Is that true? I thought there was evidence for setrong divisions of labour as soon as agriculture came along. That brings surplus and, with it, social stratification.

A lot more people used to farm as a percentage of the population. Even in the last century, especially in communist countries where pay was low. Small subsistence farmers were much more common. You might own a small plot, and some pigs, cows an even a horse. Or if really poor work on someone else's land. Just being around animals exposes you to many more dangers, like getting kicked or even infections from cleaning waste.