After harnessing fire, humans discovered other forms of energy. The earliest known use of wind power is the sailing ship; the earliest record of a ship under sail is that of a Nile boat dating to around 7,000 BCE.[43] From prehistoric times, Egyptians likely used the power of the annual flooding of the Nile to irrigate their lands, gradually learning to regulate much of it through purposely built irrigation channels and "catch" basins.[44] The ancient Sumerians in Mesopotamia used a complex system of canals and levees to divert water from the Tigris and Euphrates rivers for irrigation.[45] Archaeologists estimate that the wheel was invented independently and concurrently in Mesopotamia (in present-day Iraq), the Northern Caucasus (Maykop culture), and Central Europe.[46] Time estimates range from 5,500 to 3,000 BCE with most experts putting it closer to 4,000 BCE.[47] The oldest artifacts with drawings depicting wheeled carts date from about 3,500 BCE.[48] More recently, the oldest-known wooden wheel in the world as of 2024 was found in the Ljubljana Marsh of Slovenia; Austrian experts have established that the wheel is between 5,100 and 5,350 years old.[49] The invention of the wheel revolutionized trade and war. It did not take long to discover that wheeled wagons could be used to carry heavy loads. The ancient Sumerians used a potter's wheel and may have invented it.[50] A stone pottery wheel found in the city-state of Ur dates to around 3,429 BCE,[51] and even older fragments of wheel-thrown pottery have been found in the same area.[51] Fast (rotary) potters' wheels enabled early mass production of pottery, but it was the use of the wheel as a transformer of energy (through water wheels, windmills, and even treadmills) that revolutionized the application of nonhuman power sources. The first two-wheeled carts were derived from travois[52] and were first used in Mesopotamia and Iran in around 3,000 BCE.[52] The oldest known constructed roadways are the stone-paved streets of the city-state of Ur, dating to c. 4,000 BCE,[53] and timber roads leading through the swamps of Glastonbury, England, dating to around the same period.[53] The first long-distance road, which came into use around 3,500 BCE,[53] spanned 2,400 km from the Persian Gulf to the Mediterranean Sea,[53] but was not paved and was only partially maintained.[53] In around 2,000 BCE, the Minoans on the Greek island of Crete built a 50 km road leading from the palace of Gortyn on the south side of the island, through the mountains, to the palace of Knossos on the north side of the island.[53] Unlike the earlier road, the Minoan road was completely paved.[53]Photograph of the Pont du Gard in France, one of the most famous ancient Roman aqueducts[54] Ancient Minoan private homes had running water.[55] A bathtub virtually identical to modern ones was unearthed at the Palace of Knossos.[55][56] Several Minoan private homes also had toilets, which could be flushed by pouring water down the drain.[55] The ancient Romans had many public flush toilets,[56] which emptied into an extensive sewage system.[56] The primary sewer in Rome was the Cloaca Maxima;[56] construction began on it in the sixth century BCE and it is still in use today.[56] The ancient Romans also had a complex system of aqueducts,[54] which were used to transport water across long distances.[54] The first Roman aqueduct was built in 312 BCE.[54] The eleventh and final ancient Roman aqueduct was built in 226 CE.[54] Put together, the Roman aqueducts extended over 450 km,[54] but less than 70 km of this was above ground and supported by arches.[54]
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