What Happened to the World's Greatest Ape?

If you were to walk through the forests of Southeast Asia during the Ice Age, you would probably see many amazing and familiar creatures, such as rhinos, tapirs, and hyenas. But once an animal roamed these woods and it was like nothing you've ever seen. At about 3 meters tall and weighing up to 500 kilograms, this beast was probably twice the size of a modern gorilla. Scientists call it Gigantopithecus, the largest great ape that ever lived. And for us primates, there are some important lessons to learn about how it lived and why it disappeared. So the story of Gigantopithecus begins with some of the smallest physical clues: teeth.

And they were not found in the countryside, but in a pharmacy. In 1935, paleontologist Ralph von Koenigswald was rummaging through the pharmacies of Hong Kong. He was looking for so-called dragon teeth, the name given to the fossil teeth of all types of animals that were used in traditional Chinese medicine. And on one of these trips, von Koenigswald found a molar like he had never seen before. The tooth was like that of an ape, wide and flat, but it was much larger than any known species, living or extinct. Von Koenigswald eventually determined that these teeth were from a huge primate and he named this new creature Gigantopithecus, or "giant ape." After this initial discovery, more teeth were found in other medicine stores and eventually some fossil jaws were found in a Chinese cave.

But that was all. Since then, we have found more jaws and thousands of teeth. But no other part of the giant ape's body has ever been discovered. Although we have very little of its anatomy to study, we have managed to discover a lot about Gigantopithecus just from those teeth and jaws. To begin with, it turns out that there were three species of this giant ape, the oldest of which dates back to about 9 million years ago, in the Miocene epoch. But the most recent, and by far the largest of them, was Gigantopithecus blacki. It lived between 2 million and 100 thousand years ago, during the Pleistocene epoch, in

what

is now southern China and Vietnam.

Of course, the most obvious feature of Gigantopithecus blacki's teeth is their size. At 2 and a half centimeters wide, the ape's molars were more than twice the width of a human tooth. But an even closer look at these teeth has revealed much more than just the size of this animal. On the one hand, scientists have been able to use them to discover who their closest living relatives are. In 2008, a team of anthropologists studied the thickness of the enamel of ten Gigantopithecus teeth, as well as the shape of the hard tissue underneath, called dentin. They found that the structure and composition of the fossil teeth were very similar to those of the only great apes left in Asia: orangutans.

Which is... kind of strange. Because orangutans are arboreal; They spend most of their time high in the trees. But Gigantopithecus was too big to do that. So, scientists believe that it must have been an inhabitant of the earth. Which raises a new set of questions. On the one hand,

what

does a 500-kilogram primate eat? Well, their teeth were flat and wide, but their jaws were deep and strong, and all of these characteristics are associated with eating tough, fibrous plants. Some microscopic fossil plant teeth, called phytoliths, have also been recovered, showing that they fed on grasses, possibly including bamboo, as well as seeds and fruits.

But while these physical clues can tell us a lot about this extinct ape's diet, the chemical makeup of its teeth can also reveal where it lived. And possibly why it disappeared. The trail of clues here begins with carbon isotopes. Different types of plants produce different ratios of carbon isotopes during photosynthesis, depending on the type of environment in which they live. For example, plants that live in cold, wet climates are typically what are known as C3 plants, because their way of photosynthesis results in a 3-carbon acid that has its own unique combination of carbon isotopes. But plants that grow in hotter, drier climates are usually C4, because they photosynthesize in a slightly different way and produce their own byproducts with their own carbon ratios.

And all of this is extremely useful to scientists, because the chemical signatures of these plants are absorbed by the animals that eat them. So by studying the chemistry of Gigantopithecus' teeth, researchers can tell not only what kind of food it ate, but also possibly what its Ice Age habitat was like. And in 2011, paleontologists in China studied the tooth enamel of Gigantopithecus and found that it fed exclusively on C3 plants, which tend to grow in cool, moist forests rather than warm, grassy plains. At the same time, however, fossils of other mammals that lived alongside the ape have also been studied: I am referring to the rhinos, tapirs and hyenas that I mentioned before.

And it turns out that they ate some C3 plants, but also C4 plants, which grow in drier grassy areas. So this suggests that Gigantopithecus probably lived in a mosaic habitat, something like a checkerboard of forests and grasslands. But unlike its fellow herbivores, Gigantopithecus preferred to live only under the dense forest canopy and did not go out into the open, much like modern orangutans and mountain gorillas, which are also forest experts. And this specialized lifestyle seemed to work very well, at least for a while. The fossil record shows that Gigantopithecus blacki existed for almost 2 million years in the forests of Southeast Asia.

But these primates lived during a time of great change. The Pleistocene is sometimes called the Ice Age, when glaciers constantly ebbed and flowed across the land, retaining moisture when they froze and releasing it again when they thawed. This constant fluctuation meant that Pleistocene habitats were in a state of flux. Things could be warm and wet for 20,000 or 100,000 years or so, allowing forests to grow. But then it would freeze again and carry all the moisture to higher latitudes, and grasslands would spread. Somehow, Gigantopithecus managed to survive the first of these glacial periods, but 100 thousand years ago, in the Middle Pleistocene, something changed.

Another cold snap occurred that was simply too severe for the apes to survive. As the ice expanded, so did the grasslands, shrinking Southeast Asia's forests. Without the habitat it needed to survive, Gigantopithecus populations declined dramatically. And 100,000 years ago, the last Gigantopithecus had disappeared. So Gigantopithecus managed to thrive for so long because it was a specialist: it found the right combination of food and habitat to meet its probably enormous needs. But in the end, his specialized habits left him vulnerable in an ever-changing

world

. And in this sense, their situation is similar to that of many modern animals, including their closest living relatives, orangutans.

Orangutans are also forest specialists and are only found in the dense jungles of Borneo and Sumatra. But for decades their unique forest homes have been reduced by things like logging and wildfires. With much of their habitat gone, all three orangutan species are now considered critically endangered. Still, some researchers remain hopeful that we can help these distant cousins ​​of Gigantopithecus... and us! - by continuing to learn the story of the largest ape that has ever existed. Now, what do you want to know about the history of life on Earth? Let us know in the comments. And don't forget to go to youtube.com/eons and subscribe!

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