Final answer:
Starvation due to poor nutrition and food shortages was NOT among the factors that led to the downfall of past horticultural societies.
Step-by-step explanation:
The factors that led to the downfall of past horticultural societies include reduced fallowing time leading to soil depletion, social stratification due to food surplus, and food surplus leading to population growth. Starvation due to poor nutrition and food shortages was NOT among the factors that led to the downfall of past horticultural societies.
Horticultural societies formed in areas where rainfall and other conditions allowed them to grow stable crops, which created food surpluses. These surpluses led to population growth and social stratification due to the accumulation of wealth. However, reduced fallowing time and soil depletion eventually contributed to the downfall of these societies.