How trade increases complexity in human societies

How do human societies get more complex?

It’s tempting to concentrate on a brilliant inventor, one who creates something totally new. That happens, of course. But more often, change is slow and is the result of lots of little steps. Even more often, new complexity is the result of something learned or imported from somewhere else.

Collective learning isn’t just about passing down knowledge to new generations. It’s also about spreading ideas and technology from one place to another. Once humans started farming and building cities, people living in those cities began to want things they couldn’t get at home. So they traded—they sold the stuff they had to people in other places who wanted it, and they bought the things they didn’t have from people in other places. Sometimes, the things made by people in one place were new or better, and other societies learned from it, improving their own products. But it wasn’t just goods. People also adopted new ideas from the societies they traded with—including ideas about government, science, religion, and culture. Trade made human societies more complex.

Trade meant that there was more stuff—and more different kinds of stuff—being made and moved around the world. As people with different goods and ideas met and mixed, cultures and religions grew larger and more complex, and technologies spread to new places and innovations sped up.

That’s why we need to talk about the Silk Road—the most important trade route in history. The Silk Road was a collection of land and sea routes stretching from China to the Mediterranean Sea. The most important type of goods traded along these routes was silk from China, but thousands of merchants traveled along these routes carrying many other types of goods to many different places.

The Silk Road is the oldest, largest network of trade routes in human history. Some facts about the Silk Road:

1. It was not actually a road. It was a huge network of many different land and sea routes stretching from eastern Asia to western Europe.
2. It existed since at least the Han Dynasty and Roman Empire.
3. It was used by many thousands of merchants, who traded goods with each other in a sort of relay race across big regions.

Where did the Silk Road come from?

Human societies have traded with each other since at least the Agricultural Revolution. People in cities traded goods made by artisans in exchange for food from farmers in the countryside. Farmers traded with herders and foragers. As more cities and states emerged, they traded with each other for things they couldn’t get at home.

Over time, trade routes generally became longer and longer, and more merchants used them. The rise of big empires made it easier to trade over long distances, because those powerful empires used their armies to make it safer for people to travel. They hunted down bandits and pirate and built watchtowers and rest stops along trade routes. Another factor that made big trade routes possible was the development of portable belief systems that connected people in shared faith and ethics across long distances. Religions like Islam, Christianity, and Buddhism made it possible to find someone who had a similar culture and values to you, which made it a bit easier to trade at the end of a long voyage.

The Silk Road came to represent the largest and longest trade route around 100 BCE for a couple of reasons. One reason was the geography of Eurasia. You’ll notice the routes of the Silk Road mostly go east-to-west and not south-to-north. That’s because if you go from east to west, the climate doesn’t change much. A long south-to-north route might take you from the hot equator to the freezing arctic. But the main routes of the Silk Road were mostly in the habitable middle temperature the whole way. They also had two other advantages: not having too many mountains to climb and not having huge oceans to cross. Of course, there is a big desert along the way, which is why camels were an important “technology” for merchants on the Silk Road. Camels could survive on little water while crossing dry areas. Ships were another key technology, since some paths were water routes in the Indian Ocean, Red Sea, and Mediterranean Sea.

But maybe the most important element in the development of the Silk Road was the presence of large, organized states. The routes of the Silk Road only really emerged in a period when four big empires controlled the whole distance—the Han Dynasty in China, the Kushans in Central Asia, the Parthians in Persia, and Rome in the Mediterranean. These states all wanted trade, and their soldiers made the routes safe for merchants.

What traveled along the Silk Road?

Most goods only traveled short distances along the Silk Road. These included food and tools traded from one community to the next. The goods that moved thousands of miles from Asia to Europe weren’t everyday foods or cheap junk. Every time an item changed hands from merchant to merchant, it got more expensive. So long-distance trade goods had to be stuff that people far away were willing to pay lots of money for. We call these luxury goods. Luxury goods were products that were expensive, easy to carry, and durable. No one wants to carry something heavy and breakable across thousands of miles only to lose money at the end. That’s why the most popular commodity that traveled the Silk Road was… silk.

Romans loved silk. In the first century CE, during the rule of the Roman Emperor Tiberius, silk was a symbol of great wealth. It was comfortable in the heat, could be dyed all sorts of colors, and felt good against the skin. So, as some Romans became wealthy, they wanted more silk. But silk wasn’t made in the Roman Empire. It was only produced far away to the east—in China. And the Han Dynasty worked hard to make sure the process of making silk remained a secret. Silk was the first major luxury item to go all the way along the Silk Road.

Yet, other goods also traveled long distances, and they were mostly goods of great value, such as precious metals like gold and silver, horses, gemstones, art, and spices like nutmeg, cloves, and pepper. The Romans were particularly good at making glass products, which they traded to the east.

These luxury goods were important in the ancient world, but the ideas and beliefs that traveled the Silk Road routes were even more important in shaping history. As they moved, merchants and other travelers brought their knowledge and beliefs with them. Their ideas often mixed with the cultures and technologies of the areas in which they arrived, which spread innovations to new places.

Unfortunately, diseases also moved along the Silk Road. Trade caused many big pandemics, like the Black Death of the fourteenth century. When this happened, or when an empire collapsed, the routes of the Silk Road shrank for a while. But they always grew again, because trade is just too important to human societies.

How did the Silk Road increase complexity?

Silk Road trade helped ideas and technologies spread so effectively that they changed the world. A good example from the ancient period is papermaking. Paper let people write down ideas and do calculations, which helped them spread and save ideas. Paper moved from China to Central Asia and later to Europe along the Silk Road. Religions, with their new ideas, also traveled. Christianity, which began in the Mediterranean world, reached the area just west of China by the seventh century CE.

In the medieval period, other technologies spread and changed the world. Gunpowder was developed first in China, but it reached the Islamic world and Europe in the fourteenth century, leading to a military revolution and helping to create bigger and more powerful empires. Chinese-style plows helped European peasants grow more food. Islamic and Greek ideas about medicine reached India and China traveling the opposite direction along those same routes.

By 1500, the Silk Road routes had helped Eurasian societies accumulate vast amounts of knowledge, which they applied to important projects. For example, the ships that left Spain and reached the Americas in 1492 combined sail technology from the Indian Ocean, Chinese compasses and gunpowder, and European hulls. The ideas that spread along the Silk Road transformed the world far from those routes and the impacts continue to unfold in the present.