(CNN) – A hobbit-sized species of ancient human that lived on the Indonesian island of Flores until about 50,000 years ago has baffled scientists for several reasons.
Homo floresiensis, The scientific name of this extinct species, discovered for the first time almost 21 years ago, called into question the idea that human evolution developed in an orderly line from the most primitive to the most complex.
Experts don’t know why Homo floresiensis, Nicknamed the “hobbit” in a nod to JRR Tolkien’s fictional characters, he developed such a tiny body and lived relatively recently, how he crossed the depths of the ocean to reach the island of Flores, where exactly this tiny one is located. “oddball” in the human family tree or why it disappeared.
An analysis of the fossils of Homo floresiensis just described, published Tuesday in the academic journal Nature Communicationsattempts to answer some of these questions about the tiny human. The remains examined in the new study include a humerus fragment, the lower half of the upper arm bone, and two teeth discovered at a site known as Mata Menge, one of only two places on the island of Flores where They have found fossils of the species.
The study’s authors say their findings support an existing theory that “hobbits” evolved their small size a long time ago and were most likely a dwarf version of the Homo erectusthe first ancient human to leave Africa about 1.9 million years ago, with a body size and upright gait similar to those of modern humans. Remains have been found Homo erectus on the Indonesian island of Java and elsewhere in Asia and Africa.
The researchers believe that the Homo erectus It was isolated on the island about a million years ago and suffered a drastic reduction in its body size over a period of about 300,000 years. This type of size reduction occurs to other animals on remote islands in response to resource scarcity, the study notes.
“Perhaps, there was no need to be large-bodied, which requires more food and takes longer to grow and reproduce,” said study lead author Yousuke Kaifu, a professor at the University of Tokyo, via email. “On the isolated island of Flores there were no predatory mammals or other hominid species, so the small body size was fine.”
Based on the estimated length of the bone, the team calculated that its owner’s height was 100 centimeters (about 3.3 feet). The teeth found at the same site, although smaller in size, presented a “high degree of similarity” with the teeth of Homo erectus unearthed in Java.
Digital microscopy of the bone structure indicated that it belonged to an adult and not a child. The complete humerus would be between 21.1 and 22 centimeters in length, the smallest human limb bone fossil ever found.
The sediment layer containing the fossils was dated in previous research to be about 700,000 years old.
This early hobbit was 6 centimeters smaller than the original specimen Homo floresiensisa nearly complete skeleton found in Liang Bua Cave about 75 kilometers west of Mata Menge in 2003 and dated to about 60,000 years old. Liang Bua Cave is the only other place where hobbit fossils have been found.
The authors noted that the size disparity between the two could point to natural variation, such as that seen in modern human populations. Overall, the research suggests that the species’ small size remained remarkably constant over a long period.
The newly analyzed finds, along with other teeth, a jaw and a skull fragment, found at the same site and described above, represent four hobbit individuals. Combined with the more recent fossils from Liang Bua, they suggest that tiny humans were able to thrive on the island despite the presence of predators such as 3-meter-long Komodo dragons and crocodiles.
“The drastic early reduction and subsequent stability of body size indicated that having a smaller body size on this isolated island was beneficial for the survival of these archaic humans,” the study authors said in a statement.
The hobbit, along with the subsequent discovery of two other small-bodied and small-brained hominids who lived relatively recently, the Homo naledi in South Africa and Homo luzonensis in the Philippines, and the much larger Denisovans, has led to greater acceptance among paleoanthropologists that there have been many diverse species of humans, including several that coexisted with our own species, Homo sapiens.
Before the discovery of Homo floresiensismany experts in human evolution thought that only one human species had existed throughout time, with regional variations.
Not all scientists agreed with the study’s interpretation that the Homo erectus of large size was the ancestor of the Homo floresiensis and that the hobbit represents a dwarf version of the Homo erectussaid co-author Gerrit van den Bergh, a senior lecturer at the Center for Archaeological Sciences at the University of Wollongong in Australia.
According to other authors, the hobbit, with its small brain and wrists similar to those of chimpanzees, could be more related to small-bodied hominids, such as the Homo habiliswhich is only known in Africa.
Matt Tocheri, a Canadian professor of Human Origins at Lakehead University in Ontario, said he was not convinced the hobbit was a Homo erectus on a reduced scale.
“I agree that their evidence indicates that small-bodied hominids were present on Flores at least 700,000 years ago. But why does that have to mean that their immediate ancestors who first arrived on the island were larger?” said Tocheri, who is also a research associate in the Smithsonian Institution’s Human Origins Program.
“I think this question remains unanswered and will continue to be the subject of investigation for some time.”
Van den Bergh said the remains of the so-called Flores man unearthed in Mata Menge were found between 2014 and 2016. However, the humerus was broken into fragments and was not immediately recognized. One of the study’s authors later painstakingly pieced it together.
“The fossils are found in hard sandstone,” van den Bergh said by email. “We are forced to use metal chisels and hammers to break up the sediments, so some of the fossils are recovered in many pieces.”
To resolve the debate about the origins of the hobbit, hominid remains on Flores would be needed that date back further, to the time they arrived on the island, just over a million years ago, both van den Bergh and Tocheri stated.
When the hobbit was first discovered, some experts in human evolution claimed that the bones were those of a modern human with a growth disorder, such as microcephaly, a condition that causes an abnormally small head, a small body, and some cognitive impairment. . This claim sparked intense debate, but has since been widely rejected.
According to the study, no signs of disease were found in the humerus.
“Every little fragment of Homo floresiensis or any other hominid is incredibly important,” Tocheri said. “These fossils are our window to the shared evolutionary past of our species. Without them, we have no idea what happened in the past.”
