Reporter covering the practice and culture of science.
April 10 at 1:00 p.m.
Please welcome a new member to our band of erect monkeys: Homo luzonensis, whose teeth and bones were discovered in an insular cave. The remains represent a new species, the scientists concluded in a report published Wednesday in the journal Nature. They called it that because of Luzon, the island in the Philippines where the remains were found.
Our genre, the homo in. Homo sapiens, contains crowds, including thick but sophisticated eyebrow neanderthals and Homo erectus, a species of almost 2 million years that can be our direct ancestor.
Homo luzonensis is the peculiar and extinct human fourth discovered in this century. Homo floresiensis, so small that it was nicknamed "the hobbit", was found in Indonesia in 2004. The mysterious Denisovans, identified as a species based on a finger bone in 2010, lived in Siberia. Homo Naledi sThe skeletons, with strange combinations of modern and primitive features, were removed from an African cave in 2013.
Together, these newly discovered species show that human evolution was highly versatile, as groups adapted to conditions unknown throughout the world. Modern humans were not alone, our close relatives survived until quite recently. And some of our cohabitants possibly embarked on long trips by sea, suggesting similar levels of intelligence.
"The evolution of our evolutionary group, Homo, is becoming increasingly rare," said paleoanthropologist Rick Potts, who directs the Smithsonian's Human Origins Program and did not participate in this research. Like Homo naledi, these fossils show a mix of old and new traits, Potts said. Their particular combination suggests that these humans were "previously unknown to science."
In 2007, Armand Mijares, an archaeologist at the University of the Philippines, asked his colleague Philip Piper to examine the bones of animals that Mijares had taken from the Callao cave in Luzon. The expansive cave yawns open on a river plain. A limestone chamber is so large that it houses a Catholic chapel. A deposit of bones in the entrance chamber dates back to the Pleistocene epoch, which lasted from 2.6 million to 11,700 years ago.
Piper, a zooarchaeologist at the National University of Australia, began cataloging the remains of animals. "The second day I was working with them," he said, "I took out a human metatarsal." Piper immediately called Mijares over the unexpected bone of the foot, exclaiming, as he remembered: "Oh, my God, we have Human bones in here!
The first chamber of the Cueva del Callao on the island of Luzon, in the Philippines, where the fossils of Homo luzonensis were discovered. (Cave Cave Archaeological Project)
Piper, Mijares and his team. published a description of the foot bone in 2010. They knew it was the oldest human remains in the Philippines, with an age of 67,000 years, based on the amount of uranium from the radioactive element in the fossil. But the 2010 newspaper did not address who walked on that foot. "We did not know what it was at that time, except it was human," Piper said.
Mijares returned to the cave of Callao and discovered more remains in 2011 and 2015. In total, the scientists removed from the cave a dozen fossilized parts: teeth, bones of thighs, bones of fingers and feet, representing three people. Attempts to extract DNA from the remains were unsuccessful.
The body parts are tiny, suggesting that Homo luzonensis did not grow more than 4 feet tall. Their molars have modern forms. The way the muscle in his leg attached to his thigh bone is "distinctly human," Potts said.
The bones of his hands and feet are curved, "spit images" of the toes and fingers that belonged to the very old. AustralopithecusSaid Piper. These hominids, like those of 3 million years. Australopithecus afarensis Lucy, she had very adequate digits to climb.
This species lived at the same time as humans with modern anatomy, who first appeared in the fossil record 200,000 years ago (or perhaps up to 350,000 years ago). "We continue to realize that a few thousand years ago, H. sapiens was definitely not alone on Earth," said study author Florent Detriot, a paleoanthropologist at the National Museum of Natural History in Paris.
New York University anthropologist Susan Anton, an expert on Homo erectus, was skeptical that the remains came from a new species. The authors of the study "have no head," said Anton, who described herself as "somewhat conservative and rather shameless." ("Thieves," unlike "partidores," are more reluctant to clbadify fossils or living organisms as different species.) Skulls, rich in anthropological details, would be more convincing, he said.
Every difference in the shape of bone or tooth is subtle. "That's one reason to be a little cautious about this," said John Hawks of the University of Wisconsin at Madison, who helped lead the expedition to excavate bones from Homo naledi and did not participate in this discovery. But those differences, taken together, constitute a "reasonable" case for a new species, he said.
The authors of the study do not know how Homo luzonensis arrived on the island, which at 42,000 square miles is the 15th largest island in the world.
Although these fossils are the oldest in the Philippines, the evidence for the room is even older; 700,000 years ago, the ancient butchers of Luzon sculpted a rhinoceros with stone tools. What species is unknown the killing?
"Some species of mammals found in Luzon seem to have come from the continent," Piper said. The Asian continent is 400 or more miles away through the Luzon Strait. But in the Middle Pleistocene, when glacial sheets enclosed vast amounts of water, sea levels dropped to 400 feet, Piper said.
Random climate events, such as tsunamis, may have swept people through a prehistoric sea while clinging to debris, Anton suggested. "After climatic events or accidents, you can get specially intelligent organisms to survive in places that maybe should not be," he said.
The hawks wondered if these humans deliberately crossed the ocean. "I would only say that when humans could see the land or they could smell it or they knew the signs, that the birds came from there, they looked for it," he said. "That is not a trait of Homo sapiens, it's something our ancestors and extinct relatives had."
It is also possible that the first inhabitants of Luzon meandered from the Indonesian archipelago, jumping through the chains of islands.
The cartoon version of evolution, in which a hunched ape becomes a tall, happy bipedal, suggests a journey with a destination. The reality is more disordered, particularly when the species adapt to the islands.
The confines of an island can quickly cause an evolutionary change; Charles Darwin saw this in the peaks of the finches. Small animals are enlarged, large animals shrink, light contrasts grow pronounced. "Think of the Galapagos Islands: Each of the islands has its own species of turtle," Piper said.
"Isolation plays games," said Potts. Homo floresiensis showed anthropologists that an island could be a "strange little laboratory of human evolution," he said. These bones reinforce that lesson.
"It's starting to look like the evolutionary process is really fluid," Potts said. "And it's surprising that it's so fluid where each species of Homo can actually be a story or a record." The result is a fusion of the modern and the old: molars that can be yours next to curved toes of millions of years.
Toe bone of a Homo luzonensis, showing the longitudinal curve. (Cave Cave Archaeological Project)
Is it possible that other human species have evolved in these island laboratories and that their fossils are waiting to be found? "I would not be surprised," Piper said.
Fifteen years ago, Hawks said, anthropologists attributed the worldwide success of Homo sapiens to our modern anatomy. These new discoveries, in remote corners, suggest that exceptionalism is not integrated into our brains or skeletons.
"The archaeological record now shows us that ancient human forms were much more adaptable, and I would say intelligent, than we imagined," Hawks said. "This is not Flores for Algernon," where, suddenly, we are super smart and everyone else in the world is behind us. Scientists are now investigating genomes for other clues about the survival of Homo sapiens, observing our metabolism or resistance to disease. "I would say that the doors have been opened, and we have not discovered where they are going."
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