THE gap between rich and poor began 7000 years ago when land became more valuable than people, suggests new research.

Farmers began using ox-drawn ploughs to harvest crops instead of their hands and the class system was born, according to the study. Researchers say that it enabled them to grow 10 times more cereals and vegetables without needing extra workers.

Those who owned land and ox teams also began to opt for more stress-tolerant crops, like barley or certain kinds of wheat, that didn’t require much labour. By the second millennium BC, in many farming landscapes, fields stretched to the horizon.

Societies were deeply divided between wealthy landowners, who passed their holdings to their children and land-poor or landless families.

Study co-author Professor Samuel Bowles, an economist at the Santa Fe Institute, New Mexico, explained: “Ox drawn ploughs were the robots of the late Neolithic.”

The oxen were a form of technology that separated wealth from labour – a fundamental development in the inequality we see today.

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Bowles said: “The effect was the same as today – growing economic disparities between those who owned the robots and those whose work the robots displaced.”

The findings, published in the journal Antiquity, add to growing evidence that lasting divisions between the haves and have-nots can be traced back to the Neolithic or late Stone Age. But it was kick-started by the first farming “machinery” rather than the change from a hunter-gatherer to an agricultural lifestyle, in itself.

The international team’s analysis of data from 150 archaeological sites across Eurasia revealed a steep increase in inequality from around 4000 BC.

This was about 8000 years after the advent of farming. They used statistical methods to compare different kinds of wealth, societies, regions and times.

Lead author Professor Amy Bogaard, an archaeologist at the University of Oxford, said: “The surprise here isn’t so much inequality takes off later on, it is that it stayed low for such a long time.”

The finding backs a previous analysis of 300 human skeletons by British scientists that suggested the concept of inherited wealth started with Neolithic man 7000 years ago.

Co-author Professor Mattia Fochesato, an economist at Bocconi University, Milan, said: “The usual story – that the societies that adopted agriculture became more unequal – is no longer valid because we observed some societies who adopted agriculture were remarkably egalitarian for thousands of years.”

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Before around 4000 BC, people across the Middle East and Europe cultivated a patchwork of small garden plots. They were like present day allotments in the UK, said Bogaard.

Families would have grown a variety cereal grains as well as lentils, peas, and other pulse crops that needed to be harvested by hand.

Notably, they would have tilled the soil by hand using hoes, in some cases also with the help of unspecialised cattle such as ageing milk cows to pull ploughs.