Some other studies of hunter-gatherer workloads are not as encouraging, at least on the surface. Since Lee’s data on !Kung work patterns were collected during the dry season, John Yellen (1977) studied a group of !Kung during the wet season. He found that during this time of year they worked considerably longer. In addition, Kim Hill, Hilliard Kaplan, Kristen Hawkes, and Ana Magdelena Hurtado (1985) found that men among the Aché, a hunter-gatherer society in Paraguay, spent perhaps 40 to 50 hours a week hunting. But this figure is probably highly atypical. Robert Kelly (1995) has presented data on the workload in eleven hunter-gatherer societies in five different world regions. These data show that the average amount of time both men and women spend foraging is only about 3.8 hours a day, which comes to slightly less than 27 hours a week (assuming that foraging is undertaken every day). If we calculate the total subsistence effort in these same eleven societies by adding in the amount of time people spend at such tasks as manufacturing and repairing tools and processing food, then people are spending only 6.5 hours a day (45.5 hours a week). This is well below the figure for the members of modern industrial societies, who work a 40-hour week and spend many more hours in such subsistence related activities as getting to and from work, shopping for food, cooking, and maintaining their households. Most interestingly, Bruce Winterhalder (1993) has shown that most hunter-gatherers must limit their subsistence efforts because failure to do so will be counterproductive. In most hunter-gatherer environments, if people work too hard they will deplete their resources and lower their productivity in the long run. As he notes, low to intermediate levels of effort are associated with the largest sustainable populations and the highest rates of food acquisition.