De Young’s research could improve authentication by identifying the species of trees used

The longtime African art collector Richard Scheller, a leading biochemist and an executive vice-president at the biotech corporation Genentech, is working with Lesley Bone, the chief curator at the De Young Museum in San Francisco. “There is a constant issue around authenticity in African art,” Scheller says, and the pair decided that identifying the species of trees used could help to address this issue. “If the species of tree didn’t grow on the continent of Africa, then you might wonder if your object was authentic or not.” Works have also been X-rayed and CT scanned in the run-up to “Embodiments: Masterworks of African Figurative Sculpture” (until 5 July), an exhibition at the museum of 120 pieces from Scheller’s collection. He donated works to the institution in 2013 and 2014, and has pledged to give more in the future.

Working first with modern objects, Scheller and his team at Genentech, which funded the research, discovered that they could chemically extract and sequence DNA from dead wood. By comparing it with a public database of chloroplast (organelles found in plant cells) DNA, they were able to identify the species of tree. They then turned to the works in Scheller’s collection, removing just enough sawdust from the bottom of three sculptures to repeat the process used with the newer wood. The results were extraordinary: the team was able to extract DNA that was 100 to 200 years old, proving that it could still be found in materials that had been dead for many years. Bone believes this is the first time that this process has been applied to a work of art made from wood.

Finding a species DNA match in the database presented a challenge, however. “When we made the DNA from the art objects, we found that we were only able to establish distant relatives,” Scheller says. “There are 300,000 species of plants on earth and only around 400 have been deposited in the database so far.” The team was unable to find exact species matches for any of the works, but a Jonga sculpture from the Democratic Republic of Congo returned the highest number of database matches; these pointed to the Madagascar rosy periwinkle, which is found in Central Africa. The nearest relatives identified in the other two works, although more distant, were also from families of trees commonly found in Africa.

Endless possibilities

For Scheller, the process was a success. “That it’s possible to do this is the question that we were asking,” he says. “It is possible to take wood, make DNA and determine the species.” Although the database needs to expand before this process can be fully utilised, Bone and Scheller are confident that this information will be available in the near future, given the advances made in DNA sequencing during the past decade. Once the database catches up, the possibilities for research are endless.

“In ten years, this could become a very powerful tool,” says Bone, who believes that it holds the promise of great discoveries for curators, from establishing material trade routes to understanding how materials shifted with tribal migration. Scheller agrees, citing reports of tribes that created certain sacred objects using particular species of trees. Comparing the DNA of these objects would make it possible to determine if they came from the same species, so confirming their shared provenance.

Does this signal a change in the way African art is authenticated? “In the future, yes,” Scheller says. “For now, no. It’s too new and it’s too sophisticated scientifically. I think it will take a while.”

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