Before that time period was the last Ice Age, which lasted for many thousands of years. The climate was so arid and difficult to survive in that it was not really possible for anyone to survive in one place long enough to discover & develop agriculture, since these groups of people were required to move around to be successful at hunting & gathering.

There has been no evidence found of any type of homonids knowing how to cultivate plants before the last Ice Age, in the previous warm period (the preceding interglacial), since only materials like bones and rocks can survive over such a vast amount of time. However, it is fairly safe to say that it is unlikely that they understood how to cultivate plants on a meaningful scale that early in their development. In addition, it is believed that there were relatively few homonids in the previous interglacial (the Eemian), so it is likely that the naturally-occurring amounts of plants and animals could sustain a small, thinly-spread population without plant cultivation being neccessary.

However, after the worst of the last Ice Age (the Last Glacial Maximum) was finished, the climate began to warm up to the point that our planet entered the current warm period called the Holocene. Over several thousand years, this reliable climate has allowed humans enough stable, warm weather to stop surviving by only hunting and gathering, and to settle down and discover new ways to survive, such as agriculture, animal husbandry and new technology.

As the human population slowly increased over the last several thousand years, the naturally-occurring amounts of food were not able to sustain the larger population, and much of the available arable land was occupied. Therefore, people found that it was increasingly desirable to aquire more food from their own land instead of fighting with other people (wars) over food supplies, so cultivation of plants became more and more necessary, causing the rise of agriculture in many different areas.