The spread of agriculture in the Fertile Crescent is primarily due to a few factors: the Mediterranean climate, characterized by short, wet winters and long, hot, dry summers. This leads to the natural selection of annual species, which wither and die in the dry season; this, in turn, means the plant expends all its energy developing the fruit, without wasting it on developing a solid, woody stem. A second advantage is that the native species present are already highly productive. A third advantage is the presence of hermaphroditic selfers, or plants that self-pollinate, although they can occasionally do so with each other. Hermaphroditism is advantageous to the farmer because it prevents the plant from losing the artificially selected genetic trait, while occasional cross-pollination can produce a random mutation that can prove beneficial in the long run. A fourth advantage is the presence of large domesticated mammals such as goats, sheep, pigs, and cows. A fifth advantage is that fishing, hunting, or gathering are not very profitable in the Fertile Crescent, so there is no strong competition from nomadic hunter-gatherer cultures.
