The oldest, biggest structure on Earth

When we think of the ancient wonders of the world, Egyptian pyramids or ancient constructions like Stonehenge often spring to mind. But this week scientists announced the discovery of one of the largest, oldest structures on the planet; it’s the same size as Great Britain. But, incredibly, it wasn’t built by humans - something much smaller did this. And Eva Higginbotham heard what from Salford University’s Stephen Martin who initially went looking for something quite different...

斯蒂芬-所以我们在布拉兹il collecting bees and suddenly these mounds started to appear and they're incredibly numerous and they're everywhere. Normally with termites, they're constructed of soil and saliva but in the Brazilian population that we've studied they're just waste. They're tunneling underground, making huge tunnels, a massive network and they have to get rid of the soil somewhere just like miners. And so miners build slag heaps of waste stone and so the termites have done the same thing with soil and they've just deposited all the soil above ground.

Eva - How big are these mounds and how much space do they take up? How big an area are we talking?

Stephen - First of all there are about two to four metres high and they're about nine meters across. So they are large. There is a mound about every 20 meters. In fact they're incredibly numerous. There are millions of mounds all in one area. The total area we’ve estimated that they cover is about the size of Great Britain, which is a vast area for any species to build anything.

Eva - Amazing! How have we managed to miss these mounds so far? How can it be 2018 and we've only just found this area the size of Great Britain?

Stephen - Well, they’re hard to miss if you're in the area. The reason they haven't been found is that they live within the forest, because the forest produces the dead leaves which is what they feed off. The forest is just slightly higher than the mounds. And so even when the leaves have gone, the forest is so dense and thorny. You can't actually see the mounds. It's just been one of these things where there are very large areas still on this planet where scientist don’t go and study.

Eva - And so what's so special about these mounds.

Stephen - What's special is the insects still live underneath the mounds in the ground and the mounds are about 4000 years old. We think we’re the dominant life force on the planet, in fact we’re not. The biomass social insects, that’s ants and termites and some bees and wasps, are actually far greater than all of vertebrates. Dogs, cats, people, elephants. The big difference is you never get to see them because most of them live in the ground or up in the trees. And here is a really stark example of the activities of a social insect that lives in the ground but you can see their activities above it. And as people we've never created a single structure or city anywhere near the size of these. So they're a very dominant force. The social insects have been here long before we have and they'll probably be still be here long after we are gone.