Very Distant Relative

Artist’s rendering of Homo floresiensis with its skull shown

© Katrina Kenny 2017

Homo floresiensis is a small hominid—roughly three-and-a-half feet tall and estimated to weigh around 70 pounds—discovered over a decade ago in Liang Bua Cave on the island of Flores, Indonesia. The remains found to date include a nearly complete female skeleton that scientists have nicknamed “the Hobbit.” The species is thought to have used stone tools, hunted small elephants, and survived amongst predacious komodo dragons.

The relationship between H. floresiensis and other hominids has been the subject of debate since the fossils’ discovery. One theory suggests it evolved from a population of Homo erectus—a larger species whose remains have been found nearby on Java, Indonesia—and dwarfed in response to the constrained resources on Flores. Another theory suggests it is a direct descendent of an early hominid from Africa. Yet another hypothesis proposes that the bones of the female skeleton, at least, represent a Homo sapiens with a genetic condition (such as Down syndrome) that led to its size and character differences. 

To understand the ancestry of H. floresiensis, paleoanthropologist Debbie Argue of the Australian National University and her team conducted a detailed comparison of H. floresiensis with 11 other hominid species using 133 cranial, postcranial, mandibular, and dental measurements. Once a database of characters was created, it was analyzed with software designed to quantify phylogenetic relatedness between species.

The researchers found that H. floresiensis did not share a close relationship with H. erectus, as would be expected if H. floresiensis had descended from this species. Instead, they found a closer relationship with H. habilis, supporting the idea that H. floresiensis is a longsurviving population of an early hominid lineage from Africa, perhaps via a previously unknown migration. Their results also indicate that H. floresiensis is not a modern human (H. sapiens).

“This [finding] challenges so many of our ideas about human evolution,” says Argue, adding that although the remains of H. floresiensis date to the relatively recent past (roughly 60,000 years ago), their closest relatives appear to have lived two million years ago in Africa. There is still much to understand about this small hominid, such as how it came from Africa to be living on a small island in Indonesia—a question that Argue will be investigating next. (Journal of Human Evolution)