Under the sea
Tusks from ocean bed off Namibia reveal where elephants were killed for ivory five centuries ago
New research paper analyses largest ever archaeological cargo of African ivory
For nearly five centuries, 100 elephant tusks lay undisturbed on the seabed, holding secrets about the trade relations Africa had forged with European and Asian merchants, and the areas in which elephants were being killed for the ivory industry.
Now, a group of scientists at the University of Illinois at Urbana-Champaign have been able to analyse them to find out exactly where the elephants had roamed before they were killed for their tusks.
On March 7 1533, the tusks had been loaded onto a Portuguese trading vessel, along with gold, silver, copper and other cargo that weighed about 40 tons, but the vessel named Bom Jesus never reached its destination, and for centuries it was recorded as missing as no wreckage was ever found.
Then, through sheer luck in 2008, a geologist working for the De Beers mining company off the coast of present-day Namibia came across a copper ingot that was preserved well enough to still carry a trident-shaped mark on it.
That insignia turned out to be the hallmark of one of Renaissance Europe’s wealthiest merchants — a man named Anton Fugger who, like many other European merchants, had traded ingots for spices in the Indies during the 16th century.
The shipwreck is named as the oldest and most valuable ever discovered on the coast of Sub-Saharan Africa because the sheer weight of the cargo meant it was compressed down into the ocean bed, creating a perfectly preserved treasure trove for latter day archaeologists.
The latest breakthrough comes from scientists who conducted a genomic analysis of DNA extracted from the well-preserved tusks “to determine the species of elephants, their geographic origins and the types of landscapes they lived in before they were killed for their tusks”.
The ivory had been stowed in a lower level of the Bom Jesus under a weighty cargo of copper and lead ingots, said Alida de Flamingh, a postdoctoral researcher at the University of Illinois at Urbana-Champaign who led the study.
“When the ship sank, the ingots compressed the tusks into the seabed, preventing a lot of physical erosion by sea currents that can lead to the destruction and scattering of shipwreck artefacts,” she added, “and there is also an extremely cold sea current in that region of coastal Namibia, which likely also helped preserve the DNA in the shipwrecked tusks.”
The team extracted DNA from 44 tusks which revealed that they came from African forest elephants and not savannah elephants.
A further examination of mitochondrial DNA, which is passed only from mothers to their offspring, offered a more precise geographic origin of the elephant tusks than is otherwise available.
De Flamingh said, “Elephants live in matriarchal family groups, and they tend to stay in the same geographic area throughout their lives. By comparing the shipwrecked ivory mitochondrial DNA with that from elephants with known origins across Africa, we were able to pinpoint specific regions and species of elephants whose tusks were found in the shipwreck.”
All 44 tusks were from elephants from West Africa.
None originated in Central Africa.
“This is consistent with the establishment of Portuguese trading centres along the West African coast during this period of history,” de Flamingh said.
The team used DNA to trace the elephants to 17 family lineages, only four of which are known to persist in Africa.
The team is adding the new DNA sequences to the Loxodonta Localiser, an open-access tool developed at the University of Illinois which allows users to compare mitochondrial DNA sequences collected from poached elephant tusks with those in an online database collected from elephants across the African continent.