Agriculture is of interest to us for two reasons: first settled agriculture contrasts with hunter-gatherer economies of the Pleistocene. Secondly, agriculture is the source of most of our food today.
1. Agricultural cf. hunter-gatherer economies
We mark the end of the Paleolithic and the beginning of the Neolithic about 10,000 years ago and the defining point is the transition from a hunter-gatherer economy to settled agriculture.
In fact, the transition occurred in seven independent places (including Syria and Papua New Guinea) 10,000 years ago and most of the rest of humankind continued as predominantly hunters and gatherers for thousands of years.
Another rarely acknowledged aspect of the transition is the way the settled, agricultural communities used their surplus to support a coercive transition to settlement, land ownership and agriculture on their neighbouring hunter gatherers.
We continued this coercive transition through the 20th century, most noticeably in Australia and the Australian Aborigines, like the indigenous peoples of North America are struggling now, in 2002, to come to terms with the notion of "civilization" which rests on the dominance of agriculture (and the cultural artefacts that accompany it) over hunter-gatherers.
There are still some isolated hunter-gatherer communities in the world today in 2002. The largest extant agglomeration is in the Indonesian province/colony of western New Guinea.
To come to an understanding of the cultural and historical significance of the transition from hunting and gathering to agriculture, I recommend the books of Daniel Quinn, especially "Ishmael", "My Ishmael", "The Story of B" and "Beyond Civilization".
2. Agriculture as the source of our food
I'm still working on this section. It will be based on the truth that we need Pleistocene food to achieve Pleistocene fitness.