Figure 1. Thin cross-sections of two medieval femoral bones. (a) The specimen shows large areas that have been destroyed by so-called bore-channels as a result of microorganisms colonizing the bone. If the biogenic decay is highly advanced, then the chance of extracting DNA indigenous to the specimen is very low. (b) An almost intact specimen. Given an effective purification of the ancient DNA extract that removes possible enzyme inhibitors, specimens such as this are usually highly suitable for successful PCR analysis.

Figure 2. Electropherograms of multiplex autosomal STR amplifications (‘genetic fingerprinting’) of three medieval bone specimens (WG 342 in lane 12, WG 631 in lane 17 and WG 134 in lane 15). The amplification products generated by dye-labelled primers occur in different colours (B=blue, G=green and Y=yellow). Typically, genetic fingerprinting of degraded DNA shows significantly lower peak heights (vertical scale in dimensionless fluorescence units) for fragments exceeding 200 bp (horizontal scale). This indicates that comparatively few long intact templates were present in the ancient DNA extract, although many templates contained fragment lengths smaller than 200 bp.