Introducing Homo floresiensis
The chance discovery of ancient bones on an Indonesian island in 2003 had momentous implications, challenging the long-standing orthodoxy on human evolution.
The partial remains of a woman of early human form were unearthed in a limestone cave on Flores by an Australian-Indonesian team of archaeologists led by Michael Morwood. Barely one metre tall, she had long, flat feet and a grapefruit-sized brain. Also excavated were the bones of at least eleven similarly sized individuals.
The find, reported in the magazine Nature in 2004, created global headlines and shook the science world.
Hailed as one of the most extraordinary discoveries by paleoanthropologists (who study fossilised hominids) in half a century, it also triggered intense controversy over just how Homo floresiensis, as these miniature beings were soon named, fitted into the human family tree.
Spats about species
Morwood and his colleagues were convinced that the “hobbits” constituted a hitherto unknown species. Pointing to their unique anatomical characteristics, they concluded that these tiny Indonesians were probably descended from the Homo erectus species which once inhabited Java.
Others argued that the hobbits’ ancestors were more likely to have been the older, smaller-brained Homo habilis species. And yet others attributed their tiny stature to a genetic disorder, such as Down syndrome or microcephaly.
There is now general consensus that, regardless of their origins, Homo floresiensis’s forerunners underwent “dwarfing” – a shrinking process seen in mammals confined to an island – and evolved into an endemic species.
Morwood’s team came across the remains while searching for early evidence of Homo sapiens’s migration to Australia from mainland south-east Asia via the Indonesian archipelago.
They measured the female skeleton’s cranial capacity by filling the skull with mustard seeds – a standard method. It was, it turned out, two-thirds smaller than those of modern humans.
Subsequent work, deploying new techniques to date the rock layers in which the bones were deposited, indicated that hobbits roamed Flores’s tropical landscape about 100,000 to 60,000 years ago.
Stone tools found at the cave suggested they were present even earlier: from at least 190,000 years ago.
Meanwhile, a dig at another Flores site uncovered teeth and a jawbone fragment belonging to at least three individuals, including two children, all of whom resembled Homo floresiensis. They were dated to at least 700,000 years ago.
By examining excavated tools, researchers deduced that the hobbits’ ancestors arrived on Flores about a million years ago. They lived alongside Stegodons (pygmy elephants), Komodo dragons and giant rats.
It was clear from the discovery of the hobbits that humans had been travelling by sea much earlier than was previously believed.
It had also been thought that Homo sapiens evolved for three million years via a single line of descent in Africa, before migrating to other parts of the world.
The emergence of Homo floresiensis pointed to several different lines of evolution and, possibly, an earlier migration from Africa to eastern Asia two million years ago.
Intriguingly, it seems that the hobbits – along with some local fauna – were wiped out on Flores at around the time modern humans spread through the region. Did Homo sapiens play a part in their demise?