Legacy of the Ancient World

Steven Dutch, Natural and Applied Sciences, University of Wisconsin - Green Bay
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Pre-Greek Accomplishments

The key to technology and civilization is enough food to eat. Roughly 8,000 years ago, agriculture, irrigation, and animal domestication had appeared in the Middle East and were independently discovered in many other times and places. Ceramics (pottery) likewise appeared in many places. The discovery of metals was not so widespread, although smelting seems to have been independently discovered in the Middle East, China, and southeast Asia. Seven metals are mentioned in the Bible: gold, silver, copper, iron, lead, mercury (quicksilver) and tin. The chemical symbols for these elements (Au, Ag, Cu, Fe, Pb, Hg, and Sn, respectively) are unrelated to their modern names. The symbols come from their Latin names, a testament to their antiquity. Probably the first metals discovered were gold and silver, and perhaps copper. These metals occur in nature in the metallic form, although copper does so rarely. These metals can be beaten into shape without smelting; the Copper Culture Indians of the American Midwest used metallic copper from Michigan in just that way about 4000 B.C. But sophisticated metal use requires smelting: removal of metal from its ores.

How did Metallurgy Begin?

There are many riddles connected with ancient metallurgy, starting with how smelting was discovered at all. The campfire theory holds that ores were accidentally used to build stone enclosures around cooking fires, and that people noticed new metals appearing from the ashes. This process may have worked for lead and mercury, which are easily smelted from their ores at low temperatures. However, temperatures are not high enough in campfires to smelt copper, and certainly not iron. Another possibility is that people experimenting with mineral pigments discovered accidentally that they contained metals. This theory is attractive because iron and copper minerals are also brightly-colored natural pigments and it furnishes a likely setting for people to tinker with various methods and observe the results. But the most likely setting to discover smelting is one where high temperatures are routinely applied, preferably under oxygen poor conditions, where ore minerals were likely to be placed, and where the process would be repeated often enough for people to observe cause and effect clearly. Such a place was known in ancient times: pottery kilns. Mineral pigments used in coloring and glazing pottery would occasionally have been chemically reduced to pure metal (and often are in primitive kilns today). Ancient smelting was laborious at best: to keep the fire hot enough, assistants (most likely slaves) would have to pump bellows for long periods. Even then, the final result was likely to be a mass of metal mixed with slag that would have to be crushed and the metal picked out by hand.

The Mystery of Bronze

Copper was the first metal to be smelted and used in abundance, but the real metallurgical innovation was the discovery of copper alloys. Brass is an alloy of copper and zinc. Even though zinc was not known as a metal in ancient times, zinc and copper minerals often occur together. Zinc could be a contaminant in copper ores often enough for the discovery of brass to be reasonably simple. Not so for bronze, an alloy of copper and tin. Copper and tin minerals rarely occur together and there is no abundant source of tin in the Middle East. The nearest source known is in Afghanistan, a plausible place because a precious blue stone, lapis lazuli, comes from the same region and was widely traded in ancient times. Nevertheless, it is a deep mystery how bronze came to be discovered. But it was the first industrial metal; much harder than copper and able to maintain a sharp edge. The fact that the earliest metalworking period is called the Bronze Age is testimony to the importance of bronze.

Iron

Iron requires a much higher temperature to smelt than copper and seems to have been discovered by the Hittites of present-day central Turkey. The myth is that the Hittites overwhelmed their neighbors because of their superior iron weapons. The reality is that ancient iron was far too variable in quality to be clearly superior to bronze. Pure iron is very soft; most ancient iron was impure and often brittle. The real reason iron swept the world is that it was cheap; far more abundant than copper and tin. A thousand peasants armed with cheap iron swords can overwhelm a hundred trained soldiers with fine bronze swords. Through most of history iron was extracted by smelting ore to get "bloom", a mixture of iron and slag; the iron was broken free and laboriously pounded into larger masses. To shape it, the iron was heated red hot and pounded into shape. Melting iron and pouring it into molds, as we do, would have been the wildest fantasy to ancient metalsmiths; they would regard our cheap iron and steel as the most fabulous luxury. Streets paved in solid gold would be scarcely more amazing to someone from ancient times than railroads with iron rails.

Masonry

The ancient world worked materials other than metals. With bronze and later iron tools, stone cutting, dressing, and sculpting were possible. In many places (for example, by the Incas of South America) these operations were done to high sophistication even with stone tools. To build large structures, it is necessary to have some means of spanning openings: an arch. Post- and-lintel arches, uprights with a beam across the top, are intuitively obvious. Stonehenge is a famous prehistoric example in stone. Larger openings can be spanned by stepping stones out over each other in an inverted-staircase arrangement until the stones meet. This is called a corbelled arch; it was widely used in the Old World and the Americas. The circular arch, a fan of tapered stones where increased weight acts to press the stones tighter, was known only in the Old World (except for one intriguing exception: the Inuit igloo). Large rooms were spanned with large timbers and later with masonry domes or arches, but the truss, the use of a triangle of timbers to create rigidity, was unknown until the Middle Ages.

Simple Machines

Muscle power is augmented by machines, and the three fundamental simple machines were known in ancient times. The lever consists of three elements: the place where force is applied, the load to be moved, and the pivot point or fulcrum. These can be arranged in various orders. The familiar situation of pushing down on a beam to lift a load has the elements in the order force- fulcrum-load. A wheelbarrow is a lever with its elements in the order force-load-fulcrum (the wheel is the fulcrum). The lever was still amazing enough that in the third century B.C., the Greek scientist Archimedes could awe listeners by saying "give me a place to stand and a lever long enough, and I will move the Earth". The second simple machine is the wedge. The general idea behind a wedge is that a small force applied over a long distance along the length of the wedge translates into a large force acting over a short distance at right angles to the wedge. A hammer blow drives a wedge easily into a crack, while the wedge pries the crack apart with enormous force. A variation on the wedge principle is the inclined plane; it's a lot easier to push a load up a gentle slope than lift it vertically.

The third and most profound simple machine is the wheel. The wheel is a good exercise in understanding why technology develops. For starters, why is the wheel virtually unknown in biology? The answer is that wheels do not work well on uneven surfaces. This insight helps us understand why some societies never developed the wheel. The Incas had superb roads, but many of these roads consist of steep flights of steps hacked into mountains and rope bridges crossing gorges. Amazing as this engineering is, wheels would not be very effective on Inca roads. To invent the wheel in a roadless world, the necessary prerequisites seem to be: large expanses of flat open land, a large amount of goods to move, and a need to move regularly. Mountains and jungle do not favor the development of the wheel. Nomads with minimal possessions can carry everything on pack animals. Sedentary farmers may have a lot to move, but not over long distances; pack animals will suffice for them as well. The wheel seems to have been invented not in the agrarian lands of the Middle East, but in the steppes to the north, where the land is flat and the civilized nomadic peoples had a more complex lifestyle and numerous possessions to move.

There are numerous simple compounds of the three simple machines. Wrap an inclined plane around a cylinder and you get a screw. The screw was known in ancient times and used in two settings: to convert rotary motion into linear motion along the screw, and in conjunction with the lever, to apply force. Threaded fasteners were rare until the late 19th century; to make a screw in ancient times, you cut the threads manually with a file. Nuts were made by drilling a hole in a metal block and forcing the nut onto the bolt using a primitive wrench, yet another kind of lever (this is an inefficient version of the modern process of cutting threads with a tap). Once made, nuts and bolts were commonly joined by a cord until use because every single one was unique. We can also combine the wheel and lever in several ways, using the axle of the wheel as the fulcrum. One such compound is the crank, which was curiously unknown in the West in ancient times, although it was known in China. The pulley uses the radius of a wheel as the lever; the real power of the pulley is that several pulleys can be connected to allow huge loads to be lifted with small forces.

A modern carpenter would recognize many basic hand tools in even the most ancient tool kits. Hammers, saws, squares, plumb lines, pliers, chisels and files were all in use. Ancient shovels, hoes, rakes and pitchforks looked pretty much like their modern equivalents. Conspicuously missing, of course, were tools for working with threaded fasteners, like screwdrivers and wrenches.

Heavy engineering in ancient times, apart from large buildings, included the construction of catapults and other kinds of seige machinery, and shipbuilding. By 3000 B.C. boats capable of crossing the open Mediterranean were in use.

Glass

Glass-making was known to the ancient Egyptians. Glass results from heating quartz sand with lye or potash, and can be regarded as the first truly synthetic material. Glass was initially placed on a par with gem stones, but as the technology spread, the price plummeted. The Greeks made lovely small bottles by winding threads of molten colored glass onto a core of clay mixed with manure, then scoring the still-soft glass with a knife to smear the colors, much the way one might with cake frosting. There is a truly amazing video of the technique on view at the Corning Glass Museum in Corning, New York. By Roman times, clear glass was available in sufficient quantity and cheaply enough that even common people could afford it. At about the same time, glass- blowing was also invented, further driving down the cost of glass vessels.

A famous ancient quotation tells us a lot about ancient glass technology. Nowadays we would say something is clear as glass, or that a still lake looked like a mirror. It was a lot different 2000 years ago. Writing about our spirtual ignorance, Saint Paul that now we see "through a glass darkly". In other translations, the quotation is translated "now we see indistinctly, as in a mirror". Either way, the quote is revealing; ancient glass was clear enough to transmit light but not to see through sharply. Ancient mirrors were polished metal with uneven surfaces and imperfect finish.

One of the first areas of "pure science", as well as one of the first cases of pure science being applied, was astronomy. The Egyptians and many other peoples had accurate calendars.

Greek Technology and Science

Among the Greeks, we can distinguish several major traditions:

The Ionian tradition, mercantile and experimental, grew up on the islands of the Aegean. This was the closest approach in ancient times to what we would call a technical and scientific society. Ionian colonists settled islands west of Greece, accounting for the confusing fact that the "Ionian Sea" on present maps is on the opposite side of Greece from where the Ionian culture originated. Important Ionians include Aristarchus of Samos, the first known thinker to reason that the Earth goes around the Sun, and Democritus, the first scientist to describe atoms.

The Pythagorean tradition was mathematical but mystical. Pythagoreans were fascinated by the so-called perfect solids, whose faces were regular polygons, and also by whole numbers. They were so shocked to discover that the square root of two could not be expressed as a ratio of whole numbers that according to legend, they decreed death for any member of the cult who divulged the secret to outsiders. To this day, "irrational" has a sinister non-mathematical meaning, although it originally meant only that a number could not be expressed as a fraction.

The many Athenian schools of philosophy, stressing logic, deduction, and idealization are epitomized by Plato, Aristotle, and Socrates. Plato, a Pythagorean, stressed the existence of an "ideal" world of which our sense picture is only an imperfect approximation. Aristotle is best known for his emphasis on the use of pure reason in understanding the world. Athens enjoyed a famous and glorious, but brief "Golden Age" under the leadership of Pericles about 450 B.C.

Hellenistic Tradition

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Socrates taught Plato. Plato taught Aristotle. Aristotle taught Alexander the Great. Something apparently got lost in translation. Alexander, from Macedonia in northern Greece, conquered all of Greece, then turned the tables on the Persian Empire, which had invaded Greece several times. He overran Persia, and by his death in 323 B.C. had carved out an empire (map above) that reached from Greece to India and Egypt to central Asia. The empire fragmented after Alexander's death, but a transplanted Greek culture, termed Hellenistic, took root around the eastern Mediterranean. (Most of the rest of the empire soon reverted to its old ways. Interestingly enough, some of the longest surviving Greek successor kingdoms were in remote central Asia.) It is thanks to this transplanted Greek culture that the New Testament was written in Greek. The great Library at Alexandria was once the greatest repository of learning in the ancient world. Hellenistic Greek colonists settled in Sicily, southern Italy, and even around the Black Sea in modern Russia. Important Hellenstic scientists included Euclid, who codified geometry, Eratosthenes, who calculated the size of the Earth, and Ptolemy, whose model of the solar system would dominate European thinking for 1500 years. Heron of Alexandria was one of the first known people to experiment with steam power. Among the colonists, the most famous was the inventor Archimedes, who lived at Syracuse in Sicily.

The major Greek traditions represent ways of thinking that have been independently discovered many times. All are appropriate in certain situations; it is wrong to stereotype any as "helpful" or "harmful" to science and technology. The pragmatic approach of the Ionians speaks to us most clearly today, but scientists constantly speak of ideal concepts: for example, objects would fall at the same rate if not for air resistance. Plato would agree. Scientists have a faith in whole numbers that Pythagoras would find familiar. Early experiments to determine chemical formulas almost never gave exact whole numbers for the proportions of atoms, just very close. But the numbers were so close that scientists were convinced they reflect the existence of discrete, countable atoms. Finally, it is impossible to overstate the importance of logic and deduction in science. It is hardly Aristotle's fault that people later put him on a pedestal.

Why didn't the Greeks develop modern science?

First and foremost, they weren't trying to be us! They were more interested in fundamental questions like the nature of cause and effect. When they observed a rock being thrown, they weren't interested in its exact path, but the question why does it keep moving without anything pushing it?. They didn't have our agenda and they weren't interested in the questions that intrigue us. Also, it was not at all clear that close investigation of nature would reveal anything of use or interest. We have inherited the results of work by thousands of people over centuries, but would you invest your life in studying nature in a world where very little was known about science? Those that did tended to focus on small problems with foreseeable solutions. It's one thing to spend your life carrying bricks to build a cathedral; it's another matter to spend your life making and accumulating bricks on the off chance that somebody might someday build a great building with them. We can sum up the riddle of the Greeks by noting that they had all the elements of modern science: observation, experiment, mathematics, deduction. But nobody ever achieved a synthesis of all these elements.

The Etruscans

The Etruscans spoke a non-Indo-European language and occupied the northern half of Italy in Pre-Roman times. Because their language is extinct and unrelated to European languages, there was once little hope of deciphering their history. Thanks to modern techniques of linguistic analysis, much of their language can now be read. The Etruscans were a fairly sophisticated people, with expertise in iron working and extensive trade contacts. Their principal historical importance is as a link between the Greeks and the Romans. The Etruscans used the Greek alphabet to write their own language, and passed it on to the Romans, along with many other Greek ideas. A couple of tidbits from the Etruscans: the letter F and the "Roman" numerals V, L and D. The early Greeks had a letter like F called "digamma" - it looked like two letter gammas joined together and represented a "kh" sound. The letter fell into disuse among the Greeks because they had another letter with nearly the same sound, so the Etruscans adopted it for the "f" sound, which the Greeks did not have (the "ph" of the letter phi was pronounced "p-h", not "f"). For several centuries Rome was ruled by the Etruscans, but the Romans overthrew the Etruscans and eventually absorbed them. Etruscan was apparently widely spoken for a long time, but nobody in Rome bothered to leave an account of the language. The map below shows some of the principal peoples of western Europe about 300 B.C.

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Created 13 January 1998, Last Update 21 September 1999

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