Even as hominid settlers in Europe seemed to neaten up the story of human evolution, a restless hominid in Asia threatened to turn the whole thing messy again.
In November an international team of researchers confirmed that a 1.9-million-year-old human ancestor had been found in China, making it the oldest Asian known and supporting theories that hominids made their way out of Africa not around 1 million years ago as previously thought but more than 2 million years ago. The find also cast doubt on just who those early wanderers were.
These momentous fossils aren’t much to look at: a few teeth and a fragment of jawbone. Chinese researchers discovered them several years ago, along with some very simple stone tools, in a 1.9-million-year-old layer of sediment at Longgupo (Dragon Hill) Cave in south central China. They originally thought the teeth belonged to Homo erectus, supposedly the first hominid to arrive in Asia. But after detailed examination, paleoanthropologist Russell Ciochon of the University of Iowa concluded the teeth--shown here in a computer reconstruction that highlights their essential features--were more primitive than those of erectus. They most resembled teeth from Homo habilis, a small hominid that lived in East Africa more than 2 million years ago. The tools, too, were similar to those first used by habilis, with their natural shape requiring little modification.
This seems to be the tool kit that this first globe-trotting hominid used, says Ciochon. And this is really the first link between what’s going on in East Africa and Asia. Shortly after the evolution of Homo in Africa 2.5 million years ago, and shortly after the origin of the most basic stone-tool technology, we have hominids leaving Africa and populating the rest of the Old World. In Asia, he says, this hominid gave rise to erectus.
Ciochon isn’t saying the later migration from Africa to Asia never happened. Indeed, he thinks that there may have been three great movements out of Africa, with each wave of travelers giving rise to a multitude of hominid species around the world, all of which were ultimately replaced by whoever gave rise to us. Human evolution is bushy, says Ciochon, with branches that go nowhere. You don’t just have Australopithecus leading to Homo habilis leading to Homo erectus leading to Homo sapiens. This lineal idea is just kind of bogus. It was all very simple in the past, but it’s all wrong.