The Stone Age begins with the first production of stone implements and ends with the first use of bronze. Since the chronological limits of the Stone Age are based on technological development rather than actual date ranges, its length varies in different areas of the world. The earliest global date for the beginning of the Stone Age is 2.5 million years ago in Africa, and the earliest end date is about 3300 BCE, which is the beginning of Bronze Age in the Near East.
There is evidence suggesting that the 2.5 million year limit for stone tool manufacture might be pushed further back. The reason is that the capacity of tool use and even its manufacture is not exclusive of our species: there are studies indicating that bonobos are capable of flaking and using stone tools in order to gain access to food in an experimental setting. Nevertheless, there are differences between the tools produced by modern apes and those produced by the early toolmakers, who had better biomechanical and cognitive skills and produced more efficient tools. The difference, however, is of degree, not of nature. In fact, the earliest tools pre-date the emergence of the Homo genus, and it is believed that some of the Australopithecines were the first tool makers.
In addition, some researchers have claimed that the earliest stone tools might even have an earlier origin: 3.4 million years ago. Although no stone tools that old have been found, some bones showing signs of striations and gouges have been found in Ethiopia, which might represent cut marks made with stone tools. This view, however, is not widely accepted: the marks have also been interpreted to be the result of crocodile predation or animal trampling.
The Stone Age is also divided into three different periods.
- Paleolithic or Old Stone Age: from the first production of stone artefacts, about 2.5 million years ago, to the end of the last Ice Age, about 9,600 BCE. This is the longest Stone Age period.
The main types of evidence are fossilized human remains and stone tools, which show a gradual increase in their complexity. On the basis of the techniques employed and the quality of the tools, there are several stone industries (sometimes referred to as “lithic” industries). The earliest of these (2.5 million years ago) is called Oldowan, which are very simple choppers and flakes. About 1.7 million years ago, we find another type of lithic industry called Acheulean, producing more complex and symmetrical shapes with sharp edges. There are several other types of lithic industries until finally towards the end of the Paleolithic, about 40,000 years ago, we see a “revolution” of lithic industries where many different types coexisted and developed rapidly. Around this same time, we also have the first recorded expressions of the artistic life: personal ornaments, cave paintings, and mobilary art.
- Mesolithic or Middle Stone Age: In purely scientific terms, the Mesolithic begins at the end of a period known in geology as the Younger Dryas stadial, the last cold snap, which marks the end of Ice Age, about 9,600 BCE. The Mesolithic period ends when agriculture starts. This is the time of the late hunter-gatherers.
Because agriculture developed at different times in different regions of the world, there is no single date for the end of the Mesolithic period. Even within a specific region, agriculture developed during different times. For example, agriculture first developed in Southeast Europe about 7,000 BCE, in Central Europe about 5,500 BCE, and Northern Europe about 4,000 BCE. All these factors make the chronological limits of the Mesolithic somehow fuzzy. Moreover, some regions do not have a Mesolithic period. An example is the Near East, where agriculture was developed around 9,000 BCE, right after the end of the Ice Age.
During the Mesolithic period, important large-scale changes took place on our planet. As the climate was getting warmer and the ice sheets were melting, some areas in the northern latitudes rose as they were being freed from the weight of the ice. At the same time, the sea levels rose, drowning low-lying areas, resulting in major changes in the land worldwide: the Japanese islands were separated from the Asian mainland, Tasmania from Australia, the British Isles from continental Europe, East Asia and North America became divided by the flooding of the Bering Strait, and Sumatra separated from Malaysia with the correspondent formation of the Strait of Malacca. Around 5,000 BCE, the shape of the continents and islands was very much those of the present day.
- Neolithic or New Stone Age: begins with the introduction of farming, dating variously from c. 9,000 BCE in the Near East, c. 7,000 BCE in Southeast Europe, c. 6,000 BCE in East Asia, and even later in other regions. This is the time when cereal cultivation and animal domestication was introduced.
In order to reflect the deep impact that agriculture had over the human population, an Australian archaeologist named Gordon Childe popularized the term “Neolithic Revolution” in the 1940s CE. Today it is believed that the impact of agricultural innovation was exaggerated in the past: the development of Neolithic culture appears to have been more gradual rather than a sudden change.
Agriculture brought major changes in the way human society is organized and how it uses the earth, including forest clearance, root crops, and cereal cultivation that can be stored for long periods of time, along with the development of new technologies for farming and herding such as plows, irrigation systems, etc. More intensive agriculture implies more food available for more people, more villages, and a movement towards a more complex social and political organization. As the population density of the villages increase, they gradually evolve into towns and finally into cities.
Towards the end of the Neolithic era, copper metallurgy is introduced, which marks a transition period to the Bronze Age, sometimes referred to as Chalcolithic or Eneolithic era.
Tools and weapons during the Stone Age were not made exclusively of stone: organic materials such as antler, bone, fibre, leather and wood were also employed. The archaeological record, however, is biased in favour of items made of stone because these are far more durable than the organic materials, which are easily obliterated by the many processes of decay that they are subject to and can only survive under rare circumstances such as cold temperatures or very dry climate. Other durable materials such as copper and glass-made items have also survived. Under rare circumstances, plant, animal, and human remains have also managed to survive, sometimes merely fossilized, but other times they still present part of the soft tissue such as the several frozen specimens of the extinct woolly rhino and woolly mammoth that have survived in Siberia virtually intact.
Clay is another material which is abundant in the bulk of Stone Age material remains. Clay can be fashioned into a desire shape and baked to fix its form. This is the birth of pottery. Usable clay is widely available, which explains why pottery was independently invented in many parts of the world at different times. The oldest evidence of pottery manufacture has been found in an archaeological site known as Odai Yamamoto, in Japan, where fragments from a specific vessel have been dated to 16,500-14,920 BP (“before present”, meaning 16,500-14,920 years ago, usually associated with radiocarbon dating). Non-agricultural Jomon peoples of Japan were producing clay pots that were elaborately decorated by about 13,000 BP, which were used for food preparation.
During the Early Neolithic era, around 8,000 BCE, special ovens used to parch cereal grains and to bake bread were being built in the Near East, which allowed people to control fire and produce high temperatures in enclosed facilities. Initially, pottery was made in open fires, but the use of ovens added new possibilities to the development of pottery. Around the same time, some areas of South America were also developing pottery technology.
With the introduction of Bronze metallurgy, the Stone Age came to an end. Bronze is a mixture of copper and tin, which has greater hardness than copper, better casting properties, and a lower melting point. Bronze could be used for making weapons, something that was not possible with copper, which is not hard enough to endure combat conditions. In time, bronze became the primary material for tools and weapons, and a good part of the stone technology became obsolete, signaling the end of the Stone Age.