Discovery of Smallest Human Arm Bone Illuminates Evolution of Homo Floresiensis

Scientists unveiled the smallest adult limb bone ever discovered, shedding new light on the evolution of Homo floresiensis, the tiny “Hobbits” of Flores. This remarkable find, dated to 700,000 years old, reveals that these early hominins were even smaller than previously thought.

A groundbreaking discovery on the Indonesian island of Flores has unveiled the smallest adult limb bone ever found in the human fossil record, offering new insights into the evolution of Homo floresiensis, often dubbed the “Hobbits” of Flores. The findings, published today in Nature Communications, promise to reshape our understanding of these ancient, diminutive humans.

The bone, a tiny humerus fragment, dates back approximately 700,000 years and adds crucial evidence to ongoing debates about the origins and development of Homo floresiensis. First discovered in 2003 in Liang Bua cave by a team co-led by the late Mike Morwood, a New Zealand archaeologist, these small-brained hominins remained a mystery. Were they a dwarfed descendant of early Asian Homo erectus, or did they originate from a more ancient and already petite hominin species?

The new fossils, excavated from Mata Menge — an open-air site situated 75 kilometers east of Liang Bua — belong to at least four individuals and include teeth and the newly discovered arm bone. The bone’s diminutive size suggests these early hominins stood around 100 centimeters tall, roughly six centimeters shorter than Homo floresiensis from Liang Bua.

“This 700,000-year-old adult humerus is not just shorter than that of Homo floresiensis, it is the smallest upper arm bone known from the hominin fossil record worldwide,” Adam Brumm, a professor of archaeology at Griffith University and co-author of the study, said in a news release. “This very rare specimen confirms our hypothesis that the ancestors of Homo floresiensis were extremely small in body size.”

This discovery elucidates that extreme body size reduction began early in the evolution of Flores hominins. While their dental characteristics were less specialized than those found in Homo floresiensis, their small stature was already well-established.

“The evolutionary history of the Flores hominins is still largely unknown,” added Brumm. “However, the new fossils strongly suggest that the ‘Hobbit’ story did indeed begin when a group of the early Asian hominins known as Homo erectus somehow became isolated on this remote Indonesian island, perhaps 1 million years ago, and underwent a dramatic body size reduction over time.”

These findings represent not only a scientific triumph but also a testament to the persistent efforts to unravel the origins of these fascinating ancient humans. As research continues, each discovery like this humerus fragment brings us closer to fully understanding the remarkable evolutionary journey of Homo floresiensis.