Final answer:
The main reason for the small demography of hunters and gatherers is their complete reliance on natural resources, which naturally limited population growth due to the precariousness of food availability.
Step-by-step explanation:
The ecological base of hunters and gatherers is based on a relatively small demography because of a complete reliance on natural resources. In the context of hunter-gatherer societies, their population numbers were generally in check due to the limited amount of food produced by their environments which prevented significant population growth. While the lack of medical knowledge and the risks of warfare also contributed to their mortality rates, the key determinant for their small populations was the direct dependency on the immediate availability and regenerative capacities of their natural resources. Hunter-gatherer societies had to move and adapt to new areas when resources became scarce, demonstrating their strict bond with the environment as a means of survival.