Branches appearing on human family tree
Fossils of tiny people further theory that two or more humanoid species lived at the same time.
When researches unveiled evidence of an extinct race of dwarf humans on a remote island in the Indonesian archipelago last week, the news bordered on fantasy - even to anthropologists.
It wasn't just the fact that this island seemed to be Middle Earth in miniature, with its hobbit-size humans. It was also the fact that no more than 18,000 years ago - a holiday weekend, by anthropological reckoning - we were not the only humans on the planet.
For decades, many anthropologists have posited that humans must have evolved like all other animals - in evolutionary trials and failures. Just because there is only one species of human today - homo sapiens - doesn't mean that there weren't several living together in the past, they say.
Now, researchers are increasingly finding fossils that support that idea. Moreover, this finding and a handful of others suggest that diversity existed across the entire arc of human history - from millions of years ago until almost the present day.
"The increased rate of discovery of fossils has shown diversity," says William Kimbel of the Institute of Human Origins at Arizona State University in Tempe.
Three years ago, Maeve Leakey found a hominid fossil from the same epoch as the legendary "Lucy," pointing to a diversity of hominids 3.5 million years ago. Two years ago, the unexpected features of another find in Chad at least hinted at a diversity of hominids as many as 7 million years ago, though it remains the subject of debate.
The fossils are physical markers of an idea established in the 1970s and increasingly accepted. Before then, most anthropologists believed that the human family tree was a single trunk from the primitive to the present, and every species of hominid could fit consecutively into this one human lineage. In the 1970s, however, researchers found almost certain evidence of two concurrent hominid species. All of a sudden, the tree had at least one branch. Since that day, perhaps the greatest debate in the study of human origins has been this: How many branches are there and when did they split?
Last week's extraordinary announcement has become another battle point.