Measures of stability in agriculture 1. Standard deviation 2. All three of these have increased after the Green Revolution, suggesting that instability in food supply is increasing. Covariation across regions increases. Evaluation of Instability issue 1.
Pattern is complex and uneven, so that no single cause can given.
Genetic cause is probably not a factor yet, but it is possible. Overall increased food supply makes it possible to respond to instability at the local and regional levels, so that large scale famine is avoided by emergency food aid. Higher yields and integration are necessary, so that means to cope with instability have to be found. Use of HYVs eliminates landraces, causing genetic erosion and genetic vulnerability 3. Evidence exists for all three of these consequences.