"Agriculture (a term which encompasses farming) is the art, science or practice of producing food, feed, fiber and many other desired goods by the systematic raising of plants and animals."

This is a general definition of agriculture. While there is some evidence for sporadic agriculture earlier, it is around 8500 BC that the first evidence of large scale cultivation of crops can be found.

This evidence is found at many sites in the Middle Eastern region. Does this prove absolutely that agriculture began no sooner than this? No. But it seems very likely, especially given that the spread seems to been fairly fast.

What gave rise to this inovation? Perhaps changing climate, including warmer temperatures and increased rainfall (keep in mind, the last Ice Age ended around 10000 BC).