Sir

We recently took part in the Royal Society's New Frontiers in Science 2000 Exhibition, presenting an exhibit based upon our report in Nature of extensive cultural variation in tool use and other behaviour in wild chimpanzees1. The primary aim of this annual exhibition is to communicate the work of scientists to the public, but we found information flowed in both directions.

Of particular note, following the appearance of the exhibition at the Royal Society of Edinburgh, was that Peter Sharp drew our attention to a Liberian postage stamp that was issued in 1906 (see above).

Although primatology appears to have been unaware of it, the image may be the earliest accurate depiction of tool use in chimpanzees (perhaps in any animal), antedating by at least half a century the photographic records that later illustrated the first systematic scientific accounts of such behaviour, published in Nature by Jane Goodall2.

By contrast with earlier depictions, the image is remarkably correct in overall anatomy and posture, including knuckle-walking with the left hand and plantigrade positioning of the feet. Approaching a termite mound ( Macrotermitinae, probably Macrotermes), the chimpanzee wields a stout stick of the dimensions later documented as associated with digging into such mounds to access the termites3,4. We know of no scientific report of termite-digging for Liberia.

The basis on which the image was composed remains unknown.

Michael Harvey of the philatelists Stanley Gibbons Limited has identified the stamp as one of a set printed in London by Perkins Bacon, a now defunct company. The stamp appeared as an illustration in Liberia (1906), by the naturalist and philatelic illustrator, Sir Harry Johnson, but no clues to the origin of the image appear there, nor in two earlier volumes he drew on heavily5,6. Thus, the trail has gone cold.

Any assistance from your readers in tracing the origins of this scientifically intriguing image will be gratefully received.