11 January 2009
Necklaces reveal early man's intelligence
The date when our ancestors first began to use ornaments has once again been under debate. While good evidence exists for the use of natural objects modified as jewellery almost 100,000 years ago in southern Africa and the Middle East, the case for this having occurred twice as long ago in Europe has also been argued, and has now come under renewed scrutiny.
Perforated seashells from Blombos Cave and possible shell beads from Sibudu Cave, both in South Africa, date from 70,000-75,000 years ago, while perforated shells bearing traces of red ochre are known from the Grotte des Pigeons in Morocco at 82,500 years and from Qafzeh in Israel at 90,000 years ago. The latter were in layers that also had burials of anatomically modern humans of Homo sapiens type, while at Skhul, near Qafzeh, the Mousterian layers usually associated with Neanderthal man yielded two perforated shells. All of these are thought to have been used as pendants or necklaces, and wear on some of the perforations shows that those shells were strung.
"It has been repeatedly argued that personal ornaments are one of the innovations that emerged in Africa among early modern humans, and that they represent behaviours that allowed them to migrate out of Africa and determined their evolutionary success," said Solange Rigaud and her colleagues wrote in the Journal of Archaeological Science this month. One possibility, they suggest, is the use of naturally perforated small fossil sponges of the species Porosphaera globularis. Some were found in the Somme valley in northern France, from Acheulean period contexts dating from 200,000 years ago; others were found in Victorian times at Biddenham, Bedfordshire, and in an Acheulean site near Bedford itself.
Robert Bednarik has argued that the size, shape and perforation frequency of Porosphaera found in archaeological contexts differ from natural assemblages, and that micro-flaking around the holes was caused by hominid action to enlarge them.
Dr Rigaud's team compared some of these early archaeological specimens with later archaeological uses of the sponges in Bronze Age and Roman times, and also with a large sample of natural Porosphaera from the Baltic coast of Germany. The archaeological samples were larger, and had larger holes, than the control sample at a fairly high level of statistical significance.
There was insufficient stratigraphic dating evidence from the 19th-century excavations, however, to confirm that the sponges had been collected by hominids, rather than accumulated in the same deposits as man-made tools by chance, and more recent excavations failed to yield more examples. Nevertheless, some kind of sorting clearly occurred in the ancient collections to produce such different ranges of size and shape from the natural sample.
Dr Rigaud's team exclude natural sorting, leaving a choice between early hominids or 19th-century excavators, either of whom might have chosen only the most striking, or potentially useful, examples from a wider range. It is possible that the micro-chipping seen as ancient improvement of the perforations could have been made when the specimens were strung by the excavators or subsequent museum curators, although William Smith, excavator of the Bedford 'beads' was explicit about the abrasions being there when they were dug up.
A final verdict of "not proven" is the only one currently possible, the team conclude. "No other possible ornaments are found in this region" of Europe before about 40,000 years ago and the few possible uses of pigments "do not provide compelling support to the idea that symbolic cultures flourished in Europe during the Lower Palaeolithic" period. An open mind is the best strategy, given that only a few years ago the use of personal ornaments as long ago as 80,000 years would have been unthinkable.
Source: The Times (4 January 2009)