A Brief History of Motion Read online

  People living in the Carpathian region would have had both the means and the motivation to create wheeled vehicles during this period, which is known as the Copper Age. As the name suggests, this was when metalworking first began, allowing tools to be made from copper rather than stone. (Bronze, an alloy of copper and tin, was subsequently found to be stronger than copper alone, ushering in the Bronze Age.) The Carpathian Mountains are rich in copper ore, but producing an ingot of the metal still required the processing of large amounts of ore, which had to be dug out of the mountains by hand. Shifting heavy loads of ore would have been laborious, even with the aid of wicker backpacks, or large baskets dragged on sledges or on top of wooden rollers.

  The earliest wheels, such as the Ljubljana Marshes Wheel (dated to around 3200 B.C.E.) were made of planks fastened together using battens.

  So an enterprising copper miner might first have had the idea of attaching four wooden wheels to the base of a wicker basket, to make what is now known as a mine cart, which could then be pushed or pulled by hand. Cutting up wood to make wheels and axles would have been quite possible using copper woodworking tools such as chisels and adzes—items that copper miners would have had access to. Contrary to popular belief, the earliest wooden wheels would not have been made by cutting circular slices from large logs; that would have required metal saws, which are a later invention, and single-piece wheels made by slicing logs are small (making them less able to traverse uneven ground) and weak. Instead, logs were repeatedly split from end to end using hammers and wedges, and wheels were cut from the resulting planks. By fixing two or more planks together, wheels with a larger diameter than that of the tree from which the planks were cut could be made. (The Ljubljana Marshes Wheel, for example, is made from two planks fastened together using wooden strips, called battens.)

  A representation of a four-wheeled vehicle is scratched onto this pot, found in Bronocice in southern Poland and dated to around 3500 B.C.E.

  The idea that the first wheeled vehicles were hand-pulled Carpathian mine carts, proposed by the historian Richard Bulliet in 2016, would explain why so much of the early evidence for wheels is found in and around the region. More than 150 clay drinking vessels with four wheels, dating from 3500–3000 B.C.E., have been found on the southern flanks of the Carpathian Mountains. They have been discovered in settlements and graves, which suggests that they were not mere toys, but were models of larger vehicles that played an important role in the local culture. Many of them have patterns on their sides that are suggestive of wickerwork. But even if these were indeed the first wheeled vehicles, the idea almost immediately led to the creation of four-wheeled wooden wagons pulled by cattle. The wagon drawn on the Bronocice pot shows the pole and yoke that would have allowed it to be pulled by two oxen. These were the first vehicles capable of carrying heavy loads, or people. Whether the first wheels and wagons originated in Europe, in Mesopotamia, or in the area in between—the Pontic steppe around the north of the Black Sea—the notion of the four-wheeled wagon quickly spread along the trade routes that connected them. By 3000 B.C.E. such wagons could be found in all three regions, though they were being put to rather different uses.

  REINVENTING THE WHEEL

  In Europe wagons seem to have been used primarily for agriculture. It seems unlikely that they were used to transport loads over long distances—something that requires relatively flat, open country or well-maintained trackways. Early wagons lacked steering, which made them difficult to maneuver, and they also required care and maintenance. Repairing a broken wheel or axle would have required woodworking tools and would have been difficult to do while out and about. So early wagons would probably have had quite a limited operating range. In Europe, their use may have been restricted to short local trips within a particular farm or community, for example to transport manure into the fields and carry harvests and firewood into villages.

  On the plains around the north and east of the Black Sea, however, the herders of the Pontic steppe found quite a different use for these vehicles: as mobile homes. Using wagons to carry food, supplies, and other possessions allowed nomads to move deep into the open steppe with their herds of cattle and sheep. These wagons moved slowly, at walking pace, and may not have covered much distance each day, as the herd moved from one source of fodder to the next. Their cultural significance is apparent from the appearance of “wagon graves,” which have a wheel buried in each corner, so that the grave itself forms a kind of wagon, carrying its occupant into the afterlife. Such graves first appear on the Black Sea plains around 3300 B.C.E. The distinctive tradition of wagon nomadism in this region persisted for thousands of years; it is mentioned by the Greek historian Herodotus in the fifth century B.C.E., was adopted by the Mongols in the thirteenth century C.E., and survived into the modern era.

  Map showing where the earliest known wheels (and depictions of wheels) have been found, from Europe to Mesopotamia.

  In Mesopotamia, meanwhile, the four-wheeled wagon was adopted for military and ceremonial use. The Royal Standard of Ur, a Mesopotamian artifact dated to around 2600 B.C.E., depicts four-wheeled battle vehicles being pulled by onagers (similar to donkeys) as part of a ritual procession. Four of the wagons carry a driver, a warrior, and a supply of javelins, which suggests they were used as mobile battle platforms. Enemy combatants are shown being crushed under their wheels. Yet these wagons may not have proved terribly useful in combat: they offered little protection to the driver or warrior, would not been have able to move quickly, and, lacking steering, would not have been very maneuverable. Their main uses may have been to transport the king and his generals to the battlefield (the king is depicted with his own battle wagon, without any javelins), to provide observation posts, and to intimidate the enemy. They may also have formed part of victory and funeral parades. As the historian Stefan Burmeister puts it, wheeled vehicles “brilliantly combined locomotion with social elevation,” raising Mesopotamian rulers above their subjects and granting them the superpower of being able to move while standing still.

  Depiction of wheeled vehicles in Mesopotamia, from the Royal Standard of Ur, dated to around 2600 B.C.E.

  Wheeled vehicles were sufficiently unusual in this period in that they had little or no impact on the layout of settlements or early cities. Some of the earliest human settlements even seem to have lacked streets between the buildings; instead, houses were constructed right next to each other, and people moved between them by walking across their roofs, with hatches providing access to the buildings below. Mesopotamian cities had thoroughfares between their main gates and, in some cases, ceremonial avenues, which would have been large enough to allow the use of wheeled vehicles in parades. Their irregular mazes of narrow streets provided protection against sun and windblown dust; wide, straight streets suitable for vehicles were unnecessary because goods were transported by porters or pack animals. In Europe and Mesopotamia, the layout of settlements—what we now call urban planning—was entirely driven by the needs of people, not vehicles. For the nomads who lived in their wagons, by contrast, their built environment was not merely influenced by their vehicles—it consisted of them.

  Wagons were clearly used in very different ways in these three regions. The wheels depicted on the Royal Standard of Ur even look different from European and Black Sea examples: they are made of three wooden pieces that fit together, but the pieces are curved rather than straight planks. This suggests that it was the idea of the wheel, rather than the specific knowledge of how to make it, that spread from its original birthplace. Once you’ve seen a wheel, after all, you can describe it to someone else or try to make your own—something that is not possible with, say, novel metallurgical or agricultural techniques based on specialist knowledge. Even so, wheels were only adopted in situations where the time and effort needed to make them could be justified. And that explains the surprising fact that, for thousands of years after their invention, wheels were not widely used.

  THE RISE AND FALL OF THE CHAR
IOT

  The Egyptians, for example, built the pyramids during the third millennium B.C.E. without the use of any wheels at all. They were surely familiar with the concept—their trade with neighboring Mesopotamia encompassed both goods (such as gold) and ideas (such as writing)—but when it came to the wheel, Egyptians were unimpressed. For moving things around, wheeled vehicles were not really needed; why bother with them when you have the Nile, the lifeline running through Egyptian civilization? In Egypt, as in Mesopotamia, heavy loads were most easily transported on water, using barges or rafts. On land, the Egyptians employed levers and rollers to move the large stone blocks used in construction. In any case no wheeled vehicle in existence could have borne their weight. Other cultures also chose to ignore the wheel. One common explanation for this is that wheeled vehicles require the availability of draft animals. But the Egyptians had oxen to pull their plows, yet still chose to ignore wheels, as did the cattle-herding societies of sub-Saharan Africa. And in the Americas, where wheels are found on small animal figurines, people could easily have built hand-drawn mine carts. But evidently they concluded that wheeled vehicles were not worth the bother.

  Wagons with four solid wheels were heavy and slow and, lacking steering, could only make gentle turns, which limited their usefulness. Two-wheeled vehicles, or carts, which had emerged by 3000 B.C.E., were more maneuverable and could make much tighter turns, particularly if the wheels could turn independently, rather than being fixed at the ends of a single axle. Starting in around 2000 B.C.E., these two-wheelers began to evolve into a new and much faster vehicle: the chariot. Like a cart, it had two wheels, with the load balanced over a single axle. But chariots had spoked rather than solid wheels. These wheels could be much larger and lighter, which reduced rolling resistance and allowed chariots to achieve unprecedented speeds. Higher speeds were also possible because chariots were pulled not by oxen but by horses, which had been domesticated in the northern steppes starting around 3500 B.C.E. Two or four trotting horses could pull a chariot at 8 mph, more than twice the speed of an ox-drawn cart or wagon; galloping horses could pull a chariot faster still, at least on flat and relatively open ground.

  Making a spoked wheel is far more complicated than making a solid one because it must be assembled from dozens of carefully shaped parts that have to fit together precisely. Making spoked wheels was the work of dedicated wheelwrights using specialist tools. The appeal of spoked wheels is not simply that they are lighter and allow vehicles to move faster. The maximum size of a solid, three-plank wheel is limited by the size of the planks available, which in turn is limited by the diameter of the largest available trees. Large spoked wheels, however, could be constructed even when large trees were not available, as was the case on the Black Sea plain, where they seem to have first emerged. The use of spoked wheels, in some cases as large as two meters in diameter, also allowed chariots to be driven at speed even over somewhat uneven terrain. Once the idea of the horse-drawn, two-wheeled chariot had emerged, it spread quickly, initially throughout the Middle East, and ultimately as far west as the British Isles and as far east as China. And no wonder, because chariots proved to be a transformational technology on the battlefield.

  The pioneers of fast, lightweight military chariots were the Hittites, who used them to conquer most of Anatolia (modern-day Turkey) by 1700 B.C.E. This prompted neighboring peoples to adopt war chariots, including the Egyptians, who began using wheels for the first time. Capable of reaching the unprecedented and awesome speed of 25 mph, such chariots became closely associated with kingly prestige and military prowess. They were typically drawn by two horses and were used as mobile battle platforms that carried two or three people: a driver, an archer, and, in some cases, a shield bearer. The Egyptians further refined the chariot by paring down the design to make it even lighter and faster: one chariot found in the tomb of Tutankhamen weighed a mere thirty-five kilograms. (A wagon with four solid wheels, by contrast, might have weighed six hundred to seven hundred kilograms, and a cart with two solid wheels about half that.)

  During battles, chariots would either face off directly in opposing rows (with archers firing at enemy chariots) or support infantry by harrying enemy troops with volleys of arrows. Chariots also carried spears, which could be thrown at closer range. The Battle of Kadesh, in 1274 B.C.E., is thought to have been the largest chariot battle in history, involving around five thousand chariots and more than fifty thousand soldiers. It pitted the Egyptians under the young king Rameses II, five years into his reign, against the Hittite king Muwatalli II. The Hittites lured the Egyptians into an ambush and scattered them with a surprise chariot attack. As his men began to retreat, Rameses leaped into his chariot and launched a counterattack. Leading several charges using the Egyptians’ light, nimble chariots, Rameses inflicted heavy losses on the Hittite forces and their slower, heavier vehicles. The surviving Hittites ended up pinned against a river, where they abandoned their chariots and swam for their lives.

  The battle is generally deemed by historians to have been a draw: the Egyptian forces ultimately failed to capture the city of Kadesh and returned home. But that did not stop Rameses from depicting himself as a heroic warrior, single-handedly turning the tide of the battle in his chariot, in a series of reliefs that were carved in temples across Egypt. These are perhaps the most famous examples of an entire genre of images from the era of chariot warfare, depicting warrior kings as they smite their enemies, parade in triumph, or hunt wild beasts in their vehicles. Rulers were buried with chariots as symbols of their military might; a total of six were found in Tutankhamen’s tomb. Each would have taken about six hundred man-hours to build, according to a modern estimate. Access to these expensive, high-tech weapons signaled membership in the social and military elite. The Hittites and other peoples also depicted their gods riding in chariots, which implied that chariot-riding kings were their earthly representatives.

  Pharaoh Rameses II looking heroic in his chariot at the Battle of Kadesh, as depicted in a relief on the walls of the Ramesseum in Thebes, Egypt.

  But the supremacy of the chariot on the battlefield did not last. Chariots could not be reliably used on uneven terrain, so their advantages were easily neutralized by placing obstacles across the battlefield to hinder their passage, or simply by avoiding battle on flat plains. Progress in horse breeding gradually produced larger, stronger animals that were capable of carrying a soldier in full armor. Cavalry units could move just as quickly as chariots, but were even more agile and could traverse uneven ground. That chariots were obsolete was vividly demonstrated at the Battle of Gaugamela in 331 B.C.E. The Persian king Darius III fielded chariots with scythes attached to their wheels and even had the battlefield cleared of bushes and vegetation that might impede their movement. But the Greek forces, led by Alexander the Great, opened their ranks to let the charging chariots pass, then surrounded and destroyed them. A mosaic found at the Roman town of Pompeii, based on an earlier Greek painting, depicts Alexander triumphant on his horse as a defeated Darius flees the battlefield in his chariot.

  By the first century B.C.E, when Julius Caesar led the first Roman expedition to Britain, he was surprised to find that the British tribes were still using war chariots, which had fallen out of use in continental Europe. (Caesar noted that British warriors used the chariots to carry them into battle, where they would fight on foot while their chariots waited nearby, ready to pick them up if needed. They were, in effect, getaway vehicles.) Even as chariots began disappearing from the battlefield, however, they retained their association with kingly power and divine status. The gods were still assumed to ride chariots—the Greek sun god Helios was said to drive one across the sky every day, for example—and they were ridden in ceremonial processions by triumphant Roman generals, who would not have been seen dead in a chariot during an actual battle. Chariot racing was also an important part of the Olympic Games and a popular sport in Roman culture. With its thrilling speed and the potential for spectacular accidents, c
hariot racing was probably the world’s first mass-spectator sport. Gaius Appuleius Diocles, a charioteer of the second century C.E., was both a celebrity and one of the best-paid athletes in history: his winnings are said to have exceeded 35 million sesterces, equivalent to more than $100 million today, ranking him among the Roman world’s wealthiest men.

  THE RULES OF THE ROMAN ROAD

  The Romans may have shunned chariots on the battlefield, but they used less glamorous two-wheeled carts and four-wheeled wagons to carry military equipment and supplies, and to haul agricultural produce and other goods in and out of cities, taking advantage of the extensive and well-maintained Roman road network. Paving of roads began with the construction of the Via Appia, a military highway running southeast from Rome, starting in 312 B.C.E., and soon became widespread, both within towns and outside them. Laws governing the minimum width of Roman roads and streets date back to the fifth century B.C.E. And some of the first formal rules governing the use of wheeled vehicles, and the earliest examples of urban environments being reshaped to accommodate them, also date to the Roman period.

  The use of vehicles within the city of Rome seems to have been entirely forbidden for centuries after its founding. Its streets were evidently too narrow and crowded for vehicular traffic; goods were instead moved through the city streets using mules or human porters. To facilitate deliveries and construction, Julius Caesar introduced a law in 45 B.C.E., the Lex Julia Municipalis, allowing the use of wheeled vehicles in the city, but only from dusk until dawn, when the streets were the least busy. This rule had the obvious merit that anyone breaking it would have to do so in broad daylight and would be clearly visible. The only exceptions were for vehicles carrying certain priests and priestesses, and materials required for the construction or maintenance of temples. Juvenal, a Roman poet, grumbled about the noise made by vehicles at night, which suggests that the Lex Julia was still in force in the early second century C.E.