When the last ice age ended nearly 12,000 years ago, the climate warmed, the seas rose and rains fell on the grassy steppes of the ancient Near East. It was here, archaeologists believe, in a semicircular region now known as the Fertile Crescent, that agriculture may have first taken hold, some of the world's first great cities were built, and humans developed some of the first clear hallmarks of "civilization," including writing, mathematics and religion.
The term "Fertile Crescent" was coined in 1914 by the American Egyptologist James Henry Breasted in his popular high-school textbook "Outlines in Human History." He used it to describe a roughly crescent-shaped region encompassing modern-day Iraq, Syria, Lebanon, Jordan, Israel, Egypt, and parts of Turkey and Iran.
"The earliest home of men in this great arena of western Asia is a borderland between desert and mountain — a kind of cultivable fringe of the desert — a fertile crescent having the mountains on one side and the desert on the other," wrote Breasted. "This great semicircle, for lack of a name, may be called the fertile crescent."
More than 10,000 years ago, the nomadic peoples of this region harvested the wild grasses that grew in the rain-fed foothills and gathered together in small village settlements. Over millennia, they began to domesticate wheat and barley (beer was one of their first and best ideas), and to breed wild game into domesticated goats and sheep for meat, dairy and wool.
The agricultural revolution began in earnest when farmers learned how to irrigate the fertile soils of the river valleys, where mineral-rich layers of silt enabled larger and more consistent harvests, which supported larger and more permanent human settlements.
Welcome to Uruk, the First Great City
There were very large settlements and even some proto-cities in Mesopotamia as early as 5000 B.C.E., but nothing compares to the grandeur and cultural importance of Uruk, a massive walled city in Sumer (southern Mesopotamia) that reached its height from 4100 to 3100 B.C.E.
"Uruk was huge, it was fortified, it had monumental buildings — it really eclipsed anything else in the region," says Amanda Podany, author of "The Ancient Near East: A Very Short Introduction" and a history professor at California State Polytechnic University. "I'm always hesitant about saying 'the first' of anything, but Uruk really does seem to be a remarkably large and highly innovative city for the time that it was founded."
The agricultural abundance of the region meant that people had the resources and the time to build some of the world's first monumental architecture, including huge temples on terraces. They also constructed storehouses for surplus grain and fortified walls around their cities.
"You don't build walls unless people are threatening you," says Daniel Snell, an expert on the ancient Near East who taught history at the University of Oklahoma. Podany wonders if one of the reasons Uruk grew so large was that people gathered there seeking refuge during a warring period.
At its height, archaeologists estimate that between 25,000 and 40,000 people lived inside Uruk's massive mud-brick walls. While many were farmers, there were also weavers, artists, priests, scribes, construction workers and brewers. Podany says that the Uruk period signaled the beginning of an urban revolution that reshaped human society worldwide.
"It was a slow revolution, but in terms of human history, it's revolutionary," says Podany, "because once people started living in cities, they never stopped."
Writing Began as Recordkeeping
Perhaps the greatest cultural innovation to come out of the 1,000-year Uruk period was writing. Some of the earliest cuneiform tablets have been recovered from Uruk, where historians believe that ancient scribes used the wedge-shaped script to keep track of grain harvests, domestic animals and other commodities, which were collected and redistributed to the population and to the gods.
"These are cultures that had an impressive ability to memorize lots of stuff, but there was a limit to that," says Snell. "A colleague of mine says that cuneiform was like an ancient zip drive. When they needed more memory, they had to figure out a way to store it."
Podany says that the people who first invented writing wouldn't have thought they were inventing writing, at least not writing in the way that we think of it. All they wanted at first was a system for keeping track of commodities and numbers, not to convey complex ideas or poetry.
Over time, though, the flexibility of that original cuneiform script was adopted by different ancient cultures and languages (Sumerian, Akkadian, Babylonian, etc.) and was employed for increasingly complex forms of expression, including ancient literature ("The Epic of Gilgamesh") and law (Hammurabi's Code).
The Wheel Also Got Rolling Here
If writing wasn't enough, there's also evidence that the wheel was invented around the Uruk period. Interestingly, the very first wheels weren't used for transportation, but for making pottery.
"The pottery from the Uruk period is the first to be thrown on a horizontal wheel," says Podany, which means that they were able to mass produce pottery in a way that wasn't possible before."
Historians don't know when, but at some point around the Uruk period someone got the bright idea to turn the horizontal potter's wheel on its edge and pair it with a cart, enabling the long-distance transport of commodities and people over land. Since those ancient wheels were made of wood, none of the early specimens survive, but Podany says that tiny wheeled carts made of clay — toys, perhaps? — have been recovered from Uruk and other sites in Mesopotamia.
60 Seconds in a Minute? Thank the Sumerians
More than 5,000 years later, we tell time using a number system invented by the Sumerians of ancient Mesopotamia. Today we use a "base 10" (decimal) system for most of our calculations, but the Sumerians relied on two other systems: "base 12" (duodecimal) and "base 60" (sexigesimal).
The number 12 makes sense, since the Sumerians were the first to figure out that there are 12 lunar cycles in a year and to divide the day and night into 12 periods (a precursor of the 24-hour day). Historians like Podany believe that 60 was such an important number to the Sumerians because it could be easily divided into so many whole numbers.
For example, if a mina (about a pound) of grain was worth 60 shekels in ancient Mesopotamia, then it was simple to come up with prices for half a mina (30 shekels), a third (20 shekels), a quarter (15 shekels), a fifth (12 shekels), a sixth (10 shekels) and a tenth (6 shekels).
The use of base 60 was passed down over the millennia from the Sumerians to the Babylonians to the Greeks to medieval Islamic scholars and finally to Europe, where the first clocks with second hands weren't invented until the 16th century.