is now clear that the Amazon, when it supported such a relatively teeming population, was not some undisturbed tropical paradise. It was managed - farmed. It was, however, not a monoculture. Once you develop a nose for the Black Earth, I’m told you start to notice other signs - like a slightly different arrangement and concentration of the trees, which suggests that the original inhabitants were planting and nurturing particular species rather than just sucking dry one bit of forest and then moving on to the next.

This was a bigger, more advanced civilization than you would ever think from a study of the sadly dispersed and isolated remaining indigenous Indians in the furthest-flung corners of Amazonia - who still lose out every time they make contact with the rough stormtroopers of Western trade. It is frustrating: this forest civilization was there and fully operational, even as the European conquerors arrived: but it had gone, long before anyone thought to stop and consider what it was or how it operated.

In those days, we Europeans thought the forest went on for ever and would last for ever. Today, as the slashing and burning continues, we know differently. Possibly, what Eduardo Neves and his merry band of archaeologists is doing now may open our eyes to a different way of doing things. Or then again, it may already be too late.