A piece of early human evolutionary history has been unlocked in the Philippines, where researchers unearthed fossils of two adults and one child more than 50,000 years old at Callao Cave.

Southeast Asia isn't widely known as a hotspot for archaeology, but this groundbreaking discovery could get scientists flocking to the region soon.

In a new study published in the journal Nature, researchers introduce the ancient human species Homo luzonensis, named after the island of Luzon.

What The Bones Tell Scientists

During the dig at Callao Cave, archaeologists were able to unearth an adult finger, toe bones, and teeth, as well as a child's femur.

One of the features that struck the scientists as interesting is the extremely small teeth of the individuals.

Since the size of the teeth are often reflective of the overall body size of a mammal, the team believe that the new human species was likely relatively diminutive, according to Philip Piper, a coauthor from the Australian National University.

Until they find skeletal elements, the researchers are unable to determine exactly how small they are.

What the researchers did note is how similar the hand and feet bones are to the primitive Australopithecines, an ape-like ancestor of the Homo group who are known to last walk the Earth in Africa roughly 2 million years ago.

In a report on NPR, paleoanthropologist Shara Bailey from the New York University calls the new humans a "mosaic species," with an unusual mix of ancient and modern traits.

For instance, one of the toe bones is extremely similar to the toe of the Australopithecines. The teeth are even more of a blend with a number of them very similar to modern humans and the others more like human ancestors from millions of years ago.

"So, the question is whether some of these features evolved as adaptations to island life, or whether they are anatomical traits passed down to Homo luzonensis from their ancestors over the preceding 2 million years," Piper explains.

Recent excavations at Callao Cave also revealed evidence of a butchered rhinoceros and stone tools from about 700,000 years ago. It's still unclear whether these belong to the Homo luzonensis or another hominin species.

New Humans May Rewrite Ancient History

Aside from the new Homo luzonensis, the Homo floresiensis or "the hobbit" has also been discovered in Indonesia, another Southeast Asian country. The two hominin species actually share a number of traits, particularly the strange mix of ancient and modern characteristics.

With two unique species found in the region, scientists are trying to figure out the path of ancient humans took in their migration out of Africa, according to NPR.

Many hold the belief that the first group of human ancestors to travel out of Africa was the Homo erectus about 2 million years ago.

One explanation for the presence of the pair of oddball species in the region is that a group of Homo erectus arrived in the Philippines where some of their characteristics evolved to become similar to modern humans and others did not.

Another possibility is that a different ape-like species, not the Homo erectus, made their way to the remote islands of Asia.

These new possibilities are exciting, but they also indicate an evolutionary history that's messier than previously believed.

Rick Potts of the Smithsonian Institution's National Museum of Natural History explains to NPR that it will challenge the belief that there was a neat and orderly progression of human evolution from primitive to modern.

Whatever it means in the puzzle of human evolution, the discovery puts Philippines on the map as a significant region in the evolution of early humans.

"I'm very proud, because as a Filipino and Southeast Asian, we tend to be on the periphery of this debate," Armand Mijares, study author and project leader from the University of the Philippines, tells National Geographic. "Now, we can be actively engaged in the debate, because our areas—our sites—are now recognized."

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