Kristi Lewton and her colleagues wanted to reconstruct a walk that ended at least 60,000 years ago. They studied LB 1, a likely female member of the extinct human species Homo floresiensis, commonly known as the “hobbit people.” She stood about 3 feet 6 inches tall and left behind two incomplete hip bones in Liang Bua cave on the Indonesian island of Flores.
Early accounts described the upper parts of those bones as flaring away from the body. That made LB 1 look more like much earlier human relatives. But the result depended partly on how researchers measured the pelvis, and different techniques could produce conflicting interpretations.
A study published in the American Journal of Biological Anthropology has now found that LB 1’s pelvis was more like those of other members of Homo than early descriptions indicated. All but one measurement fell within the range recorded in modern humans. The researchers say the anatomy points to a human-like form of upright walking in Homo floresiensis.
How the Homo floresiensis Pelvis Was Measured
Iliac flare is the term for how far the upper sections of the hip bones spread away from the body. The shape changes the position of muscles that keep the hips stable when a walker raises one foot from the ground.
Explore All OptionsLewton’s team made a 3D model from micro-CT scans of LB 1’s pelvis and recorded seven measurements. Their comparison included 21 modern humans, 20 chimpanzees, 20 gorillas, and 26 fossil individuals.
The researchers measured flare by placing one digital plane across the upper hip blade and another along the edge of the hip socket. This allowed them to compare every specimen using the same type of measurement. LB 1 fell within the range seen among members of Homo.
When the researchers looked at several pelvic features at once, LB 1 fell near some Pleistocene Homo specimens and some australopiths. Even so, her pelvis had more in common with small-bodied members of Homo than earlier accounts had recognized.
The angle may not capture everything anatomists mean by iliac flare. The analysis is also based on one incomplete Homo floresiensis pelvis, while some comparisons relied on casts, reconstructions, or previously published measurements.
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A Longer Ischium
The exception was the ischium, the section extending below and behind the hip socket. LB 1’s ischium was long for her body size, exceeding the range in the modern human sample and nearly every other fossil examined.
In living primates, a longer ischium is often associated with less hip extension while walking on two legs. It can also give the hamstrings greater leverage during climbing. This means LB 1 may have held her hips in a more flexed position or moved efficiently in trees. But the length may just reflect how much pelvic anatomy can vary within Homo and may have had little effect by itself.
Her thighbones were relatively short; her small hip joints would have made running hard on her body, and her feet had long, curved toes and little or no arch. She walked on two legs, but her body was probably not built for fast running or long journeys.
What the Pelvis Says About the Hobbit People
The pelvis may also help researchers understand where Homo floresiensis fits in the human family tree. The species may have descended from Homo erectus or another early Homo population. A different small-bodied ancestor is still possible. The researchers also found that LB 1’s pelvic proportions cannot be explained by her small size alone.
The team plans to reconstruct the complete pelvis, which could show more clearly how the bones worked together. The surviving pieces already show that LB 1 moved upright through Flores, although the exact details of her stride remain uncertain.
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Article Sources
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- This article references information from a study published in the American Journal of Biological Anthropology: Comparative Morphometric Analysis of the Pelvis of LB 1 (Homo floresiensis)
