Sir

Whiten and McGrew reported in Correspondence1 a fascinating Liberian postage stamp from 1906, suggesting that its image might be the first documentation of digging for termites by a chimpanzee. They identified the stamp as printed in London, but did not know the basis on which the image was composed.

Tool order: did the stamp-illustrator know more about chimpanzees than the original artist?

I have now solved the mystery. By chance I discovered the original drawing (see figure, right) that must have served as model for the Liberian stamp (figure, left), in a popular German book of the time2. The artist is Gustav Mützel (1839–1893), whose brilliant illustrations of mammals and birds are well known through works such as those of the zoologist Alfred Edmund Brehm and his father, the ornithologist Christian Ludwig Brehm. Mützel signed the chimpanzee picture, adding the note “n. d. Leben” to show that his drawing was from his own observation of a living ape's behaviour, not from a pelt, photograph or other illustration.

Whiten and McGrew are correct to praise the accuracy of the drawing, which is even visible on the stamp. But it is not of a wild ape. The figure shows the female chimpanzee Mafuka from Gabon, who lived in the early 1870s in Dresden zoo where Mützel drew her2. Mafuka and other zoo apes learnt to use tools without any instruction: for example, drinking carefully out of a glass or a cup by imitating their human companions. These observations were among the reasons for establishing an ape research station on Tenerife, where Wolfgang Köhler conducted his famous studies on the intelligence of anthropoids3. In Mützel's picture the ape is probably using a stick to explore a knot-hole in the trunk of a tree. But the natural-looking environment is added from the illustrator's imagination. There is no termite mound in the picture, so Jane Goodall remains the first person to document wild chimpanzees 'fishing' with tools for termites4.

This outcome of the mystery of the stamp seems at first sight to be somewhat disappointing. Nevertheless, the story tells us something, not about chimpanzees, but about the breadth of human culture and global information flow. A nineteenth-century German artist portrayed a young ape in Germany and added attributes of the ape's homeland to the scene. A British philatelic illustrator liked this African motif and transposed the scene from the German drawing to a Liberian stamp. Looking at the stamp nearly one hundred years later, two primatologists thought that it might be a record of tool use by chimpanzees in Liberia.