Two-tusked narwhal from Hamburg is a male

The specimen with the catalogue number ZMH-S-10192, brought to Hamburg in 1684 by a Dutch whaling expedition, was considered a sensation for centuries. It was believed to be the only known female with two tusks. Now, the new study clearly shows:

‘The Hamburg specimen is – like all other two-tusked narwhals known to date – a male,’ explains Prof. Thomas Kaiser, head of the Mammalogy & Palaeoanthropology Section at LIB, who was involved in the study.

Science as a process of learning

For the international research team led by researchers from Greenland and Denmark, the Hamburg skull was a key object in a more comprehensive study that actually investigated whether unusual dental features – such as two or specially shaped tusks – influence the diet of narwhals. The researchers wanted to find out whether such dental anomalies could cause the animals to hunt different prey or consume their food in different ways.

Using DNA-based sex determination and isotope analyses of bone collagen, the researchers were able to reconstruct both the sex and long-term aspects of the animal's feeding ecology. Their findings showed that the two-tusked animals did not differ in their diet from ordinary narwhals. At the same time, the genetic data clearly proved that the Hamburg specimen was also a male, contrary to what had long been assumed.

A historical leaflet from 1684 had previously suggested that the animal preserved in Hamburg was a unique specimen – a two-tusked female narwhal. For centuries, this document shaped the image of the museum's so-called ‘Mona Lisa’.

‘The scientific methods that have only recently become available now prove beyond doubt that our Hamburg “Mona Lisa” – contrary to what a historical document had always suggested – is in fact a male,’ says Prof. Matthias Glaubrecht, project manager of the New Natural History Museum (Evolutioneum) at the LIB. ‘I am delighted that, in collaboration with the team in Copenhagen, we have succeeded in verifying the historical documents with new findings. However, the mystery of how the story of a female narwhal came about remains.’

‘The new findings are also beneficial from the perspective of science communication,’ adds Prof. Simone Rödder, head of the Centre for Knowledge Transfer at the LIB. ‘They make it clear that science is a constant process of questioning and learning. Last but not least, the new findings demonstrate the value of collecting and archiving, which is what the Museum of Nature Hamburg stands for.’

A rare treasure – and living scientific history

Only around twenty two-tusked narwhals are known to exist worldwide. The Hamburg specimen thus remains one of the rarest exhibits of its kind – and at the same time impressive evidence of how modern research can correct historical errors.

The story of the whale illustrates how knowledge evolves – and how important museums are in enabling such insights to be gained even centuries later.

Publication:
Louis M, Rey-Iglesia A, Routledge J, de Jager D, Skovrind M, Heide-Jørgensen MP, Kaiser TM, Kovacs KM, Lydersen C, Rosing-Asvid A, Szpak P, Lorenzen ED:

Impact of Tusk Anomalies on the Long-Term Foraging Ecology of Narwhals.  Ecology and Evolution. Ecology and Evolution, 2025; 15:e72376

http://dx.doi.org/10.1002/ece3.72376