Take a creature that's just over three feet tall, with a brain the size of a grapefruit, oversized clown-shoe feet, and the ability to craft and hunt with stone tools. Is it another species? A sick or genetically defective human? Scientists have been arguing about this since the creature--dubbed Homo floresiensis, or "hobbit" to its friends--was first discovered in a cave on the Indonesian island of Flores back in 2003.
When NOVA's Alien from Earth premiered in 2008, the jury was still out. In one camp were scientists who believed the hobbit was a previously undiscovered species, a new branch on the tree of human evolution. In the other camp were critics who argued that the hobbit's diminutive skull was evidence of microcephaly, a disorder that causes the head and brain to develop abnormally. That would explain why the hobbits were still alive and kicking a mere 18,000 years ago, when modern humans were already living in Australia and more primitive hominids had long-since disappeared.
Since that premiere, though, a flurry of new evidence has accumulated suggesting that the hobbit really is a new species. With a rebroadcast of Alien from Earth coming up this week on some PBS stations (please check your local listings to find out when it will air near you, or watch it streaming online), we've compiled some of the latest discoveries about the hobbits and their history.
First, the hobbits' arrival on Flores has been pushed back by nearly 300,000 years. When Alien from Earth first aired, the oldest evidence of the hobbits was a cache of stone tools dated to about 700,000 years ago. But in 2010, scientists led by Australian archaeologist Adam Brumm announced that they'd discovered more stone artifacts, this time buried beneath an ash layer deposited by a volcano that erupted a million years ago; ergo, someone was making tools on Flores before the volcano went off.
Second, a close examination of hobbit foot bones revealed that the hobbits walked upright on disproportionately large feet. (Their feet measured seven and a half inches long.) Those big feet suggest that the hobbits' ancestry goes back to an even more primitive species than was first thought.
How could a healthy animal end up with such a scrawny brain? Creatures on isolated islands are known to balloon up and shrink down over many generations, two phenomena known as gigantism and dwarfism. In fact, Flores itself is home to funhouse-mirror creatures like giant storks, monster Komodo dragons, and pygmy elephants. Yet island dwarfs often end up with heads that are disproportionately large for their shrunken bodies, so many scientists doubted that this kind of island dwarfism could explain the hobbit's oddball proportions. But in 2009, scientists at London's Natural History Museum used skulls from two types of dwarf hippos (both now extinct) to create a new model for the scaling of brain size and body mass in dwarf species. Their model suggested that the hobbits could indeed be healthy island dwarfs.
But to know for sure whether the hobbit represents a new species, scientists would like to look at its DNA. It has been tried before, by teams from Germany and Australia, without success. Now, Christina Adler and her team at the Australian Centre for Ancient DNA are planning to give it another go, this time using a sample from a DNA-rich substance called cementum, which coats the roots of teeth.
Meanwhile, the Australian Research Council has funded more excavations on Flores. Archaeologists like Mike Morwood, one of the original discoverers of the hobbit bones, hope that these large-scale digs could turn up bones from hobbit ancestors one million years old--or even older.