How 16th century shipwrecked ivory can assist with today’s anti-poaching strategies
In 1533 a Portuguese trading ship sank off the coast of what is now present-day Namibia. Its 40 tons of cargo included gold and silver coins along with around 100 elephant tusks. These preserved tusks varied in size, ranging from 2-33 kg in weight and came from male and female elephants. Despite being underwater for nearly 500 years, the tusks were in good condition due to the cold waters of the Namibian coast
An international team of scientists has now examined the tusks using paleogenomic and stable isotope analysis. They identified the nuclear DNA as coming from African forest (Loxodonta cyclotis), rather than savanna (Loxodonta africana) elephants. These elephants historically ranged across the entire Guinean and Congolian tropical forest blocks of West and Central Africa.
Using Mitochondrial sequences, which is passed down from females, the team traced the tusks to West Africa, from at least 17 different elephant ‘herds’. Comparing these with the most up to date genetic information about modern elephants, they found that only 4 of the same lineages still exist today in modern West Africa. This means that all the other lineages have become extinct, probably due to indiscriminate hunting elephants for their ivory over the last five centuries.
“That was quite shocking – that loss of diversity,” said Dr Coutu. “Next we’d really like to fill in those gaps in a chronological way. We can look at where these pinch points are in history and create a timeline of exactly how and when the huge trade in ivory had an impact.”
“[What we found] definitely has conservation implications,” Dr de Flamingh added: “We know that a loss of genetic diversity is associated with increased extinction risk.”
By studying the chemical elements in the tusks (stable isotopes of carbon and nitrogen) they found that these elephants had lived in scrubby woodland savannahs, not the deep tropical forests along the West African coast where almost all forest elephants live today.
“This information gave us a picture of the ecology of the West African forest elephant in its historic landscape. Knowing more about historic environments in which forest elephants thrived will benefit wildlife conservation today,” said Dr Ashley Coutu.
The scientists hope that their detailed examination of the shipwrecked ivory could help inform anti-poaching efforts today. Whilst recent figures suggest elephant poaching has slightly decreased, they are still being poached across the region. Confiscated tusks can be analysed to find out where the elephants originated, so the historic evidence found in the Born Jesus shipwreck can be used to provide a comparable reference, so its origin can be confirmed.
“And once you know where the ivory is from you can develop targeted anti-poaching strategies for those locations,” says Dr de Flamingh. Dr Coutu added that “we’re really going to be able to use this historic data to answer modern conservation questions.”
The 16th century shipwreck was identified as the Bom Jesus, a Portuguese trading vessel which was lost in 1533 whilst sailing to India. Elephant tusks were a valuable commodity in the 1500s and were often traded from Africa to Europe, the Middle East, and Asia. The find, of such a large number of well-preserved tusks, was unique.
This study was the first to combine genetic, archaeological and historical methods and was led by Oxford University’s Pitt Rivers Museum and School of Archaeology alongside partner institutions in Namibia (the National Museum of Namibia), South Africa (University of Cape Town, University of Pretoria) and the USA (University of Illinois).
You can read the full research paper – Sourcing Elephant Ivory from a Sixteenth-Century Portuguese Shipwreck – in Current Biology.
Main photographs – Top: gold 10-cruzado coins (cross insignia), minted under the reign of King João III of Portugal in 1525 and withdrawn in the 1530s, helped to date and identify the ship. Bottom: the shipwreck cargo included more than 100 unworked elephant tusks. Images: Amy Toensing; National Geographic Image Collection.