Not only are there 4,000 year old termite mounds still around in the world, there are 200 million of them. They are also huge. Each mound is made up of about 1,800 cubic feet of soil. In total, 2.4 cubic miles of earth were necessary to build all of them, and if we were to convert them to a human equivalent, you would have 4,000 Great Pyramids of Giza.
All of these termite mounds are found in an area in northeastern Brazil that is similar in size to Great Britain. However, these 8 foot tall and 30 feet wide in diameter mounds are not nests. They are instead excavated dirt, which the termite species Syntermes dirus removed in order to build a sprawling network of underground tunnels.
The purpose of these tunnels was to allow easy and safe access to dead leaves on the forest floor, and the mounds remained undiscovered until very recently because the land was covered by deciduous trees. However, the land was cleared for pasture over the last few decades and the mounts were slowly revealed.
In order to study the mounds, scientists gathered samples from 11 of these structures. They found that they ranged in age from 3820 to 690 years old, dating them close to the world’s oldest known mounds in Africa. Researchers also studied the spacing between the mounds which followed a similar pattern to the mima mounds found in Washington state. The mima mounds are lumps of soil formed by either plants or gophers, depending on who you ask. The mounds found in Brazil also resemble the Namibian fairy circles and the “heuweltjies” of South Africa.
Scientists were also interested in postulating a viable theory for why the mounds were spaced the way they were. In this situation, it did not make sense that the distance between the mounds was due to conflict between different colonies, but rather due to the way the tunnels were formed.
The underground tunnel system is very complex as well, which led scientists to postulate that the termites were using a pheromone map to navigate it. The network was “designed” to give the termites a safe route to sporadic food supplies, a similar feature that is often seen in naked mole rat tunnels.
To think that you can still find a biological wonder of this magnitude that was completely unknown just a few decades ago is very exciting. The sheer strangeness of it, both in terms of appearance and age is truly impressive. It’s worth noting here that the mounds have no internal structure, and seemingly no purpose. They only exist as “dumps” of soil material that the termites excavated over thousands of years while building their tunnels.