A horncore feature was encountered during excavations at Border Cave, in Member 2 BSL, dated 60–49 ka. The basal half of the horncore lay towards the centre of a combustion feature and was calcined. The tip half lay on a mat of burnt grass bedding towards the edge of the fireplace. It was covered with a black shiny residue, which was also present on nearby stone tools. The feature was jacketed and excavated later under a microscope in the laboratory. Raman spectroscopy identified the residue only as amorphous carbon, indicating the presence of a heated organic substance. Knowing that variation exists in modern and archaeological glue recipes, we wanted to know if the black residue was melted keratin, and if it was, whether it had been used as a substitute for beeswax or latex for hafting. We set out to test the hypothesis by conducting a heating experiment with a modern sheathed horncore. Experimental results showed that keratin does not transform into viable glue when heated. Instead, it reduces immediately to a glassy brittle residue. Our finding strongly supports a scenario of incidental deposition of residue on the archaeological stone tools. Previous combustion experiments have shown that the sediment below a fire can reach 300+ °C through vertical heat transfer. This implies that horn sheaths in archaeological deposits, separated from overlying combustion features by thousands of years, can transform into a black residue that may deposit on nearby stone and bone tools.

中文翻译：

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热量对角蛋白的影响及其对考古记录的影响

在BSL成员2 BSL（日期为60-49 ka）的Border Cave进行挖掘时遇到了角核特征。角铁的基部一半朝向燃烧特征的中心并被煅烧。笔尖的一半朝着壁炉的边缘躺在一块烧焦的草床上。它上面覆盖有黑色光泽残留物，该残留物也存在于附近的石材工具上。对该特征进行了护套处理，随后在实验室的显微镜下进行了挖掘。拉曼光谱法仅将残留物鉴定为无定形碳，表明存在加热的有机物质。知道现代和考古胶水配方中存在变化之后，我们想知道黑色残留物是否是熔化的角蛋白，如果是，则是否已将其用作蜂蜡的替代品或用于柄的乳胶。我们着手通过使用现代护套角铁进行加热实验来检验该假设。实验结果表明，角蛋白在加热时不会转变成活的胶。相反，它立即减少为玻璃状脆性残留物。我们的发现有力地支持了残留物在考古石器上偶然沉积的情况。先前的燃烧实验表明，火下的沉积物可通过垂直传热达到300+°C。这意味着考古沉积中的角鞘与上覆的燃烧特征相隔了数千年之久，可以转化为黑色残留物，可能沉积在附近的石头和骨骼工具上。它立即减少为玻璃状脆性残留物。我们的发现有力地支持了残留物在考古石器上偶然沉积的情况。先前的燃烧实验表明，火下的沉积物可通过垂直传热达到300+°C。这意味着考古沉积中的角鞘与上覆的燃烧特征相隔了数千年之久，可以转化为黑色残留物，可能沉积在附近的石头和骨骼工具上。它立即减少为玻璃状脆性残留物。我们的发现有力地支持了残留物在考古石工具上偶然沉积的情况。先前的燃烧实验表明，火下的沉积物可通过垂直传热达到300+°C。这意味着考古沉积物中的角鞘与上覆的燃烧特征相隔了数千年之久，可以转化为黑色残留物，可能沉积在附近的石头和骨骼工具上。