Java man : how two geologists' dramatic discoveries changed our understanding of the evolutionary path to modern humans

In October 1887, Dutch physician Eugene Dubois set sail for the Dutch East Indies (now Indonesia), in pursuit of the 'missing link' that would prove man was a descendant of the apes. Unable to gain funding for his project, Dubois joined his country's army, making time for fossil hunting in between his regular duties. His discovery of a fossilised skullcap and femur led him to the conclusion of the existence of what he called Anthropithecus erectus, more commonly known as 'Java Man'.
Dubois' find, together with subsequent discoveries, such as the 'Mojokerto child' in 1936, revolutionised conventional thinking about mankind's origin. Now recent scientific developments in the field of geochronology have turned anthropology on its head once more. Using advanced dating techniques, Carl Swisher and Garniss Curtis returned to the fossil finds of Indonesia and made an amazing discovery: the fossils were far older than had previously been thought, firm evidence that homo erectus had been in Indonesia two million years ago. The find solved the question of why it supposedly took homo erectus so long to migrate from Africa - the truth was the movement had actually occurred far earlier.
But the geochronologists did not stop there. As well as finding evidence for the existence of homo erectus in Indonesia earlier than before, they also found evidence that the species existed far more recently, as little as 30,000 years ago. And this discovery points the way to a fundamental rethink of human evolution. Rather than a steady 'sapienization' from two million years ago to the recent past, the evidence suggests that several species co-existed on Earth, including Neanderthal Man, and for whatever reason - economic competition, violent confrontation - it was homo sapiens that drive the others to extinction.

Carl Swisher is a palaeontologist, geochronologist and a member of the Berkeley Geochronology Group at the University of California, Berkeley.