When Hobbits Were Real

We would like to thank Raycon wireless headphones for supporting PBS. In October 2004, our understanding of the human family tree was turned upside down. That's

when

anthropologists reported that they had discovered the bones of a small, unknown hominid on the Indonesian island of Flores. This small creature was only three feet tall and had a brain the size of a chimpanzee. But that wasn't what was so shocking. We already knew of the existence of small-bodied, small-brained hominids in the human fossil record, such as the australopithecines. The

real

ly surprising thing about this skeleton is that, at least at first, it did not appear to have been very old and yet it had characteristics of much older and more basal hominids.

The original description of the bones dated them between 35,000 and 14,000 years ago, which means they would have lived at the same time as us. But the last time a hominid with such a small brain existed was millions of years ago, not thousands, long before modern Homo sapiens appeared on the scene. And the rest of his skeleton was equally disconcerting. His shoulder joint did not resemble that of any modern human. It had short clavicles, which meant that the shoulders were turned forward in a way that had not been seen since the earliest specimens of Homo erectus, from about 1.6 million years ago.

The three bones of his wrist that were found also had a strangely archaic appearance. They were shaped like the bones of African apes and australopithecines, not like ours. And his feet were

real

ly long compared to the length of his legs. We are talking about simian proportions, not human. And yet he had short big toes and was probably an effective bipedal walker. His discoverers named this puzzling hominid Homo floresiensis, but he is often called "the hobbit" for his short stature and oddly proportioned feet. And since then he has been at the center of a major controversy in the field.

It's been fifteen years since his discovery was first announced and we're still exploring what this little hobbit can tell us about the shape of the human family tree and what it means for our own evolutionary history. And the questions this little creature raises are big: Was it its own species? Or was it really just one of us? Or could it even have descended from an entire lineage of hominids that we don't even know about? The partial skeleton that started the whole controversy is called LB1. And it belonged to an adult female Homo floresiensis, due to the shape of her pelvis and the fact that her wisdom teeth had emerged.

But he is not the only hobbit that anthropologists have found. Since its discovery, the remains of 11 other members of its species have been recovered, although LB1 remains the only one with a skull. And all these

hobbits

come from a single site: a limestone cave called Liang Bua, located in the western part of the island of Flores. So

when

LB1 was discovered in 2003, one of the first things scientists had to figure out was how to explain its small size and strange combination of features. What branch of our family tree could have produced such a strange hominid? A hominid, by the way, is a primate that is more closely related to us than to chimpanzees.

The team suggested that their species had evolved from a population of Homo erectus that became isolated on the island of Flores. And then, thanks to evolutionary pressures, their bodies became smaller over time. Now, there are Homo erectus fossils from other Indonesian islands, and they cover a wide range of time: from 1.6 million years ago to just 143,000 years ago. So we know that Homo erectus arrived in that part of the world. And we know that the body size of mammals on islands can change dramatically over time, thanks to a phenomenon known as Foster's rule, which we've talked about before.

This rule says that large mammals on islands often become smaller, and small mammals tend to grow larger, as they adapt to limited resources and fewer predators. So, in the original paper about the hobbit discovery, researchers proposed that a group of Homo erectus somehow got stuck on Flores and eventually evolved into a new species: the smaller Homo floresiensis. And Flores wouldn't have been a terrible place to be stranded. Today it is a forested tropical island and appears to have been quite similar, although more variable, while Homo floresiensis existed. It is now unclear whether

hobbits

actually lived in the cave where their remains were found.

But, based on the number of animal bones and stone tools found in different layers of the site, they appear to have used the cave more when the environment was wetter and less when it was drier and less forested. And the hobbits seem to have had a rather... exotic diet, at least by our standards. Animal remains found in the cave include many very young pygmy Stegodon, a relative of the elephant that, like hobbits, appears to have evolved into a smaller version of its continental cousins. Several of these bones have cut marks and some are even burned, so Homo floresiensis appears to have been able to use fire.

And there were also many bones from Komodo dragons, which are still formidable predators today. It is unclear whether the hobbits were hunting the Komodo dragons or simply scavenging them, but it is possible that the hobbits were hunted by the dragons! Interestingly, there do not appear to be any bones of adult pygmy Stegodon in the cave, suggesting that the hobbits may not have been able to take down an adult elephant. The hobbits also left a number of simple stone tools, such as cores, flakes and points, some of which appear to have been used not only for hunting, but also for processing plant materials.

But other experts were not convinced that these artifacts had been made by a new species of hominid. Instead, they thought that the so-called hobbits were actually modern Homo sapiens, but from a population of very small-bodied people, like some tropical hunter-gatherer groups today. And, they argued, LB1 probably had some kind of pathological condition. To support their case, these researchers compared the bones of LB1 with the skeletons of several indigenous peoples of Indonesia and Australia. His thinking was that the best populations to compare them with would be those that lived in the same region and environments as the hobbit.

And, they said, more than 140 features of LB1's skull matched those of modern humans in the area. But researchers who thought Homo floresiensis was a new species countered this argument. They said there are several groups of people around the world who have adapted to their environments by becoming smaller, but none of them ended up with the same tiny brain and strange limb proportions as the hobbit. So that only left the claim that LB1 was an individual with some kind of pathological condition. In a series of papers, supporters of this hypothesis proposed a number of different conditions that could explain LB1's very small skull, short stature, and other characteristics.

These included Laron syndrome, which is caused by an insensitivity to certain growth hormones, as well as microcephaly (having a much smaller than average head circumference) and Down syndrome. And each time, scientists who thought Homo floresiensis was a new species pointed out that none of the proposed disorders matched LB1's anatomy. Additionally, they did not explain all of the hobbit's features that resembled those of older hominids, such as his archaic-looking wrist bones. The two sides went back and forth, publishing article after article, questioning each other's arguments, and not always in civil terms. And although a group of researchers still think that LB1 is a pathological modern human, some recent work has suggested a third theory for the origin of hobbits.

The Shire! It is not a joke. Rather than being a dwarf version of Homo erectus, or a modern human with a developmental disorder, perhaps the hobbit actually evolved from another earlier hominid species, one we don't yet know about. In this scenario, Homo floresiensis is still its own new species, but its ancestor was not Homo erectus. And in 2017, some experts put this hypothesis to the test. They collected a large amount of skeletal data from 11 different hominid species and built two types of evolutionary trees that showed how the species might be related. One tree was designed around the notion of parsimony, the idea that the easiest path for one species to diverge into another is the one with the least changes in its characteristics.

The other model was built using statistics, analyzing how likely a path could be, based on different models of evolutionary change. And both methods gave quite similar results. In one scenario, Homo floresiensis shared a common ancestor with Homo habilis, a hominid that lived in Africa between 2.4 and 1.4 million years ago. In the other scenario, hobbits are part of the sister group of the branch that includes Homo habilis, Homo erectus, and us. What all this suggests is that Homo erectus might not have been the first hominid to leave Africa, although that is what the current fossil record shows. It also suggests that there are probably many ancestors on the branch of the hobbit family tree who are still out there, waiting to be found.

Which is amazing to even think about: there are so many things we don't know! Now, where is the debate about the hobbit today? Well, the consensus among most experts is that Homo floresiensis is probably its own unique species. This was helped by the publication of revised dates for the bones and stone artifacts found in the cave. Instead of dating between 35,000 and 14,000 years ago, as we initially thought, the deposit from which the skeleton came was more likely between 100,000 and 60,000 years old. And the stone artifacts were between 190,000 and 50,000 years old. So the strange little skeleton was older than we originally thought, making its archaic-looking anatomy somewhat easier to understand.

And it appears that there were changes in the island's climate and volcanic eruptions about 50,000 years ago, which could explain why the species disappeared. But from whom it descends remains an open question. And the more we dig into Southeast Asia, the more complicated our evolutionary history appears to be. For example, in 2019, scientists working in the Philippines announced the discovery of teeth and bones of a new species of hominid dating between 50,000 and 67,000 years old. It was called Homo luzonensis and overlapped in time with the hobbits and us, along with some of our other extinct relatives. And he had a different mix of ancient and modern traits than the hobbit, such as very small molars but larger premolars and curved finger bones.

This discovery, of another new hominid on a remote island in Southeast Asia, simply reinforces how much more we have to learn about our family tree. Excavations continue in the cave where the original hobbit was found. And anthropologists are trying all the latest genetic techniques to try to unravel the mystery of the hobbit at the molecular level. But so far, our attempts to extract DNA from hobbit bones have failed, because hot, humid caves are terrible for preserving DNA. But even newer methods, such as extracting ancient proteins, such as collagen, from bones, have not yet been tried. So perhaps there is still some hope of finding out where Homo floresiensis fits into our family tree.

And maybe that will help us better understand this particular chapter of human evolution, back when hobbits were real. Thanks to Raycon for supporting PBS Digital Studios. Raycon makes wireless earbuds that come with Bluetooth pairing, a portable charging pod, and 6 hours of playtime. Instead of traditional single-channel layout, Raycon uses True Wireless Audio, which uses independent frequencies for the left and right channels. Raycon's latest E25 model comes in six different color options and a noise-isolating fit with no cables or stems. The earbuds are also sweat-resistant if working out is your thing. For more information, visit buyraycon.com/eons.

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