The critical factor, it seems, is the percentage of the population existing at a low caloric intake.  Starvation does some strange things

Standard personality tests revealed that the starving individuals experienced a large rise in the "neurotic triad" -- hypochondriasis, depression, and hysteria

Get a lot of people exhibiting hysteria and you get mass hysteria and then Moral Panic:

Moral Panics have several distinct features. The process by which these are created is best explained with Cohen's Deviancy Amplification Spiral:

    * Concern - There must be awareness that the behaviour of the group or category in question is likely to have a negative impact on society.
    * Hostility - Hostility towards the group in question increases, and they become "folk devils". A clear division forms between "them" and "us".
    * Consensus - Though concern does not have to be nationwide, there must be widespread acceptance that the group in question poses a very real threat to society. It is important at this stage that the "moral entrepreneurs" are vocal and the "folk devils" appear weak and disorganised.
    * Disproportionality - The action taken is disproportionate to the actual threat posed by the accused group.
    * Volatility - Moral panics are highly volatile and tend to disappear as quickly as they appeared due to a wane in public interest or news reports changing to another topic.

So one hand washes the other, as it where.

The reality of needing to stop starving leads to a condition favorable for Moral Panic which leads mass murder of a The Other along the classic time line:

Right Now:  the murders get to eat the food of the murdered

Short Term: the murders get the land of the murdered to crop food.  The living get a greatly increased daily food supply due to drop in demand.

Long Term:  no solution if the country doesn't use the time to build an economic system independent of subsistence agriculture.

She believed in nothing; only her skepticism kept her from being an atheist. -- Jean-Paul Sartre