Alan Bennett ("A Plant Breeder's History of the World", Science, 23 July 2010, page 391), referring to the early ages of civilization, says, "Societies facing rising demands for crops found it harder to expand production than to conquer new lands or to encourage commerce; thus political investments favored the military and trade rather than agricultural improvement."
Bennett then goes on to comment, "Much changed during the 17th and 18th centuries."
Yet it seems to me that political investment continues to favor the military and trade. A review of the 20th century would certainly show increased investment in agriculture and food security, but my guess is that you'd be hard put to make a case that such investment swamped the privilege given to either military or trade investment by any society. Military investment has changed in character, in that conquering new lands was much reduced as a military objective; "conquering" market areas for tade largely superceded military conquest. Nevertheless, social investments in military and trade continue to be favored above other categories.
Plant breeding (the topic of Bennett's book review) and other aspects of improving food production have not lacked interest from political entities. Significant investments have been made. The history of the University of Wisconsin's College of Agriculture would make one case study to support that thesis -- or Iowa or any of many others. What agriculture and food security investment seems to have lacked is not interest but confidence.
Urbanization and industrialization in the United States was possible only because of the success of an agricultural revolution, but that revolution took something like 150 years to unfold (at least since the McCormick reaper of 1834) and often it was unclear how and how far the changes could extend. The Green Revolution of the late 20th century was more fuly strategized and more scientific but has similar uncertainty in its future prospects. Bennett's observation that "the returns from improving agricultural crops were far too slow to be widely appreciated" remains too close to the truth even in the 21st century.
Military options have likely been fully played out; I believe you could make the case that military investment in the future will yield diminishing returns on every metric. Investments in trade and commerce appear to be near or possibly beyond the peak of their value.
The open question is which replacement strategies societies should invest in. Should we build on plant breeding, expand agricultural reform, begin large-scale genetic engineering, or take some other approach? The game continues, but the strategy must change.