Dateline 2010: the world-historical situation

In the twilight century of western civilisation, the US, the last resting place of western power, has as its primary purpose the containment of rising China. China has as its primary purpose to put the world 'back to rights'. It is playing a waiting game, and is anxious not to jump the gun.

Dark Age Watch (DAW on hold.)

Issue du jour 1: War with Iran--important to containing China but delayed over two years

Issue du jour 2: The world economy--unbalanced, interwoven, delusional--some predict its unravelling

Issue du jour 3: Somalia--leading the world into a dark age

Issue du jour 4: Pirates exploit the decline of international order

Thursday, 15 October 2009

Technological evolution

We need a measure of technological sophistication.

Technology changes through history, and technological sophistication is closely related to scale and societal eigenmode.

The internet, for example, makes possible and is made possible by the high scale of the modern world.

  • It should be obvious that the internet makes the modern world possible. Consider the direct impact on many businesses if their web and email facilities were suddenly shut off, and consider the indirect impact on many others.
  • As for the modern world making the internet possible, imagine a group of, say, a hundred idealists who decide to cut themselves off on a desert island. Could they produce or maintain all the familiar internet facilities like Google, Amazon and Wikipedia? Obviously not. Even if they took this technology with them, they would soon fall behind what was happening in the outside world, where thousands, even millions, of people are continually advancing the relevant services and underlying software.

In order to talk comparatively about technological change, we need a uniform way of describing the degree of sophistication of any given technology. This has to be applicable to everything from a stone axe to a Saturn V rocket and beyond.

Technological sophistication reflects four factors relating to the creation of an artefact instantiating that technology:
  1. The sophistication of the inputs or precursor processes and materials.
  2. The amount of effort needed for preparation (e.g. assembling the materials in one place).
  3. The amount of effort needed for actually producing the artefact.
  4. The amount of skill required.

The higher the skill, the higher the effort of preparation and production, and the higher the sophistication of precursors or inputs, the greater the sophistication of the technology.
  • A crude stone axe requires no input except a stone, which is about as unsophisticated as one can get, and minimal preparation. It may take some skill but this is relatively easily acquired, and the process of production may involve only a few minutes of effort.
  • A space rocket has very sophisticated inputs, including specialist plastics and alloys, complex microelectronics, and a large ground-based infrastructure for mission control. Preparation and production may take many years of effort by many people, and they will be drawing on an extensive education, from kindergarten through university to specific on-the-job training.

We can reduce the four factors to a common form by considering them in terms of time resources (also known as effort), i.e. the number of people involved in each activity multiplied by the amount of time each person contributes. Specifically, we define technological sophistication as equivalent to total time resources to produce the artefact:
t = tm + tp + ts +

t = total time resource to produce artefact ( ≡ technological sophistication)
tm = time resource for actually making the artefact
tp = time resource for preparation
ts = time resource for skill acquisition
ti = total time resource to produce input i ( ≡ technological sophistication of input i)

Technological sophistication therefore has units of person-seconds (or equivalently person-hours, person-days, person-years, whichever is most suitable). Note that technological sophistication is a characteristic of an artefact, not of a society or of a period in history.

Technological sophistication can be thought of as the amount of time it would take one person, starting from scratch, to manufacture the artefact in question, including all its precursors and materials. If the artefact were, for example, a Saturn V, the person would have to begin by learning basic geology and making a spade or pick in preparation for mining the ore to produce the metal from which the rocket's parts would eventually be constructed. The technological sophistication of the rocket could amount to many human lifetimes.

The actual time resources going into the creation of an artefact are not, in general, equal to the theoretical time resources used in the above definition of technological sophistication. This is because few artefacts are made starting from scratch. Instead, effort is amortised over many artefacts.
  • For instance, once a digger is available for mining ore, it can be used on many projects, not just to produce the one Saturn V. The time resources absorbed by producing the digger are in reality shared across many projects, and the Saturn V is responsible only for a small fraction of that effort.
  • Similarly, if multiple copies of an artefact are produced, the effort for skill acquisition, and possibly some of the preparation, does not need to be repeated. The skill acquisition and preparation time resources per artefact are therefore a fraction of what they would be for just one artefact.

Nevertheless, it makes sense to define technological sophistication as if one were starting from scratch while producing only enough of everything to manufacture one final artefact, even though that does not happen in practice. It is this definition that gives the truest account of what goes into making an artefact.
  • Consider writing a letter on a computer versus writing it with quill pen and parchment. The effort involved in each case may be about the same (e.g. it could take an hour to produce the letter either way). This is also true of preparation (switching on the computer, trimming the quill pen) and skill acquisition (learning to type, learning proper calligraphy)--the effort may be about the same in each case. Even the time resources devoted to the inputs might be similar if the time to build a computer is about the same as the time to prepare a piece of parchment from animal skin. Therefore, if we considered only the actual time resources going into the modern and medieval letters, there would seem to be no difference in technological sophistication. However, there obviously is a big difference in technological sophistication, which is reflected in the fact that a lot more effort and knowhow went into the development of the modern computer than ever went into the development of parchment and quill pens. This is what our definition of technological sophistication captures by assuming one starts absolutely from scratch.

  • Consider also that one person probably could produce a parchment letter from scratch (e.g. starting by tanning the goatskin and mixing soot and egg white to make the ink* etc.). However, to make a computer starting from scratch (i.e. beginning at the level of mining the ore) would take a lifetime, or probably several lifetimes. The time resources going into a computer are so high that, to make computers feasible/affordable, the time resources have to be amortised over many units, both for the final artefact and for the components from which it is built. This industry can only survive if it is done on a large scale, serving a large customer base. In this respect, medieval society was neither populous nor connected enough to support computing, and parchment-based letter writing technology was all that was feasible.
*This is merely illustration, not an accurate description of how to make medieval ink.
To demonstrate this definition of technological sophistication, I will calculate the changing sophistication of cutting tools, from the stone age onwards.
I cannot provide absolutely accurate values of technological sophistication, especially for the more complex technologies. This would require a vast amount of research. The figures given below are only estimates. My main purpose is to show the definition of technological sophistication in practice.

The first cutting tools used by humans were made of stone (=lithics). The tools of the palaeolithic and mesolithic (old and middle stone ages) can be classified into five lithic modes, reflecting increasing levels of sophistication (see Grahame Clark, World prehistory: a new outline, 2nd edn [1969]). The cutting tools of the neolithic (new stone age) were of higher sophistication again. After this came the successive increases in sophistication of copper, bronze and finally iron or steel tools.

Mode 1 stone tools involve the creation of a cutting edge by the application of a few sharp blows from another stone. This requires skill, but not much effort, and little attention is paid to the final form, which is rough and ready. The tool may either be the stone or one of the flakes chipped from it. Sometimes the tool is 'retouched' by chipping off a few small flakes to restore a cutting edge after it has been blunted or broken in use.
Mode 1 stone tools: typically prepared with just a few blows, ad hoc in size and shape

Mode 1 tools were already in use with early hominids in Africa, 2.5 million years before the appearance of modern humans. Some of the tools used by Australian aborigines, who are fully modern humans, continue to belong to this most basic category.

-- Sophistication estimate --

FactorDiscussionTime resources
Skill acquisitionTen minutes to pick up the basic technique, though performance would improve with practice600
Preparation5 minutes to select a suitable stone and hammer stone. Any kinds of stone lying around would be suitable, provided they were of reasonable size and shape.300
Manufacture1 minute to knock off a few chips60
TOTAL≈ 1000

Mode 2 stone tools require at least twice as many blows as a Mode 1 tool, and they are made to take a definite, standardised, symmetrical form, that of the classic hand axe. Instead of chipping with another stone, a soft implement of wood, antler or bone is typically used, often with pressure flaking, to provide fine control over the shape. The removed flakes are not used.

Mode 2 stone tools: chipped all the way round with a soft hammer (wood, bone) to achieve a definite symmetrical form, requiring at least a dozen blows

Mode 2 tools were in use with pre-human hominids from about 1.5 million years before the emergence of humans. The technology developed in Africa and was carried into Europe and Asia by the pre-human hominids that colonised these regions from around 1 million years ago. Again, Mode 2 tools have continued in use with the Australian aborigines.

-- Key innovation --

Specialised ancillary tool (wood etc. hammer); aim of producing a repeatable, pre-conceived form.

-- Sophistication estimate --

FactorDiscussionTime resources
InputsThe bone/wood/antler flaking tool needs to be sourced and prepared, cutting it to the right length and maybe shaping it a bit. Perhaps twenty minutes.1200
Skill acquisitionIt should be possible to get the technique (from sourcing the stone and flaking tool to the design of the axe) in an hour.3600
PreparationA more specific size, shape and type of stone is required. Going to a likely site and selecting a suitable stone might take about half an hour.1800
ManufactureMore blows are required and more careful attention, in order to get the symmetrical shape. Perhaps 5 minutes.300
TOTAL≈ 7000

Mode 3 stone tools involve the Levallois technique, in which a stone core is first carefully prepared and then a single large flake is struck off from it with a sharp blow. In contrast to Mode 2, where the shape emerges gradually, allowing some trial and error, this technique requires a thorough understanding of how flint fractures and an ability to picture in advance the flake that will be produced. Preparation of the core requires a hundred or more shaping blows before the final blow that removes the flake. However, the precise shape of the flake is not particularly standardised.

Mode 3 stone tools: struck with one movement from a carefully prepared core, requiring around a hundred preliminary blows along with the expertise and imagination necessary to envisage how the stone will fracture at the last critical blow

Mode 3 tools are associated with the near-human Neanderthals and were in use from about 200,000 years ago. The first modern humans also sometimes used Mode 3 tools, and indeed the Australian aborigines have never used anything more than Mode 3.

-- Key innovation --

Extensive preparatory work during which finished item is not apparent.

-- Sophistication estimate --

FactorDiscussionTime resources
InputsAgain a special tool is used for flaking. To prepare it: twenty minutes.1200
Skill acquisitionA period of practising more basic techniques would be needed to develop the necessary understanding of stone's characteristics. One 8-hour day.28,800
PreparationSpecial types of stone, similar to Mode 2, would be required. Fetching time: 1 hour3600
ManufactureA long period of shaping the stone is required before striking off the final product: 10 minutes600
TOTAL≈ 35,000

Mode 4 stone tools are based on long, narrow blades with two sharp edges. These are struck from a core whose preparation is more complicated than for Mode 3, requiring some 250 blows with a bone rather than stone hammer, but then yielding five times as many tools from one block of stone. Blades are also versatile. For example, one edge may be blunted, to create a scraper, or the blade may be shaped into a burin, which has a sharp point and can be used to gouge holes in other materials.

Mode 4 stone tools: struck successively from a prepared core, having long sharp edges and possibly further shaped into specialised tools such as the burin (right), used for drilling holes

Mode 4 tools came into use among fully modern humans at the beginning of the Upper Palaeolithic, i.e. G 1 (c. 50,000 years ago). Whereas Mode 3 tool users stuck to stone almost exclusively, blade tools are associated with equal numbers of tools made from bone and antler. Only modern humans used Mode 4 tools, but not all modern humans used them, since the Australian aborigines and some extinct cultures of Southeast Asia never did.

-- Key innovation --

Preparatory work to produce savings downstream as many blades can be mass-produced from one core; creation of tools to make tools (e.g. burin is used for making holes in bone/ivory to produce needles).

-- Sophistication estimate --

FactorDiscussionTime resources
InputsAgain a specialist hammer: twenty minutes1200
Skill acquisitionMuch practice is needed for genuine competence: two 8-hour days57,600
PreparationGreater care is needed in selecting the best stone (flint or similar). This might take a day (8 hours) to fetch. In reality, stone might be traded so that people would not have to find it themselves, but this is the sort of efficiency saving we ignore in the calculation of technological sophistication28,800
ManufactureThe preparation of the core requires 250 blows and the blade is further refined after being struck: 25 minutes1500
TOTAL≈ 90,000

Mode 5 stone tools consist of microliths, i.e. small flakes of around an inch long, or less. They come in many precise forms, including triangle, rectangle, rhombus, trapezium, crescent and leaf-shape. They are not complete in themselves but belong to composite tools, such as knives, sickles, spears, harpoons and arrows, with several microliths being fixed into a bone or wooden handle or shaft using resin and possibly some kind of fibre.

Mode 5 stone tools: tiny microliths, chipped into precise shapes and stuck into wooden or bone handles/shafts, using resin and fibre, to produce composite tools such as an arrow (left, with trapezoid head) or harpoon (right)

Mode 5 tools appeared in Africa and India around G 475-875 (40,000-30,000 years ago). By G 1275-1675 (20,000-10,000 years ago) they were in use almost everywhere. There was, however, much more variation than for Modes 4 and below, with groups only a hundred miles apart favouring different shapes and styles of microlith. The greater sophistication of Mode 5 technology is also apparent from the way they were associated with simple 'machines' multiplying human muscle power, namely the bow and the spear thrower, both of which were in use by G 1475 (15,000 years ago, the bow may have been in use much earlier).

-- Key innovation --

Complex composite tools, themselves part of compound systems (e.g. bow and arrow).

-- Sophistication estimate --

FactorDiscussionTime resources
InputsThe inputs are finished stone blades (the microliths). I will assume these have the technological sophistication calculated above for Mode 4 (90,000). Another input is string, for which I will conservatively assume a technological sophistication of 8 hours118,800
Skill acquisitionTraining is needed in sourcing resin, carving a stick to the right size and shape, and hafting the microliths to it. 8 hours28,800
PreparationObtaining the resin and a suitable stick (the string and microliths are already available, having just been made). Half an hour.1800
ManufactureCarving the stick and attaching the microliths. Half an hour.1800
TOTAL≈ 150,000

Neolithic stone tools involve the imposition of a preconceived shape on a piece of stone. This is either by minutely detailed chipping, to create arrowheads and daggers, or by polishing, to create axes and hammers. In both cases, the form transcends the material of which it is made, in the sense that the object's function, rather than the behaviour of stone, is the primary driver. One is looking at an object that happens to be made of stone, rather than at a stone that has been hacked into a useful shape.

Neolithic stone tools: (not to scale) standardised forms determined by the intended function rather than by the properties of the stone, and involving either minutely detailed chipping to create arrowheads (left) and daggers (centre left), or polishing to create axeheads (centre right) and socketed axe-hammers (right)

Neolithic stone tools: (continued) a neolithic polished axehead, and the tool as it would have been used

The beginning of the Neolithic, and hence of tools like this, is synonymous with the beginning of farming around G 1600 (10,000 BC). The technique of polishing axeheads was perhaps suggested by the technique of grinding corn between two stones, where the stones became smooth as they rubbed against each other.

This technology emerged first in North Africa and the Middle East, and later in Europe, Asia and the Americas. It continued after the invention of metalworking, among people who could not afford or obtain metal tools. The above dagger dates from around G 1940 (1500 BC) and seems to have been inspired by bronze weapons.

Besides their practical purpose, polished axeheads had value as a medium of exchange and store of wealth. The clip below is of a hoard of axeheads found in a burial mound in Brittany, France, and shows they must have been produced in huge quantities.

-- Key innovation --

Form determined by function rather than by properties of underlying material.

-- Sophistication estimate --

FactorDiscussionTime resources
InputsA suitable block of stone would need to be prepared as a grinding platform (8 hours). Animal hide would need to be obtained (by hunting) and prepared for binding the axe in a tool (4 hours). An initial set of stone tools would be needed for the carving and cutting tasks associated with these and subsequent activities (assume sophistication of Mode 4 tools: 90,000 person-secs).133,200
Skill acquisitionThe basic grinding/polishing technique could be picked up quite easily, although to create sharp, smooth and symmetrical axes would require longer practice. 2 hours7200
PreparationThe hide is assumed available. Other parts to be sourced and fetched are: the stone to be polished, resin for gluing it in the handle, the handle itself, and one or more abrasives (sand) to be used in polishing. Total: 1.5 hours5400
ManufactureThe stone would be roughed out by chipping then polished by rubbing against the platform, using successively finer abrasives to get the final smooth surface (1 day). It would then be mounted in the handle (1 hour).32,400
TOTAL≈ 180,000

Copper tools are made either by beating the solid metal into shape or by melting it and casting it in moulds. In a very few places, such as parts of the North American Great Lakes, copper can be taken from the ground in virtually pure form. However, most of the time it has to be extracted from an ore by heating. It thus requires an extra stage of transformation compared to the shaping of a stone. Yet unlike a stone, the molten metal can be cast into arbitrary forms, and once a mould has been produced, identical copies can be turned out one after the other. Copper is also less brittle than stone and, if broken, can be melted down and recast. Since copper is not nearly as common as stone, the widespread use of copper requires long-distance exchange between producers and consumers. Typically, the ore is refined close to the mine location then transported in the form of standardised ingots.

Copper tools: the metal is either beaten into shape with a hammer (e.g. spearhead, left; note the groove round the hammer stone for attachment of a handle), or molten and cast in a mould (e.g. axehead, right); the resulting copper tool (centre, reconstruction) can be neater and more compact than its stone equivalent

Copper tools: (continued) this is a classic oxhide ingot of the ancient copper trade; the ingot is 27 inches by 16 inches (70 cm by 40 cm) and weighs around 82 lb (37 kg); it is a convenient shape for carrying by two people

Copper and gold were the first metals to be worked by humans, beginning in ancient Iraq around G 1760 (6000 BC). Copper was in common use in Europe and Egypt by G 1860 (3500 BC). The reconstructed copper axe above belonged to Ötzi, the man from G 1870 (3300 BC) whose body was found in an Alpine glacier in G 2080:16 (AD 1991). Copper chisels were used in the building of the Giza pyramids around G 1900 (2500 BC). This 'copper age', also known as the chalcolithic (chalcolithic = 'copper-stone'), technology does not seem to have reached sub-Saharan Africa until G 1960-1980 (1000 - 500 BC).

The discovery of copper metallurgy is related to the invention of pottery, which meant that people were already experimenting with heating earthy materials in a fire. Pottery, in turn, could have been suggested by the practice of heating stone tools to give them strength; this may have led people to experiment with the effects of heat on other materials.

-- Key innovation --

Transformation of raw material (ore) whose properties are not those of the finished product.

-- Sophistication estimate --

FactorDiscussionTime resources
InputsOne input is the copper ore. This requires developing some knowledge of geology (4 hours), and then the actual location and extraction of the ore (8 hours). A set of stone tools would be needed for this (assume Mode 4: 90,000 person-secs). There is also a need for a pottery crucible and charcoal for the fire: assume 8 hours to make these.162,000
Skill acquisitionIt is necessary to understand the construction of a cast and the melting and pouring of the copper. 12 hours.43,200
PreparationThe copper must first be produced from the copper ore. 8 hours.28,800
ManufactureA mould has to be made, then the copper poured. After the copper is removed from the mould, it requires tidying up and polishing. For this: 12 hours. Finally, the object needs to be mounted in a suitable manner: 4 hours.57,600
TOTAL≈ 290,000

Bronze tools are made from a mixture of typically 90 percent copper and 10 percent tin or arsenic. The metals are molten together and cast in a mould. Bronze is much harder than pure copper, and can hold a sharp edge. Tin-bronze is superior to arsenic-bronze, which therefore tends to be found only in early or less developed bronze industries. However, tin is even rarer than copper, so a tin-bronze industry presumes a well-developed trade network connecting the point where the ore is mined and refined with the regions where the bronze artefacts are to be produced.

Bronze tools: an alloy of copper and tin, bronze is strong than either and capable of carrying a sharp edge; varying sophistication is evident in both the amount of metal used and the complexity of the shape to achieve a given effect, here ranging from the flat axe (far left) to the same with small flanges that hold it more firmly in the handle (centre left), to the palstave axe with an attachment loop and shaped mounting area separate from the blade (centre right), and finally to the fully socketed axe (right)

The earliest bronze-working societies were in the areas of modern Turkey, Syria and Iraq, beginning around G 1860 (3500 BC). Bronze was in use in China by G 1912 (2200 BC), in north-western Europe by G 1930 (1800 BC), and in India and Egypt by G 1940 (1500 BC). In the Americas, metalworking, with gold, silver and copper, began around G 1980 (500 BC), and copper-silver and copper-gold alloys appeared around G 1993 (200 BC). Arsenical bronze did not appear until around G 2040 (AD 1000), and classic tin-bronze was only introduced by the Incas around G 2060 (AD 1475), shortly before the Spanish conquest. American pre-Columbian metalwork tended to consist of decorative and prestige objects, rather than tools or weapons.

Arsenic often occurs naturally in conjunction with copper, which would have facilitated the discovery of arsenical bronze and perhaps suggested the possibility of experimenting with other adulterating metals.

Styles of bronze artefacts evolved continuously, tending to become both more efficient and more mass produced in their appearance, as illustrated in the following clip.

I have participated in a couple of bronze-making workshops run by Dave Chapman. The first was to make a leaf-shaped sword based on one in the Pitt-Rivers museum; this was cast in a stone mould. The second was to make an early bronze age-style axehead, using the lost-wax technique.

Replica leaf-shaped bronze sword cast in stone mould

Replica early bronze age axehead made using lost-wax technique

-- Key innovation --

Combination of raw materials to produce substance not found in nature.

-- Sophistication estimate --

FactorDiscussionTime resources
InputsFor the ores, geology knowledge is required - more than for copper as there are now two metals involved, so 6 hours. For locating and mining the ores, two 8-hour days. Again there is a need for a set of stone tools (assume Mode 4: 90,000 person-secs), and for a pottery crucible and charcoal for the fire (8 hours).198,000
Skill acquisitionSimilar skills are needed as for copper, but now two metals are involved. Assume 50 percent more effort: 18 hours.64,800
PreparationThe metals need to be separately refined from their ores: 12 hours43,200
ManufactureThe actual melting and pouring of the bronze takes relatively little time, but there is much work first in creating the mould into which the metal will be poured and then in cleaning up and polishing the object after it has been removed from the mould. For this, two 8-hour days. Finally the object needs to be mounted in a suitably carved handle: 4 hours.72,000
TOTAL≈ 380,000

Iron tools are usually made from iron combined with small amounts of carbon (up to about 2 percent), and possibly with other elements, to create various kinds of steel. In terms of hardness and sharpness, decent bronze can actually be superior to an average piece of iron. On the other hand, deposits of iron ore are relatively common, which means that, compared to bronze, the technology is less reliant on far-flung trade networks, and this makes it cheaper. Iron has a higher melting point than bronze (around 1500°C compared to 1000°C), so that refining or casting it requires more sophisticated furnaces and handling equipment. However, the metal can be worked at lower temperature in a forge. A sword, for example, can be made from a bundle of rods heated and hammered together -- the metal becomes soft enough to take on a new shape, but does not actually melt. Iron can also be welded. This involves causing two pieces of metal to fuse by the local application of intense heat.

Iron tools: made from a metal that is widely available but only melts at high temperature (although becoming soft enough at lower temperatures to be worked in a forge); iron is usually mixed with small amounts of carbon, and sometimes other elements, to create various steel alloys; iron and steel remain in common use for a wide range of tools; here are shown an axehead of around G 1980 (500 BC) from the Black Sea region (top left), a replica Roman sword (left), a Roman axe (centre), a modern axe (right), and a chainsaw (bottom right)

Iron was first produced in the period after G 1920 (2000 BC), in India, the middle east and east Africa, but this was only in small quantities and as a kind of novelty. Around G 1960 (1000 BC), iron came into widespread use, overtaking bronze as the material of choice for tools and weapons. This occurred first in the middle east and Mediterranean countries from Egypt to Italy. In central Europe, iron technology took off 10 g later, i.e. around G 1970 (750 BC), and in north-western Europe 10 g later still, i.e. around G 1980 (500 BC). Iron technology also became fully established in sub-Saharan African in this same period, G 1960-1980. Africa was unusual in that iron and bronze came into use there at around the same time, instead of a lengthy bronze age preceding the take-up of iron. Iron was not known in the Americas until after the Columbian contact (G 2060:17 = AD 1492).

The addition of carbon to iron, to make steel, was a fairly natural development, since carbon would previously have been used in bronze casting, where it prevents a skin forming over the molten metal. The carbon came from charcoal (85-95 percent carbon), which is obtained by heating wood in the absence of oxygen and burns at the high temperatures needed for melting metal. In a primitive foundry, with a charcoal fire force fed by bellows, there would be plenty of carbon dust floating around in the air, and early metallurgists probably could not avoid it getting into the mix.

Over the generations, the technology of iron-making has evolved in several ways. One goal has been to allow iron to be handled in larger quantities, while another has been to adjust the amount of carbon and other elements so as to produce iron/steel with varying qualities (in terms of melting point, malleability, rust-resistance etc.) suitable for performing varying tasks. One major innovation, the Bessemer process, was made only just over 6 g (150 years) ago, and iron-making patents continue to be taken out to this day. Steel remains important, although plastics and sophisticated composite materials are increasingly dominant.

-- Key innovation --

Iron-making was perhaps not as revolutionary as some earlier transitions between lithic modes or the first use of metals, but the development of the high-temperature furnace was a breakthrough.

-- Sophistication estimate --

FactorDiscussionTime resources (seconds)
InputsA knowledge of geology is required: 4 hours. To obtain the ore (more widely available than copper ore): 4 hours. Also required are a crucible and high temperature furnace, along with charcoal fuel: two 8-hour days. Tools are needed to mine the ore and construct the furnace, for which assume a bronze package: 350,000 person-secs. 436400
Skill acquisitionThe necessary skills include producing the high temperatures for melting iron, handling the molten metal, and understanding how carbon or other ingredients affect the metal's properties: 20 hours.72,000
PreparationThe iron has to be smelted from its ore: 12 hours.43,200
ManufactureThe work involves creating a mould, melting the iron, and polishing the cast object into a finished product: 2 days. Finally, it has to be mounted: 4 hours.72,000
TOTAL≈ 625,000


The following table summarises the technological sophistication of different types of cutting tools and the times at which they first appeared.

Technology          Sophistication          Appearance     
Mode 11000Pre-G 1
Mode 27000Pre-G 1
Mode 335,000Pre-G 1
Mode 490,000G 1
Mode 5150,000G 500
Neolithic180,000G 1600
Copper290,000G 1760
Bronze380,000G 1860
Iron625,000G 1920

This chart shows growth of technological sophistication over time, based on the above table:

While these figures for technological sophistication are rough and ready, it is not surprising to see the kind of accelerating growth shown in the chart.

To make the numbers easier to write, it will be helpful to introduce some abbreviations. Thus, 90,000 person-seconds = 90x103 ps = 90 kps, where ps is short for person-seconds and kps is short for kilo-person-seconds, i.e. 1000 person-seconds; similarly we can have Mps (mega=106), Gps (giga=109) and Tps (tera=1012).

To conclude, I want to make two final points:
  • Only modern humans have used tools with sophistication 90 kps and above (Mode 4 lithics and higher). However, this does not mean modern humans only use tools above 90 kps. Humans continued to use Modes 1-3 lithics alongside more sophisticated tools, while some groups, like Australian aborigines, did not use anything higher than Mode 3. On aborigine tool-making, see R. Foley and M.M. Lahr, 'Mode 3 Technologies and the Evolution of Modern Humans', Cambridge Archaeological Journal, 1997, 7(1): 3-36; A. Brumm and M.W. Moore, 'Symbolic Revolutions and the Australian Archaeological Record', Cambridge Archaeological Journal, 2005, 15(2): 157-175.
  • The adoption of a more sophisticated technology does not mean the abandonment of less sophisticated ones. At most, less sophisticated technologies become rarer over time, as more sophisticated ones are taken up. However, a relatively simple technology, such as a hammer, can be well adapted to its purpose and remain in widespread use despite massive growth of technological sophistication in other areas. Thus lower mode lithics continued alongside higher ones, neolithic tools continued alongside bronze, and bronze continued alongside iron. In principle, an astronaut landing on the moon could still pick up a pebble to fashion a Mode 1 tool for a purpose like prising open an equipment canister.