From my notes:
* Soviet collectivization. Inspired by huge mechanized farms in the US. Vision of doing for farming what assembly lines did for manufacturing. Both Soviet and US attempts to do so failed badly. Party resorted instead to martial law and grain seizures, creating peasant uprisings. Forcibly relocated peasants into standardized, pre-planned mega-farms which were ruled by agricultural specialists. Ignored local conditions, vastly over-simplified and over-abstracted different areas of land and differently-skilled populations. Pressure from above to deny failures led to plans quickly losing contact with reality. Peasants gained most of their food by farming their own private plots in their little free time. Peasants effectively became indentured slaves, stripped of any cultural institutions that might be a focal point for rebellion, and naturally responded with terrible productivity. More deaths from starvation that WW1 and civil war combined.
* Compulsory villagization in Tanzania. Similar story. Government (with support of the Western world) wanted to modernize the peasantry. Forcibly relocated peasants to standardized, pre-planned villages. (Was supposed to be voluntary, but top-down pressure for results led to initiative-taking). Peasants were moved vast distances, rendering their deep local knowledge worthless. (Peasants don’t come in standardized, fungible units). Forced to apply Western farming techniques which failed badly in the local climate and ecology. (The peasant practices of dense polycropping turn out to be much more effective in climates with high primary productivity than monocropping and ridging as is common in the West). Authorities heard reports of atrocities but insisted they were isolated cases.
* And again in Ethiopia. Lead to widespread famine.
Some, like in Ethiopia, were closer to ethnic cleansing -- deliberately moving people (esp from Tigray IIRC) who were violently unhappy with the government, to less fertile places where they didn't understand how to farm, especially with new crops to boot. But by claiming this was a modernisation scheme was excellent PR, people like those, and the resulting famine was seen primarily as a great tragedy, and brought in lots of aid money.
For russia I also like Yegor Gaidar, there's a book but the summary is http://www.aei.org/feature/the-soviet-collapse/
What people did with the resulting free time was generally to make war on those nearby.
But there have been many societies which
- didn't engage in agriculture at all, or
- engaged in tropical horticulture, which is low-effort
And those societies (plains Indians / Australian aborigines / sub-Saharan Bantu (they're farmers! But they're not labor-intensive farmers) / central Asian Turks and Mongols / etc. etc. etc...) are characterized by near-constant warfare.
Not all societies are ancestral to yours. Most aren't.
And seriously, claiming that a society will engage in warfare by comparing it to an example that is as remote to it as possible in terms of technological development and culture (we do view warfare as negative, not all societies do and ours used to not do so) is not exactly convincing.
The reason, if I understand right, was that the limit on human population was set by disease not labor. In northern climates (where fewer of the diseases we evolved with thrive) instead the marginal farmer was on some stony hillside from which maximum effort could only just produce enough calories for winter.
I'm less sure whether such societies were involved in more warfare, it's possible (the men had time on their hands & soccer hadn't been invented...) but I don't know the data.
I also don't know how to extrapolate this to the future of our society.
The first path was a mistake -- it looked modern, all those big machines, but was optimised for near-infinite land and very expensive labor. What poor countries typically had was the opposite: plenty of peasants and no room, and no diesel. So the winning strategy was actually closer to a million vegetable patches, with incentives, training, and transport to get this to the cities & export. An acre of vegetable patches can easily produce 100x the market value of an acre of wheat. Getting this right was a big part of how Taiwan & Korea for instance kick-started their growth. Getting it wrong was part of what killed the USSR -- if I remember right, they never even equalled the 1917 harvest.