James Stewart

Because if humans lived in all those amazing sites we've showcased in this video, which does seem very likely, how did they exist in spite of the rainforest's naturally poor and nutrient-depleted soil?

How did they grow stuff?

It's impossible, right?

Remember at the start of the video, when we said all of those expeditions, right from the 1500s to poor old Percy Fawcett in 1925, all of those had scientists saying part of the reason the cities couldn't be found

was because the soil was too infertile to support human life.

Remember that?

Well, modern day science has since shown that to be wrong too, actually, but in the most shockingly brilliant way.

New research shows something surprising.

Ancient Amazonians intentionally created patches of rich, dark soil, known as terra preta or Amazonian dark earth, to make farming possible, and this was no accident.

In fact, they're still doing it today.

Modern indigenous communities like the Kwikuru still make dark, fertile soil by firstly piling up food scraps and organic waste, then spreading charcoal and ash around fields, before finally creating these compost middens.

Over time, these practices produce carbon-rich soil that thrives with nutrients, even in a region where untouched soils are typically infertile.

Try and get your head around this.

Ancient Amazonians weren't just passive forest dwellers.

They actively managed landscapes.

They created fertile ground to grow crops and support large populations, and there's another bonus too.

Because Dark Earth holds huge amounts of carbon, these practices incidentally locked carbon into the ground for centuries or even millennia.

That makes terra preta not just fertile soil, but a potentially powerful example of long-term carbon sequestration.

And that soil does way more than just help provide food.

Woven into all of this is the fact that in almost every example we've talked about in this video, the forest itself is part of the construction.