Without enough people even subsistence farming falters to maintain sufficient nourishment. The maximum density figure used here is based on fire evacuation and room occupancy data used by fire Marshals in regulating the number of people who assemble in buildings. Clearly ten square feet per person would be an easier number to suggest crowded conditions, beyond which fire and health safety become critical issues of public concern. At ten square feet per person there would be no space for movement and since people are not trees such a density for humans is a temporary condition at best. People basically require a great deal more space than critics of demographic determinists have suggested.
Space is important to correctly convceive of in terms of the quantity of feet.
Consider the size of your height as the staring point in relation to ten feet. Space as the amount of distance separating objects in a field. Clearly they live in association with others, with animals and with common places whose area is used by others. So we can consider this as personal space, adjacent space for draft animals and common space used by the community. Considering the individual space and social areas that are necessary for humans to thrive, the figures below representing unrealistically dense populations are used for you to consider the implications of crowding in terms of temporary occupancy levels often used by fire marshalls to determine the size of rooms and number of exits per person required in those rooms for thier occupants to safely enter or leave the confined space.