History and Impact of Tool Development
The First Tools
A tool is any device capable of multiplying the intensity or energy efficiency of the arm. The development of tools progressed through various stages:
- Stone carving (Australopithecus)
- Stone shaping (Homo habilis)
- Advanced stone tools (Homo erectus)
Homo sapiens revolutionized tool construction, using bone, wood, amber, and other materials to create needles, punches, harpoons, and scrapers.
Metals
Around 12,000 years ago, humans discovered how to cast metals from ore. The first metals obtained were copper, tin, and silver, which were easily bent or broken.
- Around 3000 BC, early bronze objects (copper + tin) appeared in Anatolia.
- In 2000 BC, the Hittites used iron for weapons due to its hardness and resistance, although it required high temperatures to melt.
- Later, steel, a more flexible and resistant material, was obtained by mixing iron with charcoal. This led to the emergence of forging and blacksmiths.
The discovery of bronze and iron led to a more complex and specialized society, contributing to the rise of new empires and the Industrial Revolution.
In the 19th century, aluminum emerged as a new material.
The Age of Plastics
While anthropologists define the Stone, Bronze, and Iron Ages, our current era could be considered the Age of Plastics, given its ubiquitous presence in clothing, furniture, and everyday objects.
The discovery of plastics resulted from the efforts of numerous scientists and engineers seeking to replace traditional materials. However, the reliance on oil and the challenges of waste management pose significant negative effects.
Polymers
A polymer is a large molecule composed of repeating elementary units called monomers. Plastic is a synthetic polymer made of elements like carbon, hydrogen, oxygen, nitrogen, phosphorus, sulfur, chlorine, and fluorine.
There are different types of polymers:
- Natural: Produced by biological processes (e.g., keratin, chitin, waxes, resins)
- Artificial: Derived from natural materials through transformation processes (e.g., rubber)
- Synthetic: Created through industrial processes (e.g., plastics)
Evolution of Plastic
- Before the conquest of America, latex was extracted from trees in Brazil to make rubber balls. European settlers used it as an eraser.
- In 1839, Charles Goodyear heated rubber with sulfur, creating vulcanite or ebonite, a hard, elastic, and durable material used for tires and other objects.
- In 1864, Alexander Parkes created parkesine (cellulose + nitric acid). John Hyatt later improved and patented the formula as celluloid, used for billiard balls, table tennis, combs, toys, and film.
- In 1905, celluloid led to the development of artificial silk and cellophane.
- In 1907, bakelite, the first synthetic plastic, emerged.
Lifecycle of Objects
The lifecycle of an object or material encompasses its journey from creation to disposal. Each stage involves inputs (resources used), outputs (waste generated), and environmental or social impacts.
The cost of a product includes internal costs (production and distribution) and external costs (gas production, air pollution, scrap).