The secrets of floating gold

Ruairidh Macleod

Third year biological anthropology student Ruairidh Macleod has written a paper published by the Royal Society demonstrating for the first time that jetsam ambergris, also known as ‘floating gold’, is produced in all cases by sperm whales.

Ambergris, prized by the perfume industry for its musky scent, is a highly valuable but oddly mysterious substance. Secreted in the bile duct of the sperm whale, it can remain in the sea for decades, or even centuries, before being washed up and discovered. While it has long been known that much of it is the product of sperm whales, it has remained possible that it might have more diverse origins. Today’s paper appears to prove that sperm whales are the sole source.

“It has significant implications for understanding the origins of ambergris, and understanding the sperm whale’s metabolism and diet,” explains Ruairidh.

By sequencing the DNA of jetsam ambergris found in Sri Lanka and New Zealand, and comparing it with the DNA of a sperm whale found beached in the Netherlands, Ruairidh, in collaboration with a team of scientists in Copenhagen, has built up a more conclusive picture of the properties of ambergris than has ever been possible before.

“DNA methods are becoming more efficient, and ambergris preserves very well. It’s resistant to both microbial degradation and degradation from seawater, so some of the samples around today are up to 1000 years old. It’s possible that it also preserves gut microbiomes, which almost nothing preserves.”

As the genetic diversity of the whales around today has been reduced by population reduction, an expansion of the project to include more samples will also allow the team to assess the impact of whaling on the biology of surviving whales.

The breakthrough has generated international interest, including a write-up in the New York Times

"I remember Ruairidh mentioning this idea to me about a year ago - a concept unconnected with his coursework," says Homerton's Senior Tutor, Dr Penny Barton. "It is amazing to see it followed through and published in a distinguished journal in such a short time. It's a fantastic achievement by a truly creative undergraduate."