In a handful of fossilized teeth and bones, scientists say they’ve found evidence of a previously unknown human species that lived in what is now the Philippines about 50,000 years ago. The discovery deepens the mystery of an era when the world was a melting pot of many different human kinds on the move.
Small-jawed with dainty teeth, able to walk upright but with feet still shaped to climb, these island creatures were a mix-and-match patchwork of primitive and advanced features in a unique variation of the human form, the scientists reported Wednesday in the journal Nature.
“Evolution creates mosaics of traits like this,” said anthropologist Matt Tocheri at Canada’s Lakehead University and the Smithsonian’s National Museum of Natural History Human Origins Program in Washington, D.C., who wasn’t involved in the project. The report makes “a good case that this is something new that we have not seen before,” he said.
The announcement of a new species brings a region of the Pacific once considered a backwater of evolution into the mainstream of early human development, several anthropologists who study human origins said.
Many specialists in human fossils believe that a half dozen or so species of hominins, as closely related human species are called, may have co-existed around the world between 50,000 and 250,000 years ago. Several intermingled with our direct ancestors, bearing children together and leaving a legacy of hereditary traits that affect our health and well-being today, recent studies of ancient DNA reveal.
- A Fossilized Finger Bone Offers New Clues to Human History (April 9, 2018)
- Scientists Find Oldest Known Specimens of the Human Species (June 7, 2017)
- Early Human Interbreeding More Widespread Than Thought, Study Suggests (Dec. 4, 2013)
- Video: Fossils Shed Light on Human’s ‘Hobbit’ Ancestors (June 8, 2016)
“For the first time, the Philippines is part of the evolutionary debate,” said archaeologist Armand Mijares at the University of the Philippines in Quezon City, who led the excavation team that discovered the fossils on the island of Luzon. “We can see now that the islands are a playground of human evolution and natural selection.”
The researchers formally named the newly discovered species Homo luzonensis in honor of the island where they found it. They unearthed the fossils from the floor of an immense limestone cavern called Callao Cave.
The scientists speculate that the creatures may have died elsewhere and then washed into a deep sinkhole that, over eons of erosion, developed into the modern cave system.
Working with wooden probes, the researchers pried loose several foot and hand bones, a partial thigh bone and teeth from a matrix of cemented sediments. It took three years of field work. The specimens belonged to two adults and a juvenile of the species.
“We recognized them almost immediately as hominin,” said paleoanthropologist Florent Detroit of the Museum of Man at France’s National Natural History Museum in Paris, who was the lead author of the research paper that formally proposed the new species.
“The molars were so tiny, so small. The pre-molars had two or three roots. I thought, Uh-oh,” he said. “This was clearly a human-like something.”
Using a technique called uranium-series testing, which measures the rate of radioactive decay in a sample, the scientists determined that the bones dated to a time between 50,000 and 67,000 years ago.
The creature’s teeth, toes and finger bones appear to mix aspects of the other human species in existence elsewhere at the time, including Homo sapiens, Denisovans, Neanderthals, Homo naledi and Homo floresiensis, nicknamed the hobbit species for its small stature and big feet.
So far, the scientists haven’t found evidence that these creatures used tools to hunt or to process their food, which might indicate how highly developed their brains might have been. The scientists also have been unable to isolate DNA from the bones and teeth that could be used to understand how closely they were related to other human species.
“The area is sub-tropical and wet and that makes the preservation of DNA really difficult,” said Dr. Mijares in the Philippines.
The scientists also don’t know how these creatures reached the island, which was isolated from the mainland of Asia in that primordial era by deep ocean, just as today. Their more primitive ancestors may have been washed ashore on storm-driven debris or perhaps sailed on rafts, as much as 700,000 years ago, they said.
“We don’t know how they got to Luzon,” said Dr. Detroit in Paris. “They crossed the ocean but we don’t know when and we don’t know how, but they did it a long time ago.”
In their new environs, the species most likely evolved out of contact with other hominin species, developing their unique variations on the human form in an evolutionary process that results from long-term isolation on a small island with limited food resources and a lack of predators, the scientists said.
No one knows why this species died out like so many other early hominin groups or why Homo sapiens is the only one that survives today.
“It is a wake-up call. This is just not what you’d expect in the islands of Southeast Asia at a time when our own species is making its incredible journey around the world,” Dr. Tocheri said.
Recent human evolution, he said “just got even messier, more complicated and a whole lot more interesting.”
Write to Robert Lee Hotz at firstname.lastname@example.org