The first use of birch tar adhesives by Neandertals over 191,000 years ago marked a significant technological development. The ability to produce entirely new materials through transformative... Show moreThe first use of birch tar adhesives by Neandertals over 191,000 years ago marked a significant technological development. The ability to produce entirely new materials through transformative processes was unlike anything that had been done before. In southern Africa, during the Middle Stone Age, humans made compound adhesives by combining disparate ingredients, a task which is believed to have required modern-like levels of cognition. However, for all of the significance given to ancient adhesives in discussions about Neandertal and modern human technological and cognitive capabilities, our knowledge of the material itself is limited. This thesis provides the first comprehensive study of Middle Palaeolithic and Middle Stone Age adhesives, providing new insight into the material choices and technological capabilities of Neandertals and Middle Stone Age humans. Finally, as awareness for the importance of Palaeolithic adhesive residues continues to increase, and more discoveries are made, new questions and materials that need to be tested are constantly being brought to light. Show less
Plant exudates appeared long time ago in the history line of life in the early Devonian. They are typical saps produced by specialized cells. They can be naturally excreted outside or right after... Show morePlant exudates appeared long time ago in the history line of life in the early Devonian. They are typical saps produced by specialized cells. They can be naturally excreted outside or right after plants are damaged or infected. Through time, diverse cultures recognized them as valuable sources of natural medicines. Of various types of plant exudates, the most outstanding are gums, mucilage, essential oils, oleoresins, resins, phloem like saps, and latexes. Regardless of their commercial importance, in the aspect of biology, plant exudates are believed to be involved in plant defense mechanisms, but their roles still remain unclear. In this thesis, based on diverse experiments, many features of plant exudates were unveiled. Interestingly, even if plant exudates possess a broad chemical diversity, their specialized biological functions resulted in less variation of their metabolomes as compared with their bearing tissues. This lower variation indicates that plant exudates might partake of a general-broad defense against herbivores and pathogens in their bearing tissues. This defense involves both mechanical and chemical traits which might complement and modulate each other, eventually resulting in a chemo-mechanical defense layer. Of the diverse chemicals in plant exudates, terpenes are one of the most common metabolites in these saps. Show less
