Shawn Vestal: When cows were the cornerstone of income inequality

One of the earliest and most potent forces dividing the haves and have-nots may have pretty humble roots: the agricultural beast of burden.

An analysis of ancient archaeological sites worldwide by a team of researchers led by Washington State University’s Tim Kohler suggests that the advent of domesticated oxen, cattle and other large livestock coincided with sharp increases in wealth inequality.

For a post-Neolithic farmer in Mesopotamia, after all, the difference between owning oxen and not owning oxen was huge. Oxen dramatically expanded how much land you could plow and how much food you could grow. They produced a steady stream of rich fertilizer, increasing yields and helping create surpluses. That in turn helped create a baseline of wealth on which a farmer – and succeeding generations – could build more rapidly.

That, Kohler and his fellow researchers have posited, may be one big reason that premodern Old World societies in Eurasia became richer – and less equal – more rapidly than those in the Americas, where big farm animals did not appear until much later.

“The Old World had so many advantages because of the domestic animals,” said Kohler, professor of archaeology and evolutionary anthropology at WSU.

Kohler was the lead author of a paper published in the journal Nature late last year that compared archaeological data about house sizes in more than 60 societies in Eurasia and North America to look at wealth distribution.

This issue has particular pertinence now, and in this country, where income and wealth inequality are historically high. Lots of research suggests this is bad for a society generally – reducing economic mobility, worsening individual health and eroding a shared sense of purpose in democratic institutions.

Trying to peer backward in time to see how other societies distributed wealth can be difficult, since there aren’t written economic records. The study’s authors needed to find a way to measure wealth from the archaeological record in a way that could be made consistent across different societies and that represented the range of wealth in a society.

“House size is the one thing we could all measure with confidence and though it’s not perfect, it’s pretty good,” Kohler said.

The researchers evaluated data on Old World societies in Eurasia dating from 2,000 to 11,000 years ago, and from those in the Americas between 300 and 3,000 years ago. Using the distribution of house sizes, researchers calculated a Gini coefficient for each society and compared them at similar points in their evolutions. Gini coefficients measure inequality – a Gini coefficient of 0 would reflect a perfectly equal distribution of wealth, while a 1 would indicate one person owned everything.

Hunter-gatherer societies tended to be very equal in terms of wealth, with low Gini coefficients. Inequality began to grow with agricultural societies. The researchers measured the evolution of inequality of the different societies against how long those societies had engaged in agriculture.

As Kohler was writing what was to be a book chapter on the research, he stumbled across something unforeseen: Whereas the Old World and New World farming societies tended to have similar Gini coefficients for many years as they evolved, inequality shot up much more rapidly in the Old World societies after about 2,500 years of existence than it did in New World societies whose agricultural economies had been in place for the same amount of time.

“That was a big puzzle,” Kohler said.

The team proposed a possible explanation: large domestic livestock and the process of agricultural “extensification” in the Old World. Those societies had access to domesticated oxen, cattle and horses, unlike the New World. In addition to being valuable in itself, livestock represented a tool by which people could build future income and wealth, farming more land and building surpluses. Horses gave societies greater range and helped create a “warrior class” that could protect and expand power. Livestock could be inherited, so they helped create intergenerational accumulation of wealth.

And, because agricultural growth is “land-hungry,” the researchers note, as the Old World wealthy expanded their holdings, the class of landless peasants grew.

“These processes increased inequality by operating on both ends of the wealth distribution, increasing the holdings of the rich while decreasing those of the poor,” the Nature paper said.

The paper received a lot of worldwide attention, given the urgency of the issue of inequality. Kohler said that serendipity of discovering the differences in Old World and New World farming societies, and the beginning of inquiries into why that might be, is one of the things he relishes about his job.

“This is one of the joys of comparative research,” he said. “To find things you didn’t know before.”