Average work-week?

I remember being surprised to read that in the middle ages people worked about the same amount of time that we work today. That's nothin. Check this out:

Since the 1960s, the consensus among anthropologists, historians, and sociologists has been that early hunter-gatherer societies enjoyed more leisure time than is permitted by capitalist and agrarian societies; for instance, one camp of !Kung Bushmen was estimated to work two-and-a-half days per week, at around 6 hours a day. Aggregated comparisons show that on average the working day was less than five hours.