Callao Cave on Luzon Island, Philippines. Image : Callao Cave Archaeology Project Scientists are reporting the discovery of a previously unknown species of ancient human that lived in the Philippines over 50,000 years ago. Evidence suggests the new species, named Homo luzonensis, was exceptionally tiny—and possibly even smaller than the famous Hobbit species uncovered on the island of Flores in 2004. Advertisement The story of human evolution just got a hell of a lot messier—and considerably more fascinating—owing to the discovery of a previously unknown human species. Bits of teeth and bone pulled from Callao Cave on the Philippine island of Luzon point to the existence of a distinctly human species, one deserving of the Homo designation in terms of its genus. At the same time, however, the fossils found in Callao Cave exhibit features unlike anything ever seen before, thus warranting the declaration of a completely new human species, Homo luzonensis. The details of this astonishing discovery were published today in Nature. Needless to say, this is a huge deal. New human species tend to not be discovered on a regular basis. The discovery of Homo luzonensis, with its curious set of physical characteristics, is telling us some surprising new things about human evolution and what happened to the pioneering hominins who left Africa so long ago. This story begins in 2010 with the important discovery of a single human foot bone, dated at 67,000 years old, in Callao Cave. The exact species could not be determined, but it was the first direct evidence of a human presence in the Philippines. As an important aside, we’ve since learned that hominins—the sub-group of primates that are more closely related to us than to chimpanzees and bonobos—were living in the Philippines as long as 709,000 years ago. A butchered animal bone found a the Kalinga site in Luzon, Philippines, showed hominins were active on the island as far back as 709,000 years ago. The newly discovered species, called Homo luzonensis, lived in the Philippines around 67,000 years ago. It’s not known if the two groups were related. Image : Thomas Ingicco, Mission Marche aux Philippines Indeed, the story of human evolution is getting increasingly complicated. Hominins first appeared in Africa some 6 to 7 million years ago, with the first evidence of a hominid presence in Eurasia dating back about 1.8 million years ago, likely the archaic human known as Homo erectus. Incredibly, this dispersal happened long before our species, Homo sapiens, emerged; we finally entered onto the scene 300,000 years ago, spilling into Eurasia about 100,000 years later. There, we joined two other human species, the Neanderthals and Denisovans. Most extinct hominins are not our direct ancestors, but they’re our very close relatives. Each species went on its own evolutionary journey, adapting to their new circumstances and environments in different ways. By around 50,000 to 60,000 years ago, there were multiple human species living at the same time, doing their own thing at various locations in both Africa and Eurasia. Advertisement The scientists who found the human foot bone in the Philippines, a team led by Florent Détroit from the National Museum of Natural History in France and Armand Mijares from the University of the Philippines, kept working at Callao Cave in an effort to find more clues. These ongoing excavations resulted in the discovery of 12 new hominin elements, including teeth, a partial thigh bone, and several hand and foot bones. These fossils belonged to three different individuals, two adults and one child. No genetic evidence could be extracted from the specimens, and sadly, no skulls were found. These remains were pulled from the same stratigraphic layer as the foot bone found in 2010, dating these individuals to the same time period. Analysis of the bones and teeth suggested a previously unknown species of human. Also, these hominins appear to have been exceptionally small. The authors of the new study suspect H. luzonensis was subject to an evolutionary process known as insular dwarfism, in which a species’ body size becomes significantly reduced over time on account of limited access to resources. A similar thing likely happened to Homo floresiensis, an extinct human species popularly known as the Hobbit. The remains of these diminutive humans, who stood no taller than around 3 feet and 7 inches (109 centimeters), were discovered on the island of Flores in Southeast Asia back in 2004. The discovery of Homo luzonensis—who may have been shorter than the Hobbits—may signify the presence of yet another human species moulded by insular dwarfism—a rather astounding discovery, to say the least. It’s important to point out, however, that insular dwarfism in H. luzonensis remains a distinct, yet unproven, possibility. As the authors noted in the study, “further discoveries and more definitive evidence are needed.” Advertisement The Hobbits and H. luzonensis bear striking similarities, and they were around at roughly the same time, but their evolutionary relationship is not known. It’s conceivable that both human species are descendents of H. erectus, and that both ended up isolated on their respective islands. Five upper teeth of the newly described human species, Homo luzonensis. Image : Callao Cave Archaeology Project Advertisement In terms of the distinct physical differences observed in H. luzonensis, the most notable were seen in their teeth and foot bones. Their molars, in particular, were unlike anything ever seen before in a human species. Writing in an accompanying News & Views article, anthropologist Matthew Tocheri from Lakehead University in Thunderbay, Ontario, described how their teeth exhibited both ancient and modern features. When compared with the molars of other hominin species, H. luzonensis molars are astonishingly small, and the simplified surfaces of their crowns and their low number of cusps are features that look similar to the molar crowns and cusps of H. sapiens. Yet the shapes of H. luzonensis teeth share similarities with the teeth of H. erectus from Asia, and the size ratio of H. luzonensis premolars to molars is similar to that of Paranthropus, species of which are known for their massive jaws and teeth. Advertisement This is unbelievably fascinating, but the story gets even more intriguing—and potentially even more confusing. The third metatarsal—the long bone in the middle toe—in H. luzonensis is exceptionally strange, bearing an uncanny resemblance to those seen in Australopithecus—an ancient human ancestor that lived in Africa some 3 million years ago and never left Africa. Well, at least to the best of our knowledge. H. luzonensis also featured hand bones similar to those of Australopithecus. Advertisement The toe bone in question: The third metatarsal of H. luzonensis. Image : Callao Cave Archaeology Project There are at least two possible explanations for this odd toe bone, neither of which seem wholly plausible. Advertisement Crazy theory number one: Conventional thinking has it that Homo erectus was the only hominin species to have left Africa during the Early Pleistocene, the period between 2.58 to 0.78 million years ago. The evidence found in Callao Cave would seem to suggest that we’ve got it all wrong, and that other hominins, including groups more closely related to Australopithecus (or even Australopithecus itself! ), made their way into Eurasia during this period. More evidence is needed to back this extraordinary possibility. Crazy theory number two: An intriguing aspect about the H. Luzonensis third metatarsal is that it allows for more curved toes. This is significant because curved toes are great for tree climbing and hanging from branches. Australopithecus, a suspected tree climber, was equipped with this particular physical feature, and it would seem to suggest the same for H. luzonensis. But if H. Luzonensis is not closely related to Australopithecus, then why the curved toes and hands? It’s possible that some hominins retained their tree-climbing abilities for much longer than is conventionally appreciated. Another possibility is convergent evolution, in which similar physical characteristics appear in unrelated species. Should this be the case, if would mean that, after thousands of years of upright, bipedal locomotion, H. Luzonensis was returning to an arboreal existence, and evolving the requisite physical characteristics. It’s a mind-blowing theory, no doubt, but again, one in desperate need of further evidence. Advertisement<doc-sep>A new species of ancient human, thought to have been under 4ft tall and adapted to climbing trees, has been discovered in the Philippines, providing a twist in the story of human evolution. The specimen, named Homo luzonensis, was excavated from Callao cave on Luzon island in the northern Philippines and has been dated to 50,000-67,000 years ago – when modern humans and the Neanderthals were spreading across Europe and into Asia. Florent Détroit, of the Natural History Museum in Paris and the paper’s first author, said the discovery provided the latest challenge to the fairly straightforward prevalent narrative of human evolution. It was once thought that no humans left Africa until about 1.5 million years ago, when a large-bodied ancient human called Homo erectus set off on a dispersal that ultimately allowed it to occupy territory spanning Africa and Spain, China and Indonesia. Then, according to the traditional narrative, after a few hundred-thousand years of not much happening, our own ancestors dispersed from Africa about 50,000 years ago. “We now know that it was a much more complex evolutionary history, with several distinct species contemporaneous with Homo sapiens, interbreeding events, extinctions,” said Détroit. “Homo luzonensis is one of those species and we will [increasingly see] that a few thousand years back in time, Homo sapiens was definitely not alone on Earth.” Some of the teeth that were found belonging to Homo luzonensis. Photograph: Callao Cave Archaeology Project The excavation did not yield a complete skeleton: seven teeth, two hand bones, three foot bones and one thigh bone were found, thought to belong to two adults and one child. Nevertheless, the fossils provide intriguing clues to the appearance and lifestyle of Homo luzonensis. The tiny teeth suggest the human would have been shorter than 4ft tall – possibly even shorter than another ancient species, Homo floresiensis, sometimes called the “hobbit”, also found in south-east Asia and dating to about the same period. Most intriguing was the presence of a curved toe bone, which closely resembled the anatomy of far more ancient species such as Australopithecus, known only in Africa and dating to 2m-3m years ago. Normally this anatomy would indicate a mixed lifestyle with an ability to walk on two legs and climb trees. One possibility is that this primitive trait reappeared once the species had become isolated on the island. “Maybe the way they were walking was distinct,” said Détroit. “This is something we plan to work on in the near future.” It is not known whether the new species, along with the ‘hobbit’, represent earlier dispersals from Africa than Homo erectus, or whether they are descendants who later shrank and evolved new anatomical traits. The Homo floresiensis ‘hobbit’ skull compared with a modern human skull. Photograph: Yousuke Kaifu Another mystery is how they arrived at Luzon, a large island that has never been connected to the mainland by a land bridge. One possibility is that the early humans set out to sea intentionally on some form of raft; another is that they were washed there in relatively large numbers due to a natural event such as a tsunami. “Arrival by accident … is favoured by many scholars, but this is mainly because of arguments like ‘Homo erectus were not clever enough to cross the sea on purpose’,” said Détroit. “But the fact is that we have now more and more evidence that they successfully settled on several islands in the remote past in south-east Asia, so it was probably not so accidental.” Chris Stringer, head of human origins research at the Natural History Museum in London, who was not involved in the find, said another crucial question is what caused the demise of these early humans and whether our own ancestors played a role. “As for the fate of luzonensis, it is too early to say whether the spread of Homo sapiens into the region at least 50,000 years ago might have been a factor in its disappearance,” he said. The findings were published in the journal Nature.<doc-sep>In an article published in Nature, Matthew Tocheri from Lakehead University in Canada, who was not involved with the research, commented: "Explaining the many similarities that H. floresiensis and H. luzonensis share with early Homo species and australopiths as independently acquired reversals to a more ancestral-like hominin anatomy, owing to evolution in isolated island settings, seems like a stretch of coincidence too far."<doc-sep>
Fossil bones and teeth found in the Philippines have revealed a long-lost cousin of modern people, which evidently lived around the time our own species was spreading from Africa to occupy the rest of the world. It’s yet another reminder that, although Homo sapiens are now the only surviving members of our branch of the evolutionary tree, we’ve had company for most of our existence. And it makes our understanding of human evolution in Asia “messier, more complicated and whole lot more interesting,” says one expert, Matthew Tocheri of Lakehead University in Thunder Bay, Ontario. In a study released Wednesday by the journal Nature, scientists describe the cache of seven teeth and six bones from the feet, hands and thigh of at least three members of the species. They were recovered from Callao Cave on the island of Luzon in the northern Philippines in 2007, 2011 and 2015. Tests on two samples show minimum ages of 50,000 years and 67,000 years. Right upper teeth of an individual of the newly identified species Homo luzonensis, found in Callao Cave in the Philippines. Callao Cave Archaeology Project / Reuters The main exodus of our own species from Africa that all of today’s non-African people are descended from took place around 60,000 years ago. An analysis of the bones from Luzon led the study authors to conclude they belonged to a previously unknown member of our “Homo” branch of the family tree. One of the toe bones and the overall pattern of tooth shapes and sizes differ from what’s been seen before in the Homo family, the researchers said. They dubbed the creature Homo luzonensis. It apparently used stone tools and its small teeth suggest it might have been rather small-bodied, said one of the study authors, Florent Detroit of the National Museum of Natural History in Paris. H. luzonensis lived in eastern Asia at around the same time as not only our species but also other members of the Homo branch, including Neanderthals, their little-understood Siberian cousins the Denisovans, and the diminutive “hobbits” of the island of Flores in Indonesia. There’s no sign that H. luzonensis encountered any other member of the Homo group, Detroit said in an email. Our species isn’t known to have reached the Philippines until thousands of years after the age of the bones, he said. But some human relative was on Luzon more than 700,000 years ago, as indicated by the presence of stone tools and a butchered rhinoceros dating to that time, he said. It might have been the newfound species or an ancestor of it, he said in an email. Detroit said it’s not clear how H. luzonensis is related to other Homo species. He speculated that it might have descended from an earlier human relative, Homo erectus, that somehow crossed the sea to Luzon. H. erectus is generally considered the first Homo species to have expanded beyond Africa, and it plays a prominent role in the conventional wisdom about evolution outside that continent. Some scientists have suggested that the hobbits on the Indonesian island descended from H. erectus. The first chamber of Callao Cave where fossils of newly identified hominin species Homo luzonensis were discovered on Luzon Island, in the Philippines, on April 10, 2019. Callao Cave Archaeology Project / Reuters Tocheri, who did not participate in the new report, agreed that both H. luzonensis and the hobbits may have descended from H. erectus. But he said the Philippines discovery gives new credence to an alternate view: Maybe some unknown creature other than H. erectus also slipped out of Africa and into Europe and Asia, and later gave rise to both island species. After all, he said in an interview, remains of the hobbits and H. luzonensis show a mix of primitive and more modern traits that differ from what’s seen in H. erectus. They look more like what one what might find in Africa 1.5 million to 2.5 million years ago, and which might have been carried out of that continent by the mystery species, he said. The discovery of the new human relative on Luzon might be “smoke from a much, much bigger fire,” he said. Michael Petraglia of the Max Planck Institute for the Science of Human History in Jena, Germany, said the Luzon find “shows we still know very little about human evolution, particularly in Asia.” More such discoveries will probably emerge with further work in the region, which is understudied, he said in an email.