Use of hide glue in 4th millennium BC Europe

To test whether hide or fish glue was used to fix bark decorations to the body of a wood bow (of a different species) found during the archaeological excavation of at the site “Parkhaus-Opéra” in Zurich (Switzerland), dated by dendrochronology to 3175 - 3157 BC, we attempted extraction of collagen residues from wood flakes collected from two areas of the bow surface under the bark and their identification by on-line nanoflow reversed-phase C18 liquid chromatography tandem mass spectrometry.