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5 Archaeological Finds We Haven’t Explained Yet

For ages, thinkers and philosophers have pondered the question, “What makes us human?” Plato came close to answering the question when he claimed we are just “featherless bipeds.” That is until Diogenes presented Plato with a plucked chicken.

This anecdote goes to show that some things in life remain unanswered, no matter how hard we humans try to explain them. Perhaps that is a part of what makes us human: a want to explain and make sense of everything in life. The sciences have done wonders to shed light on things we previously explained away with magic or divine origins.

Archaeology is no different. We humans want to know where we came from. How did our ancestors live? What does that mean for us? But, more often than not, these ventures into ancient history saddle us with a dozen more questions for every answer they reveal. But, being human, we are hardly deterred by these mysteries. In fact, the mystery is what makes these questions so titillating.

Archaeologists have made many such discoveries. Hoping to understand our past better, we have instead found things we just simply cannot explain.

If you came here looking for answers, then you’re in the wrong place. But if you want some head-scratching mysteries to ponder while bored at work, then you’ve clicked on the right video.

Today, we’re examining the top five archaeological discoveries we haven’t explained yet.

Stone Spheres in Costa Rica

In the jungles and on the beaches of Costa Rica lie stones. Nothing special, right? Well, what if I told you that these stones date back to as early as 300 C.E. and are perfectly round? They are also located dozens of miles away from their source and are made from chunks of rock weighing more than a dozen tons.

Stone spheres in National Museum of Costa Rica
Stone spheres in National Museum of Costa Rica. By Rodtico21, is licensed under CC-BY-SA

That is pretty much all we know about these spheres. Questions abound, like who made them? Why did they make them? How did they make them? How did they transport these massive stones across thirty miles of jungle? What purpose do they serve?

If we knew the answers to these questions, then we wouldn’t be talking about them now. But experts have taken cracks at guessing. Some theories claim these stones are hand crafted while others claim they were naturally formed in the bed of the Terraba River. There is much doubt surrounding the “naturally occuring” theory since nature tends to not build in perfect spheres. Plus the fact that the Terraba River is fifty miles away from many of the sites where the stones now sit. This means ancient humans were involved in at least transporting them. There’s a good chance they altered their shape as well.

Which poses another eyebrow-furrowing mystery: how did a pre-machine civilization lug fifteen-ton stones through the untamed jungles of Costa Rica? Doing so would have meant hacking a path through thick growth for a very long time while somehow moving the weight of three T-Rexes or fifty grizzly bears. What could make them take on such an arduous task?

Theories on these stones’ purpose range from ceremonial use to religious significance to denoting tribal rank to marking burial spots. As often happens when confronted with mystery, humans have made stories and legends to try and explain.

According to some, ancient civilizations created a potion to soften stone, which enabled them to sculpt these perfect spheres. Others claim gods shot the stones down from the heavens to drive away enemies. Still others claim these stones originate from Atlantis.

Grand myths aside, science has had little more success in deciphering these stones’ mystery. Since these stones were moved from their origin point, scientists have found it hard to date them accurately; the most accurate time frame they have given is between 300 and 1500 C.E. The arrangement of the stones perplex experts, some clusters being arranged in a line, some in a curve, some just in a random cluster, and others completely alone. Certain clusters are even arranged in geometric shapes that point to Earth’s magnetic north.

For all the questions circling around these spheres, we are unlikely to find definitive answers. Whichever culture was responsible for the stone spheres’ creation was wiped out by the onset of Spanish colonizers, and they left behind no written record.


This next archaeological find sticks with the theme of gigantic South American rocks. Let’s go to the Peruvian city of Cusco, or, more accurately, north of Cusco to the ancient walled complex of Saksaywaman.

acsayhuamán, Cusco, Peru.
Sacsayhuamán, Cusco, Peru. By Diego Delso, is licensed under CC-BY-SA

This Incan construction has been the object of scholarly examination and debate solely because of its walls. You might think that walls are nothing special. I mean, people were building walls centuries before the Incas constructed Saksaywaman in the 1400s. The aspect that fascinates archaeologists, though, is the mortarless method the Incas used and how, despite nothing to bind them, the stones in the wall mesh together perfectly.

These 25- to 200-ton stones were made to fit together so well that not a gap can be seen between them. In fact, the rocks fit together so well that neither a sharp knife nor a piece of paper can fit between.

How did the Incas move such massive rocks? How did they shape them to fit together so well? How were they able to lift 200 tons into place without the modern-day convenience of cranes? Experts have wondered and scratched their heads, trying to answer these questions.

Theories abound, some educated guesses, others a bit more far-fetched. And of course, with any unexplained phenomena, the explanation of “Aliens!” has been thrown out there. Some of the more researched theories include a plant’s liquid being used to soften and shape the rocks, or heat treating them using large sun mirrors.

A more current theory put forward by retired architect and construction manager John McCauley claims the perfect fit of the walls and the gargantuan effort needed to build these walls was achieved through trial and error. Generations of Incas had hundreds of years to learn from their ancestors and perfect their method before finally erecting the finished project. As the saying goes, “Rome wasn’t built in a day;” which sounds only slightly better than “Saksaywaman wasn’t built in a day.”

These walls have stood the test of time, surviving more than half of a millennium through earthquakes, weather, colonial invasion, and now tourism.

Nazca Lines

This next archaeological wonder keeps us in Peru, but takes us up into the sky. Though the Nazca lines are drawn into the sand and dirt of the Peruvian desert, they can only be fully appreciated from high above.

These lines depict a myriad of different animals, plants, shapes, and people. These depictions are as big as 440 to 1,200 yards (400 to 1,100 meters), covering a total area of around 19 square miles (50 square kilometers), but only going 4 to 6 inches (10 to 15 cm) deep in the ground.

Aerial view of the "Monkey", one of the most popular geoglyphs of the Nazca Lines
Aerial view of the “Monkey”, one of the most popular geoglyphs of the Nazca Lines. By Diego Delso, is licensed under CC-BY-SA

The designs depicted range from geometric figures to 70 different kinds of animals and plants, including a monkey, hummingbird, spider, whale, dog, cactus, flower, and tree. Other geoglyphs are just plain old lines, swirls, and zig-zags.

Most titillating to experts and conspiracy theorists alike, though, are the depictions of humanoid figures, most notably one nicknamed “The Astronaut.” More recent archaeological expeditions have discovered depictions of what seems to be a decapitation scene and another, a picture of a many-legged, mythical creature sticking out its tongue.

Whirlwinds of questions surround these discoveries, Why did they draw this? How did they draw it? How were they able to achieve such great geometry on such a large geoglyph with no aerial help? Insert the obligatory “Aliens!” explanation here.

Experts know the Nazca culture, which thrived in the area from about 100 B.C.E. to 100 C.E., created the lines, perhaps with the help of the Chavin and Paracas cultures that came before them. What they do not agree on, though, is how they made them and why.

It’s fairly obvious that ancient peoples removed the top layers of sand and soil to expose the differently colored dirt beneath, making the lines and shapes visible. However, what experts cannot agree on is how they were able to form those lines into giant shapes. Some theories claim the ancient peoples used models, ever increasing in size and proportion, until they were able to carve out the massive geoglyphs we see today.

Another topic of debate is why the lines were carved. What purpose did they serve? Some guesses say they were related to astronomy and served a calendrical purpose. Other guess claim they were part of a ritual, a path that devotees would follow. Still others claim they were a message to the gods; shapes affiliated with water carved in the ground in one of the driest parts of the earth to illicit rain.

Whatever the actual reasons are, they elude even the most knowledgeable of experts. Suffice it to say, despite the extensive number of geoglyphs found, we still don’t have the full picture of the Nazca Lines.

The Dropa Stones

Since so many unexplained archaeological mysteries seem to be accompanied by the faint whisper of “Aliens…” drifting around on the wind, let’s give in for a minute and take a dive into one of the more bizarre, unexplained archaeological tales.

As the story goes, an archaeological expedition in Southwest China, along the border with Tibet, uncovered artificial caves housing over 700 discs. Allegedly, the discs were buried alongside the skeletons of short, frail creatures with large skulls.

Bi Disc China, Liangzhu period, 3rd Millenium BC.
Bi Disc China, Liangzhu period, 3rd Millenium BC. By Dr. Meierhofer, is licensed under CC-BY-SA

These discs had small holes in the middle and spiral grooves carved around them, almost like a record. These discs were sent to different experts and universities until they finally found a Chinese archaeologist. He claimed that the spiral grooves were actually a hieroglyphic text that told a 12,000-year-old story of the Dropa aliens who crash landed on Earth and were hunted down by the local people. Allegedly.

The story continues on to say that the discs were then shipped to Russia for further study where it was found they were made of electricity-conducting metals. After that, the discs disappear forever, until 1974, when Ernst Wegerer, an Austrian engineer, claims to have seen them in Banpo Museum in Xian, China.

The mystery unravels, though, when the facts are considered. Or should I say lack of facts. In fact, there is no record of an archaeological expedition in that area during the supposed time of discovery, the Chinese archaeologist who translated the discs has never been confirmed to have even existed, the pictures Ernst Wegerer allegedly took of the discs have never been seen, and even the discs themselves have eluded verification.

Though they make for a fascinating archaeological tale, the Dropa Stones are most likely just that. Not all mysteries can be backed by fact.

Longyou Grottoes

Returning to the realm of evidence-backed archaeological finds, let’s look at the Longyou Grottoes. This cave complex, comprising 24 independent caves, sits in the sandstone earth of Fenghuang Hill in the eastern Chinese province of Zhejiang.

These caves measure between 60 and 110 feet (18 to 34 meters) and reach as tall as 65 feet (20 meters). For a long time, the Longyou Grottoes were thought to be an odd-but-natural phenomenon. All the other human-made caves, quarries, and mines from similar time periods differed vastly from these.

Longyou Caves. By Zhangzhugang, is licensed under CC-BY-SA

The construction of these caves impressed experts. A single, vertical entrance with carved stairs leads in and out of the caves. These shafts also allow rainwater to flow into the caves where a system of drainage troughs, channels, and water traps direct and store the water.

A steel chisel was discovered in one of the larger grottoes. This led experts to theorize that the caves were formed from chiseling out the hollow interior layer by layer.

Further research has led to theories that attempt to answer the question of when were they built. Clay pots discovered in some caves date back to the Western Han Dynasty, which reigned from 206 C.E. to 24 C.E., making the caves around 2,000 years old.

The lack of further evidence makes it hard to say what purpose these caves served. That hasn’t stopped a slew of theories being proposed. It’s possible that the Longyou Grottoes were ancient quarries; or perhaps hidden military encampments; or maybe storage, reservoirs, or Taoist dwellings; or perhaps even a subterranean palace, or ceremonial site. Whatever the truth may be, it remains buried deeper than the grottoes themselves.








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