One species of ancient human the size of a “hobbit” who lived on the Indonesian island of Flores until about 50,000 years ago intrigues scientists in several ways.
First unearthed in a surprising discovery nearly 21 years ago, Homo floresiensis, the scientific name for the extinct species, challenged the idea that human evolution unfolded in a linear fashion, from primitive to complex.
Experts don’t know why Homo floresiensis — nicknamed the “hobbit” after JRR Tolkien’s fictional characters — evolved to have such a small body despite having lived relatively recently, as it crossed the deep ocean to reach the island of Flores, where to place this diminutive peculiar in the human family tree, or why it disappeared.
An analysis of newly described Homo floresiensis fossils, published Tuesday in the journal Nature Communications, tries to answer some of these questions about the little human. The remains examined in the new study include a fragment of a humerus — 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 fossils of the species have been found.
The study authors said their findings support an existing theory that “hobbits” evolved their small size long ago and were most likely a dwarf version of Homo erectus, the first ancient human to leave Africa about 1 year ago. .9 million years old, with a body size and upright posture similar to modern humans. Remains of Homo erectus have been found on the Indonesian island of Java and other parts of Asia, as well as in Africa.
The research team believes the first human isolated himself on the island about a million years ago and underwent a dramatic reduction in body size over a period of about 300,000 years. This size reduction happens to other animals on remote islands in response to limited resources, the study noted.
“Perhaps there was no need to have a large body, which requires more food and takes longer to grow and reproduce,” study lead author Yousuke Kaifu, a professor at the University of Tokyo, said in an email. “The isolated island of Flores was devoid of mammalian predators and other hominid species, so the small size was acceptable.”
Based on the estimated length of the bone, the team calculated the owner’s height to be 100 centimeters tall. The teeth found at the same site, although smaller in size, bore a “high similarity” to those of Homo erectus unearthed in Java.
Digital microscopy of the bone’s structure indicated that it belonged to an adult, not a child. The complete humerus would be between 21.1 centimeters and 22 centimeters long, the smallest fossil human limb ever found.
The layer of sediment that contained the fossils has been dated in previous research to about 700,000 years ago.
New revelations about Homo floresiensis
This early “hobbit” was six centimeters shorter than the original specimen of Homo floresiensis, a nearly complete skeleton found in Liang Bua Cave — about 75 kilometers west of Mata Menge in 2003 — and dated to about 60,000 years ago. Liang Bua Cave is the only other place where “hobbit” fossils have been found.
The size disparity between the two specimens could indicate natural variation, as seen in modern human populations, the authors noted. Overall, the research suggested that the species’ small size remained remarkably constant over a long period.
The recently analyzed finds, along with other teeth, a jaw fragment and skull fragment unearthed in the same location and described previously, represent four “hobbit” individuals. Together with the most recent fossils from Liang Bua, they suggest that small humans were able to thrive on the island despite the presence of predators such as 3-meter Komodo dragons and crocodiles.
“The initial dramatic reduction and subsequent stability of body size indicated that having a smaller body size on this isolated island was beneficial to 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, small-brained hominins that lived relatively recently—Homo naledi in South Africa and Homo luzonensis in the Philippines—and the much larger Denisovans, led to wider 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 floresiensis, many human evolution experts thought that essentially only one species of human had evolved over time, with regional variation.
The origin of “hobbits”
Not all scientists agreed with the study’s interpretation that large-bodied Homo erectus was the ancestor of Homo floresiensis and that the “hobbit” represents a dwarf version of Homo erectus, said Gerrit van den Bergh, co-author and senior lecturer at the Center. of Archaeological Science at the University of Wollongong in Australia.
With its small chimpanzee-like braincase and wrist bones, the “hobbit” may be more closely related to small hominids such as Homo habilis, known only from Africa, others have argued.
Matt Tocheri, chair of human origins research at Lakehead University in Ontario, Canada, said he was not convinced that the “hobbit” was a scaled-down version of Homo erectus.
“I agree that your evidence indicates that small hominids were present on Flores at least 700,000 years ago. But why must this mean that your 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 a focus of research for some time.”
Van den Bergh said the “hobbit” remains 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 reconstructed it.
“The fossils occur in hard sandstone,” van den Bergh said in an email. “We are forced to use metal chisels and hammers to break up the sediments, and therefore some of the fossils are recovered in many pieces.”
To resolve the debate over the origins of the “hobbit,” you would need hominin remains on Flores that date back to the period when they arrived on the island just over 1 million years ago, both van den Bergh and Tocheri said.
When the “hobbit” was first discovered, some human evolution experts argued that the bones belonged to a modern human with a growth disorder — such as microcephaly, a condition that leads to an abnormally small head, a small body, and some cognitive impairment. This claim sparked fierce debate, but has since been widely rejected.
No signs of disease were found in the humerus, according to the study.
“Every little fragment of Homo floresiensis or any other hominid is incredibly important,” Tocheri said. “These fossils are our window into the shared evolutionary past of our species. Without them, we have no idea what was happening in the past.”
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