What does the discovery of “Hobbit” fossils tell us about our tiny human relatives?
A small human relative called a hobbit, or Homo floresiensis, The new fossils suggest that it may have evolved from a larger ancestor that shrank upon arriving on the Indonesian island of Flores.
A fragment of a humerus was found at Mata Menge on the Indonesian island of Flores. Homo floresiensis It was discovered in the nearby Liang Bua cave.
The origin story of Homo floresiensis, A strange clan of humans who lived 60,000 years ago on the Indonesian island of Flores has been drawing attention. With their tiny bodies and brains, and relatively large feet, H. floresiensis Scientists have long wondered how hobbits evolved their unique body shape, but now the discovery of a tiny fossil arm bone from an early member of the species that lived about 700,000 years ago may help answer that question.
In 2004, researchers first H. floresiensis The nearly complete skull and partial skeletal remains of a woman who lived approximately 80,000 years ago were found buried in a cave called Liang Bua on the island of Flores.
The female skeleton, named LB1, is the “type specimen,” or representative of the species. From LB1, scientists have estimated that she was about 3 feet 6 inches (106 cm) tall, with a brain the size of a grapefruit and legs more than half the length of a femur. Along with other human bones found in the cave, dating to about 100,000 to 60,000 years ago, LB1 showed that the hobbit’s skull has characteristics similar to our own. Homo erectusBut the rest of the body Australopithecus afarensis (The most famous of these is a skeleton called Lucy).
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For many years, there has been debate over the origins of this group. Researchers have suggested that it may have been a descendant of already small and primitive early humans, e.g. Homo habilis or Australopithecus species, or have larger bodies and larger brains Homo erectus The third theory, which has been left out of the evolutionary debate, is that these people were modern humans with a medical condition that causes dwarfism.
In 2016, scientists revealed a fragment of a lower jaw and a tiny tooth that appears to belong to a more primitive dinosaur. H. floresiensis The remains of at least three individuals were discovered at the Mata Menge site, about 70 kilometers from Liang Bua on the island of Flores. The remains date back 700,000 years, long before modern humans appeared on Earth. (The oldest anatomically modern human fossils were found in what is now Morocco, about 315,000 years ago.) The similarities in the teeth and jaws led the researchers to argue that the area may have been ruled by a large hominin, possibly from a group that includes modern humans and their extinct relatives. Homo erectusThey migrated from Java, Indonesia, and settled on the island of Flores, where they dwarfed and eventually became tiny. H. floresiensis.
Researchers led by Professor Yosuke Kaifu of the University of Tokyo discovered a new arm bone at Mata Menge – an incomplete humerus just 8.8 centimetres long – as well as some additional teeth. The arm fossil is the first sub-skull bone found at the site.
The researchers had to estimate how long the bones were when the individual was alive, and used that length to estimate the hominin’s height at about 100 centimeters, or 6 centimeters shorter than the estimated height of the Liang Bua individual, says Gerrit van den Bergh, a researcher at the University of Wollongong in Australia.
The newly discovered teeth also contain clues. One of them is Homo erectus Found in Java, H. floresiensis Van den Bergh said the tooth was found in Liang Bua cave.
Importantly, all of the Mata Menge fossils are small. The teeth in the mandible and humerus are all smaller than those found at Liang Bua, Kaifu says. “This suggests that the fossils date back 700,000 years ago. Homo floresiensis It was at least as large as the one from 60,000 years ago, if not slightly smaller. Homo floresiensis “It’s from Liang Bua,” he added.
According to the survey results, Homo erectus Since they washed ashore on the island of Flores 1 million years ago, there has been no genetic exchange with humans on the mainland, and large Homo erectus evolved into something smaller Homo floresiensis “Through a process called island dwarfism,” van den Berg says, something similar appears to be happening to animals on Flores, such as: StegodonThe elephant’s ancient relatives are thought to have dwindled in size due to limited food sources, a lack of predators and a loss of need to forage long distances (which was helped by their larger size). H. floresiensisIts body size may have fluctuated over time due to changes in climate and environmental conditions. The species disappeared from the fossil record about 50,000 years ago, around the same time that modern humans arrived on the island.
“This confirms what many expected from the original announcement[in 2016]but it brings us new discoveries of fossils beyond the skull, not just teeth and jaws and heads,” says Karen Barb, a biological anthropologist at Midwestern University who led the Hobbit research. “This gives us a more direct idea of the body size of this older population from Flores.”
The humerus fragment is missing both ends, which are crucial in determining whether the specimen is from a juvenile or adult, but the researchers used other indicators that support the adult theory. Missing both ends also makes estimates of the total length uncertain, Barb said.
“The presence of post-cranial bones is important for inferring things like body size, because it’s not easy to infer body size from teeth in the skull,” says anthropologist Aida Gómez-Robles of University College London, who was not involved in the new study. “But at the same time, what[the researchers]found was a fragment of a humerus that had no end.”
The hope is that a more complete skull could date it closer to its hypothesized appearance. Homo erectus He will appear on the island and provide a more detailed account of how the Hobbits came to be.
