Texts about prehistory are liable to use three different timelines or naming systems interchangeably so it’s as well to be absolutely clear about them. What follows isn’t definitive, it’s the opposite. It’s my attempt to make sense of the timelines and period-related terminology used in the Stonehenge exhibition at the British Museum. As far as I can tell there are three systems:

1. the geological eras
2. the sequence of ice ages
3. the archaeological periods relating to human culture

1. Geological eras

The geologic time scale is the very high level division of earth history into units called — in descending order of duration — eons, eras, periods, epochs and ages. We are interested in just two epochs:

a) The Pleistocene epoch: 2,580,000 to 11,700 years ago

This long period includes all the earth’s most recent periods of glaciations. It ends with the end of the most recent ice age and general climate warming.

b) The Holocene epoch: 11,650 to now

The Holocene is said to have started about 11,650 years ago, at the end of the most recent maximal glaciation or ice age, and we are still living in it today (although see the note at the end about the possible creation of a new epoch, Anthropocene).

Human figurines carved from yew wood with quartzite eyes from Roos Carr, East Yorkshire, 1000 to 500 BC © Hull Museums

2. Ice ages

The Quaternary glaciation: 2,588,00 YA to the present

The Quaternary glaciation started around 2,588,000 years ago (YA) and is ongoing. The dating of its start is based on the formation of the Arctic ice cap. The Quaternary glaciation itself consists of a sequence of glacial and interglacial periods and we are living in the most recent of its interglacial periods i.e. a warm spell between ice ages.

The Last Glacial Period (LGP): 115,000 to 12,000 YA

The Last Glacial Period (LGP), known colloquially as the last ice age, covers the period 115,000 to 12,000 years ago. The LGP is just part of the larger sequence of glacial and interglacial periods known as the Quaternary glaciation (see above). During this last glacial period there have been alternating episodes of glacier advance and retreat.

Last Glacial Maximum (LGM): 33,000 to 12,000 YA

The most recent period of glacier advance, when ice reached its furthest extent, is called the Last Glacial Maximum (LGM). Ice sheets covered much of North America and Northern Europe leading to a large drop in sea levels. The ice sheets began to grow 33,000 years ago and maximum coverage was reached between 26,500 and 20,000 years ago. At this point all of Scotland, most of Ireland and Wales and England north of a line from the Wash to the Bristol Channel was under ice. South of the ice the land was covered by permafrost with scattered glaciers and ice sheets at high points further south.

During the last glacial maximum, 26,500 and 20,000 years ago, the sea level was about 125 meters (about 410 feet) lower than it is today. After about 20,000 years ago deglaciation commenced in the Northern Hemisphere, and the ice cap began to retreat north, causing sea levels to rise.

The Holocene: 11,650 YA to the present day

Relevant both as a geological epoch and in the timeline of glaciation, the Holocene is the most recent geological epoch and the one we’re all still living in today. In Britain it correlates to the withdrawal of the ice sheets from the entire country.

As the ice sheets withdrew, Britain continued to be part of the continent of Europe, joined by an extensive area referred to as Doggerland. With the withdrawal of the ice and the rise of sea levels, Doggerland was flooded, creating what we now call the North Sea and the English Channel, a process which was complete by about 8,000 years ago.

Bone-bead necklace, part of the finds from Skara Brae, c. 3100 to 2500 BC Skara Brae, Orkney, Scotland © The Trustees of the British Museum

3. Human culture timelines

Human archaeology and ethnography uses what is called the ‘three age’ system, dividing the prehistory of humans into three broad categories – stone age, bronze age, iron age – according to the type of tools found in find sites.

It’s surprising to learn that this schema is 200 years old. It was developed by Christian Thomsen, director of the Royal Museum of Nordic Antiquities in Copenhagen, Denmark, in the 1820s. Thomsen wanted to categorise objects in his collection chronologically according to the main medium used for tool making in each era, and his collection suggested that stone tools came first, then bronze, then iron.

In 1865 the British archaeologist and ethnographer John Lubbock sub-divided the stone age into two, the old stone age or paleolithic (from the Greek paleo meaning old and lithos meaning stone) and the new stone age or neolithic (from the Greek neo meaning new and lithos). Almost immediately the British archaeologist Hodder Westropp suggested an intermediary stage, the middle stone age or mesolithic (from the Greek meso meaning middle and lithos meaning stone), which is still used but is a little more controversial.

Finally, it was realised that the huge extent of the so-called ‘paleolithic’ itself needed to be subdivided, eventually into 3 stages, the lower, middle and upper, which were proposed in the 1880s. And so we find ourselves with the following schema:

1. Stone Age: 
   • Paleolithic 3.3 million years ago to 15,000 YA
     • Lower Paleolithic: 3 million to 300,000 years ago
     • Middle Paleolithic: 300,000 to 30,000 years ago
     • Upper Paleolithic 50,000 to 12,000 YA
   • Mesolithic: 15,000 to 5,000 years ago
   • Neolithic: 5,000 to
2. Bronze Age 5300 years ago to 3200 YA
3. Iron Age to (depends on region)

Two reservations

1. It’s worth emphasising that this entire system works well in Europe and some parts of Asia but doesn’t far at all with human developments in Africa, the Americas or far Asia. In many parts of the world there was no Iron Age at all, for example in Pre-Columbian America and the prehistory of Australia.

2. The term Megalithic does not refer to a period of time, but only describes the use of large stones by ancient peoples from any period.

Now let’s look at the ages in a bit more detail:

Fine jadeitite axe-head made from material quarried in the high Italian Alps, c. 4500 to 3500 BC © The Trustees of the British Museum

Paleolithic or Old Stone Age: 3.3 million years ago to 15,000 YA

Paleolithic indicates the fact that from the dawn of the first proto-humans who used any kinds of tools through to the discovery of metal smelting, all human species used tools made from stone, particularly flint blades and axes. The paleolithic covers a vast period of time, from the earliest known use of stone tools by hominids c. 3.3 million years ago to the start of the Holocene era, about 12,000 years ago. It covers 99% of the period of human technological prehistory. For that entire period humans appear to have been roaming bands of hunter-gatherers living off the land.

As mentioned, as long ago as the 1880s it was found necessary to subdivide the Paleolithic into three:

Lower Paleolithic: 3 million to 300,000 years ago

The Lower Paleolithic is the earliest subdivision of the Paleolithic or Old Stone Age. It spans the period from around 3 million years ago when the first evidence for stone tool production and use by hominids appears in the archaeological record until around 300,000 years ago.

I was a bit puzzled by use of lower and upper until I equated this with the physical location of the finds with the older findings being literally lower down in the earth, and more recent findings being less deep or uppermost.

Middle Paleolithic: 300,000 to 30,000 years ago

The Middle Paleolithic is the second subdivision of the Paleolithic or Old Stone Age as it is understood in Europe, Africa and Asia. Anatomically modern humans (i.e. Homo sapiens) are believed to have emerged in Africa around 300,000 years ago. Around 125,000 years ago they began migrating out of Africa and slowly replaced earlier pre-existent Homo species such as the Neanderthals and Homo erectus.

The use of fire became widespread for the first time in human prehistory during the Middle Paleolithic and humans began to cook their food about 250,000 years ago.

The later part of the period saw the development of a range of new tools: about 90,000 years ago harpoons were invented which brought fish into human diets. Microliths or small stone tools or points were invented around 70,000 to 65,000 YA and were essential to the invention of bows and spear throwers.

Upper Paleolithic 50,000 to 12,000 years ago

The Upper Paleolithic or Late Stone Age is the third and last subdivision of the Paleolithic or Old Stone Age. About 50,000 years ago there was a marked increase in the diversity of artifacts. In Africa, bone artifacts and the first art appear in the archaeological record.

The early modern humans who migrated out of Africa and into Europe about 50,000 years ago, commonly referred to as the Cro-Magnons, left sophisticated stone tools, carved and engraved pieces on bone, ivory and antler, cave paintings and Venus figurines.

The distinct species Homo neanderthalensis, which had first emerged in the fossil record 400,000 years ago and lived widely across Europe and Asia, continued to live for a very long time – as long as 10,000 years – alongside the new incomers Homo sapiens. Then, abruptly, Neanderthals disappear completely from the fossil record 40,000 years ago, leaving archaeologists to speculate about the reasons for their sudden disappearance to this day.

This upper paleolithic revolution which kicked off 50,000 years ago saw many innovations. It witnessed the first evidence of human fishing. New implements were invented: for example, the spear thrower (30,000 years ago), the net (around 29,000 YA), the bolas, the bow and arrow (30,000 to 25,000 YA). From this period date the oldest examples of ceramic art, for example, the Venus of Dolní Věstonice (about 29,000 YA). Members of the European early Upper Paleolithic culture known as the Aurignacian had even developed lunar calendars by 30,000 YA.

Human populations

A really important fact to grasp is that human populations during this period were tiny. The entire population of Europe between 40,000 and 16,000 years ago was probably somewhere 4,000 and 6,000 individuals.

Bronze Age sun pendant, 1000 to 800 BC © The Trustees of the British Museum

The Mesolithic (in Britain): 12,000 to 6,000 years ago

The Paleolithic is said to end with the end of the last ice age and the spread back into Europe of human communities which developed new tools and techniques. The period from the end of the ice age to the arrival of metal smelting 4,500 years ago was initially simply referred to as the Neolithic or new stone age because of the proliferation of new techniques.

But, as we’ve seen, archaeologists almost immediately felt the need to define an interim period between the end of the Old Stone Age and the final period of innovation – hence the creation of the term mesolithic, which refers to the final period of hunter-gatherer cultures in Europe and Western Asia, between the end of the Last Glacial Maximum and the Neolithic Revolution. In Europe it spans roughly 15,000 to 5,000 years ago.

Precise dating of the Mesolithic varies between areas because they were impacted by a) deglaciation and the creation of newly habitable land and b) the arrival of the agricultural revolution, at widely varying times. Thus the mesolithic is said to start in warm Greece around 15,000 years ago but in chilly Britain only around 12,000 YA.

Broadly speaking the Mesolithic is associated with a decline in the group hunting of large animals in favour of a broader hunter-gatherer way of life, and the development of more sophisticated and typically smaller lithic tools and weapons than the heavy-chipped equivalents typical of the Paleolithic.

The Neolithic (in Britain): 6,000 to 4,500 years ago (2,500 BC)

The Neolithic is now used to refer to the period after the ice age when human society was transformed by the advent of agriculture with its enormous cultural, social and economic consequences, but most tools continued to be made of stone, albeit of high levels of sophistication.

The advent of agriculture is sometimes referred to as the Neolithic Revolution. It saw the wide-scale transition of many human cultures from a lifestyle of hunting and gathering to one of agriculture and settlement, with the domestication and breeding of edible grasses and farm animals. With settlement came villages and then towns. We have religious records which point to polytheism.

Some archaeologists refer to a ‘Neolithic package’ in which they include farming, herding, polished stone axes, timber longhouses and pottery. Farming formed the basis for centralised administrations and political structures, hierarchical ideologies, depersonalised systems of knowledge (that’s to say, writing), densely populated settlements, specialisation and division of labour, more trade, the development of non-portable art and architecture and greater property ownership.

The agricultural revolution spread from its origins in the Middle East, through Turkey, across Greece and slowly into central and western Europe. Different sites in the Middle East point to different dates for the domestication of different plants or animals but the process was underway by as long ago as 12,000 years ago.

The diffusion across Europe, from the Fertile Crescent through Anatolia, across the Aegean and central Europe to Britain, took some 3,000 years (9500 to 6000 years ago). It is calculated to have spread at a speed of about 1 kilometre a year, but it was patchy, spreading to some (fertile) areas, moving round mountains, stalling, then suddenly jumping again.

Interestingly, there is evidence of some communities keeping to the mesolithic hunter-gatherer lifestyle for very long periods after the neolithic package arrived, for as long as a thousand years! Archaeologists call such societies are called ‘subneolithic’, the ‘sub’ just meaning hanging on after the main era had ended.

One of the mind-blowing aspects of the neolithic revolution is that all the evidence suggests it made human beings measurably worse off! Many of the cultivated crops (wheat, barley, maize) are deficient in vitamins and minerals and relying on them and cow or goat milk to the exclusion of other elements in a diet can be very harmful. All the archaeological evidence suggests that the Neolithic Revolution led to much more limited diets and poorer nutrition. Human height decreased by an average of 5 inches! Apparently human height didn’t return to pre-neolithic levels until the 20th century.

In addition, close habitation with animals led infectious diseases to jump the species boundary. Smallpox and influenza are just two diseases we got from animals. And higher population densities, living with poor sanitation led to tainted water supplies and the usual diseases of diarrhoea and dysentery, typhoid and cholera.

Jared Diamond suggests that the status of women declined with the adoption of agriculture because women in farming societies typically have more pregnancies and are expected to do more demanding work than women in hunter-gatherer societies.

Having read widely about it, it’s hard to avoid the conclusion that the Neolithic Revolution was a catastrophe for most humans.

The Bronze Age (in Britain): 2,500 BC to 800 BC

Bronze is produced by smelting copper and alloying it with tin, arsenic, or other metals to strengthen it i.e. use it to make stronger, more durable tools or weapons.

In Eurasia the development of bronze tools definitely follows the final refinement of stone ones, and supersedes them. When exactly this happened varies largely from region to region and even from site to site within regions.

In Britain the advent of the Bronze Age is generally agreed to be marked by the arrival of the so-called Beaker culture, so named for the sudden appearance of beaker- or bell-shaped bowls in graves. In Britain the Bronze Age is subdivided into an earlier phase (2500 to 1200 BC) and a later one (1200 to 700 BC).

The Beaker people appear to have known how to smelt copper from their first arrival but it is only around 2150 BC that there is evidence of them smelting copper with other metals (generally tin) to make bronze.

A 2017 study suggests that the Beaker People almost completely replaced the island’s earlier inhabitants, with an estimated 90% of Britain’s neolithic gene pool being replaced! That’s to say, the people who built Stonehenge were substantially wiped out and superseded.

Primarily the Bronze Age is characterised by the widespread use of bronze tools and implements. It is usually accompanied by most of the traits of ‘civilisation’, including craft, urban centres, crafting of precious objects, widespread trade. In the Middle East and Greece we know it was accompanied by the worship of ethnic gods.

Devon and Cornwall were major sources of tin for much of western Europe and the earliest Greek and Roman historians refer to trade with these remote islands which brought the ore to the Mediterranean heartlands.

Bronze twin horse-snake hybrid from hoard, 1200 to 1000 BC. Kallerup, Thy, Jutland, Denmark © National Museum of Denmark

The Iron Age (in Britain): 800 BC to 43 AD

The Iron Age in Britain is dated by the first finds of iron tools in burial sites (around 800 BC) to the arrival of the Romans (43 AD).

The Iron Age is characterised by substantial population growth which allowed increasing social specialisation in societies living in large settlements. In Britain there was a proliferation of large hill forts. There is sophisticated social organisation, for example a class system overseen by a king and the implementation of taxation. There is extensive trade, nationally and internationally, leading to burial sites rich in high value goods, sometimes transported across great distances.

Also a good deal of immigration with entire tribes moving into and settling territories. Whether this involved conquest or peaceful ‘diffusion’ is debated to this day. When the Romans arrived they found a land divided among tribes with a highly developed sense of identity, regional allegiance, names and kings.

The Iron Age is said to end when writing begins. Even though the same kinds of tools are used, a culture has clearly entered a new phase when it enters the historical record. But obviously this happened at different times in different regions.

Thus in the Ancient Near East the Iron Age is taken to end with the start of the Achaemenid Empire in the 6th century BC, as it enters history in the writings of the Greek historian Herodotus. In Western Europe the Iron Age is ended by the Roman conquest, which was established by 100 AD. By contrast in Scandinavia and other parts of northern Europe that the Romans did not reach, the Iron Age is said to have continued until the start of the Viking Age in about 800 AD.

As the Stonehenge exhibition at the British Museum strongly indicates, the later Iron Age was characterised by increasing warfare and social strife. Skeletons show signs of multiple injuries. Average life expectancy at birth was around 25. Into this culture arrived the Romans with their writing, education, towns, roads and laws.

P.S. A new geological era – the Anthropocene?

Remember how I said we’re only interested in two geological epochs, the Pleistocene and the Holocene. Well, there is a new, third category: many scientists are pushing for the scientific community to recognise that the Holocene has ended and we have entered a new epoch, to be named the Anthropocene.

The idea is that this new era should be dated to mark the commencement of significant human impact on Earth’s geology and ecosystems. With widespread acceptance that manmade global warming is having (and will continue to have) a significant effect on the world’s ecosystems, you can see the logic of arguing that we live in an entirely unprecedented era. But to date, none of the official bodies which recognise the geological eras have accepted the anthropocene and there is ongoing debate about when  it should be said to have started.

The problem with our over-documented, over-determined time is that too much has happened. Since Hiroshima we live in The Atomic Age. And since the end of the Second World War we are also all living in an age of rapid technological and social change, which some historians call the Great Acceleration.

Or should we be going further back, should the start of the anthropocene be lined up with the start of the Industrial Revolution in 1710 or 1770 (depending on which precise technical discoveries you prioritise)?

Or, in a massive leap, should we go right back to the start of the neolithic revolution described above, which is when human beings first began to have a measurable impact on their environment? Which would make it identical the current term, the Holocene?

The debate is ongoing and there’s no shortage of candidates but if we stick to permanent markers which are being laid down now and which geologists will find in a million years time, then apparently radioactivity from the nuclear tests is now embedded in ice cores and a thin layer of microplastics has been laid down on the ocean beds, the kind of thing which 100% fulfil the geological criteria.

Personally I think it should be the 1780s and the invention of new, more efficient steam engines, as it was this breakthrough – more than agriculture itself – which set us on the course of greater and greater reliance on energy, first coal, then oil and gas whose use, we all now know, has led to our runaway proliferation, our destruction of every ecosystem we come into contact with, and what looks likely to be massive and irreversible effects on the entire global climate.

Will Stonehenge, built as a result of the neolithic agricultural revolution, survive long enough to see the world transformed by the manmade global warming which is that revolution’s long-term legacy? (Photo © English Heritage)

Related links

• The world of Stonehenge runs until 17 July at the British Museum
• The Sixth Extinction: An Unnatural History by Elizabeth Kolbert (2014)
• Ice Age art: arrival of the modern mind (@ the British Museum, March 2013)
• The Origin of Our Species by Chris Stringer (2011)
• Guns, Germs and Steel by Jared Diamond (1997)
• The Sixth Extinction by Richard Leakey and Roger Lewin (1995)