Birch tar is an adhesive dating back to the European Middle Palaeolithic. Several possible production pathways have been derived from experimentation and their complexity is often used to argue for complex behaviours or cognitive capacities of Neanderthals and early Homo sapiens. Efficiency may help to evaluate the likelihood that one technique or another was used in the Palaeolithic. Based on published and new experimental data, we analyse the efficiency of four birch tar production methods in terms of resource and time consumption. We found that there are differences in efficiency between all these methods, but they are not as great as previously thought. The most complex underground technique is most efficient in terms of tar yield but even the least complex aboveground condensation method produces usable amounts of tar in relatively short time intervals. Our findings highlight that efficiency cannot be used to evaluate the likelihood that specific techniques were used in the Palaeolithic. Only direct archaeological data on the techniques used in the Palaeolithic will allow to make inferences about the behavioural complexity of birch tar production.

桦木焦油是一种可以追溯到欧洲旧石器时代中期的粘合剂。从实验中得出了几种可能的生产途径，它们的复杂性经常被用来论证尼安德特人和早期智人的复杂行为或认知能力。效率可能有助于评估旧石器时代使用一种或另一种技术的可能性。基于已发表的和新的实验数据，我们分析了四种桦木焦油生产方法在资源和时间消耗方面的效率。我们发现所有这些方法在效率上都存在差异，但并没有之前想象的那么大。最复杂的地下技术在焦油产量方面最有效，但即使是最不复杂的地上冷凝方法也能在相对较短的时间间隔内产生可用量的焦油。我们的研究结果强调，效率不能用于评估旧石器时代使用特定技术的可能性。只有关于旧石器时代使用的技术的直接考古数据才能推断出桦木焦油生产的行为复杂性。