An ancient engineering problem
At the Neolithic settlement of Hacılar in southwestern Turkey, occupied as early as 7040 BCE, people faced a persistent materials challenge. The invention of pottery allowed for better food storage and new cooking methods, but clay pots had a critical flaw: they often cracked when placed over a fire. This phenomenon, known as thermal shock, happens when rapid temperature changes cause different parts of a material to expand or contract at different rates, creating immense internal stress. For the inhabitants of Hacılar, a cracked cooking pot could mean a lost meal. Over generations, they developed a solution that demonstrates a sophisticated empirical understanding of material properties.
The potters began to intentionally mix organic materials—such as chopped straw, grasses, or animal dung—into their clay before shaping the vessels. During the firing process, as the clay hardened, this organic "temper" would burn away completely. The result was a ceramic matrix filled with a network of tiny, interconnected voids or pores where the plant fibers used to be. This network of pores was essential to their innovation.
Microscopic crack arrestors
The porous structure created by the burnt-out temper dramatically increased the pottery's resistance to thermal shock. When a micro-crack formed on the surface of a pot during heating, its propagation was stopped when it encountered a pore. The void dissipated the crack's energy, preventing it from spreading through the entire vessel wall and causing catastrophic failure. This process, known as crack deflection or crack bridging, is a principle in modern materials science for creating tough, fracture-resistant ceramics.
The potters of Hacılar did not have scanning electron microscopes, but through observation and experimentation, they learned to control the microstructure of their ceramics. This innovation made their cooking pots more durable and reliable, a significant technological advantage for a developing agricultural society. Excavations at Hacılar, led by archaeologist James Mellaart starting in 1957, unearthed large quantities of this distinct pottery, much of which is now housed in the Burdur Archaeological Museum. The artifacts from levels dating to the 6th millennium BCE show high-quality painted ceramics, indicating a mature and well-established craft.