Stone Age to Iron Age: Evolution of Materials and Technology
Stone Age
Materials Used in the Stone Age:
Paleolithic inhabitants made their first tools from a limited variety of rocks and minerals. These materials shared certain properties: hardness, toughness, fragility, and a conchoidal fracture. The variety in composition led to compounds, in some areas, with silicon. Siliceous materials were accessible where limestone was not present. The first tools were crude, but later the technique was perfected, resulting in more complex and useful tools. Fire was discovered during the Paleolithic era. This allowed humans to move from simple and poor exploitation of nature to enabling its transformation. Homo sapiens, reaching the apogee of Paleolithic technology, developed carving techniques. Other materials used included bone, wood, and ivory in the manufacture of various instruments. In the Neolithic period, stone was still used in increasingly sophisticated instruments. Ceramics were invented by calcining clay at over 400 degrees. People started taking advantage of bitumen, using it as a waterproofing agent and adhesive. Another material used as an adhesive was collagen, obtained from animal bones. Plant fibers were also used for various purposes.
Metal Age
The Stone Age ended with the Neolithic period, beginning the age of metallurgy, a technological advance that would define the new cultural era.
- The first phase is termed the Chalcolithic, in which copper was discovered and began to be worked.
- The second stage is the Bronze Age, when alloys of copper and tin began to be made.
- Finally, the Iron Age developed.
Working with the First Metals
The first metallurgy of copper occurred in closed ovens after using charcoal in Mesopotamia. Gold, known since ancient times, also began to be worked in this era. Due to its malleability, it was used to make rings and necklaces without actually melting it. Silver, used in antiquity, was much rarer than gold in Egypt.
Bronze
Bronze is the result of the alloy of copper and tin. It improves the properties of copper because it has higher hardness and a lower melting point. These features meant that bronze was used for 2,000 years for the manufacture of weapons and other utensils. Egyptians discovered, through observation, that it gave better results. In this era, a metal harder than bronze was discovered. When pieces of this metal were beaten, arms were obtained that were harder and stronger than bronze and that, in addition, maintained their edge longer. The first iron used by our ancestors came from meteorites. It was alloyed with nickel and cobalt, making it much harder than bronze.
Iron
While iron is very abundant in nature, it is mined in more complicated ways than copper, needing temperatures of 1,536 degrees Celsius. Pure iron contains less than 0.008% carbon and is a soft, ductile, and malleable metal. When we refer to useful iron, we are talking about iron alloyed with carbon, that is, steel, which melts at a lower temperature of 1,145 degrees Celsius. The discovery of iron technology occurred in 1500 BC and is attributed to an Armenian tribe, who immediately passed it on to the Hittites.
New Needs, New Materials
- The achievements of metal would result in the conquest of wood. There were no real homes with timber until instruments for cutting and sawing trees were developed.
- In the age of metals, another important material was discovered: glass. It is believed that the art of making glass originated in Syria and Egypt. Egypt produced glass using a mixture of quartz sand, lime, and natron. The use of iron allowed for the development of other forms of working glass. For example, iron pipes made it possible to blow molten glass. This could not be done with copper. Instead, iron’s low thermal conductivity and high melting point allowed the craftsman to work without burning (bottles, cups).
- In the year 20 BC, a Roman architect described the concrete method that would be used for many years.
- Humans were experimenting with polymers that were in nature.