War! (Huh!) It is what it does! Potentially, the expansion of empires and the creation of complex social structures. Although it might not be a catchy tune, it summarizes an interesting new study published in Science Advances that suggests warfare may have been more important than agriculture for increasing social complexity.

Stable global temperatures have enabled us to settle down in permanent agricultural settlements since the Holocene began around 10,000 years ago. This has allowed for the division of labor as well as the development of more complex societies. It has triggered our evolution from hunters-gatherers to farmers and space travel sniffer persons.

Human history is more than watermelons or sunflowers. It’s also tragic that our species’ trajectory has been shaped by conflict. The study authors used the Seshat: Global History Databank to test the impact of war on the development of complex societies. This database is made up of historians, archaeologists and other experts who have studied past civilizations over the past ten thousand years.

The researchers consulted with scholars to identify 17 variables that impact sociopolitical complexity. They then developed an algorithm to determine which variable is the most important. The authors summarize their findings by writing that the “unexpectedly simple web” of causality was discovered. Agriculture and warfare are the main drivers of social complexity and scale.

They explain further that iron weapons and cavalries, which are the two most important factors in facilitating social complexity, have eclipsed all other factors. They explain, for example, that the first macrostates (polities with a greater than 100,000 km2 (38,600 miles) of territory) were created in Mesopotamia after the introduction of bronze metallurgy.

Bronze weapons were later combined to allow for large-scale empires that covered more than 3,000,000 square kilometers (1.2 Million square miles). These megaempires were created in each of the major Eurasian regions three to four centuries after the advent of cavalry.

Although it may seem like a long time, the researchers claim that military technology has enabled faster evolutionary change than the adoption of agricultural technology.

This study does not assume that warfare has increased cultural complexity within human societies. The authors found that military technology has triggered the expansion and complexity of three aspects of civilization. These are the area occupied by a society and the complexity of the ruling hierarchy. They also discovered the rise of specialized bureaucratic, legal, and administrative institutions.

Referring to the data, it seems that the maximum territory held in major empires has remained stable for roughly two millennia after the “IronCav Revolution”. To break this threshold of social complexity, it would be necessary to achieve another military milestone: the “Gunpowder Revolution”.

The study authors point out that the time lag between the appearance effective gunpowder guns and the rise European colonial empires was 300 to 400 years. This highlights a repeating pattern in which military innovation seems to be accompanied by the expansion of human civilisation.

The researchers conclude their report by pointing out that the analysis was not comprehensive. Further research into social complexity is needed to establish the true significance of war.

If these first findings are any indication, however, it seems that the dagger is more powerful than the cabbage in shaping human history.