Ancient Termite Metropolis Uncovered

23 November 2018

4,000-year-old termite mounds covering an area the size of Great Britain have been found in the Brazilian rainforest...

When we think of the ancient wonders of the world, we might picture the pyramids of Egypt or Stonehenge - certainly something built by humans in years gone by. But scientists have recently uncovered millions of termite mounds in a forest in Brazil, some of which are thousands of years old.

Termites are small, ant-like insects with a reputation for munching down on wooden houses, but they are also prolific miners. They tunnel underground to create a network of passages, which allows them to safely forage for plant material - like leaves and logs - aboveground.

So, as discoverer Professor Stephen Martin, from the University of Salford, explains, “they have to get rid of the soil somewhere, just like miners. Miners build slag heaps of waste stone, and the termites have done the same thing with soil”. This process of waste removal leads to the formation of large structures above ground called termite mounds.

Martin was in Brazil collecting bees when he came across a huge collection of these mounds: “It was strange, there were so many you wouldn’t think these were actually built by an animal”. The mounds are 2.5 metres high, 9 metres wide, and spaced about 20 metres apart. “The total area we’ve estimated that they cover is about the size of Great Britain!”

The mounds have evaded detection for so long thanks to the forest canopy covering their tops.

After a fortuitous meeting with fellow researcher Roy Funch “in a swimming-hole in a river”, Martin discovered that Funch was also interested in the termites and, together, they set about analysing the mounds. They found that, not only are they incredibly numerous, but some are approximately 4,000 years old - putting them at just 500 years younger than the average Egyptian pyramid. The pair have published their findings in the journal Current Biology.

But the really special thing about these mounds, Martin says, is the way they are almost systematically arranged in an organised pattern, with one mound every 20 metres. The termites build their mounds in this way because it’s the most efficient way of excavating the waste they create while tunnelling. “It’s just a wonder of science,” exclaims Martin.

The other really unusual feature of the mounds is that some are still inhabited by their termite architects. When scientists have found fossilised mounds in the past there have been debates about whether they were really built by termites or were caused by a geological event. These populated mounds put that controversy to rest. “The formation of regular patterns in nature: it’s actually quite rare to see that process occurring,” says Martin.

Many unanswered questions remain though, including how many years it takes to build a single mound of this size. And, as Martin says, “the big goal would be to actually find the royal chamber.”

As social insects, termites live in colonies of mostly sterile male and female workers, with just a few ‘Kings’ and ‘Queens’ that are fertile. There are likely thousands of different colonies living under these mounds, and finding a few royal chambers would allow researchers to use genetics to estimate how long ago the separate colonies diverged.

“We think we’re the dominant life force actually on the planet, but in fact, we’re not,” concludes Martin. “They’re a very dominant force, the social insects. They’ve been here longer than we have and they’ll probably still be here long after we’re gone...”

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