Sunday, February 1, 2009

Earlier start for human art?

Back in 2002, a team working at Blombos Cave in South Africa reported finding two 77,000 year old pieces of ochre (one of which is pictured here) etched with what appears to be a deliberate cross-hatched pattern. The findings were published in Science, and I wrote about them at the time. A couple of years later, the same team, led by Christopher Henshilwood of the University of Witwatersrand in South Africa and the University of Bergen in Norway, reported equally old shell beads that may have been used as personal ornaments. Many, although not all, researchers interpreted these finds as evidence of early symbolic behavior and maybe even art. Indeed, the discoveries eventually convinced many scientists that symbolic behavior did not begin during the so-called "Upper Paleolithic creative explosion" in Europe 40,000 years ago but much earlier.

In this week's Science, I report on new finds of etched ochre, some dated 100,000 years old, from Blombos Cave. The work was presented at a meeting in Cape Town in January and is also in press at the Journal of Human Evolution. Here are a few extracts of my report:

To analyze the latest finds, Henshilwood teamed up with Francesco d'Errico of the University of Bordeaux in France and independent ochre expert Ian Watts, who is based in Athens. The trick with ancient ochre is to figure out what early humans were using it for. Many previous studies have concluded that ochre was often ground to make a powder, which could have been used to paint bodies--a form of social identification usually considered symbolic--or for more utilitarian purposes. For example, Lynnette Wadley of Witwatersrand has argued from modern-day experiments that ground ochre could have been used as a kind of glue to haft stone tools into wooden or bone handles.

So Henshilwood and colleagues focused their attention on 13 pieces engraved in ways that seemed inconsistent with grinding alone. Some pieces have lines arranged in apparent fan-shaped or crosshatched designs; others are etched in wavy patterns. Microscopic examination showed that these engravings had been made with a pointed stone tool and a finely controlled hand.

Of the 13 pieces, eight were found at levels reliably dated to about 100,000 years ago. And Henshilwood's team argues that the findings of similar etched pieces at both 77,000 and 100,000 years ago is particularly significant:

... some of the oldest pieces have a crosshatched pattern similar to that of the two original ochre pieces dated to 77,000 years ago. And other researchers have very recently discovered similar crosshatched patterns on a few African stone and bone objects thought to be as old as the new finds, or nearly so. This refutes suggestions that the marks are merely doodles, Henshilwood says, and suggests a 25,000-year tradition of symbolic representation.

I quote a couple of researchers who aren't entirely convinced, on various grounds, that the pieces indicate symbolic behavior. But even if they did, we will probably never know what they really meant to the people who engraved them.


Woody said...

Did they use carbon-dating to establish the age of artifacts of 50,000 years or greater, which knowledgeable scientists know can be done?

Michael Balter said...

Thanks for your question, Woody, but radiocarbon dating cannot be used for materials older than 50,000 years and certainly not at the Blombos levels of 75,000 years and older. For this, dating methods such as optically stimulated luminescence and thermoluminescence are required.

Woody said...

Well, it's nice to know that radiocarbon dating is now accepted as going beyond the "absolute maximum" of 45,000 years.

Sometimes I wonder why mankind made so little progress over 100,000 years, just exiting the stone age not that long ago. Now, we make more progress in a month than they did over the entire span of humans before that. Why is that?