The sign of the ancient mariner

Henry Gee

Fossil humans belonging to the species Homo erectus could have made boats and gone island-hopping across deep-water straits in what is now Indonesia almost a million years ago, according to a report in the 12 March 1998 Nature. Such navigational ability has always been assumed to have been the prerogative of our own species, Homo sapiens.

M. J. Morwood of the University of New England, New South Wales and colleagues discuss stone tools and bones of fossil elephants and other animals, buried between 800,000 and 900,000 years ago on Flores, in the Lesser Sunda island chain east of Java. When sea-level was at its lowest, during the last Ice Age, much of what is now Indonesia was joined up into a single landmass, which included Borneo, Java and Sumatra. Even then, Flores was separated by three deep-water channels, the narrowest 19 km wide. To reach Flores, animals would have to have flown there, been washed ashore on rafts, swum across, or been carried on boats.

Suggestions that stone tools on Flores and elsewhere in offshore Indonesia could represent a very early phase of human navigational ability have usually met with disbelief. The problem has been establishing that the stone tools really were deposited at the same time as the animal bones, and were not made more recently and mixed in by processes of erosion and re-disposition. But Morwood and colleagues have laid that criticism to rest, with firm dates showing that the tools at a site called Mata Menge, on Flores, really are around 800,000 years old. But a site called Tangi Talo, around 100,000 years older, has a different set of animals and no stone tools, suggesting (but not proving) that humans were not in the area at that time.

This age suggests that the makers of the tools were Homo erectus, because, as far as we know, there were no members of Homo sapiens in Asia at the time. Not only that, these creatures would have to have crossed the open sea not once, but three times.

Current fossil evidence suggests that Homo erectus appeared in Africa around 2 Ma. They travelled far and fast: 1.8-m.-y.-old specimens have been recovered from Java. (Getting to Java would have been no problem, as it was joined to Asia for significant periods during the Ice Age). H. sapiens, although a close relative of H. erectus, did not appear until much later, also in Africa. H. sapiens may have reached Flores by 900,000 years ago, though it is unlikely: H. erectus seems to have been the toolmaker: and, perhaps, the boatmaker.

The finding has several implications. Although Homo erectus is thought to have been able to have made fire, its cultural abilities have traditionally been thought rather inferior to that of Homo sapiens. For example, H. erectus made hand-axes in more or less the same way for a million years, and examples have been found throughout the Old World.

However, could the making of stone tools be just a part of a more extensive and more imaginative toolmaking tradition, one that encompassed perishable, organic materials such as wood and other plant materials, such as we see in so-called 'primitive' cultures to this day? This is supported by the discovery in Germany (reported in Nature last year) of 400,000-year-old wooden spears, perfectly shaped for throwing: spears from people (arguably the European descendants of H. erectus) that lived long before modern humans or even Neanderthals came to northern Europe.

Macmillan Magazines Ltd 1998 - NATURE NEWS SERVICE

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