The earliest humans were hunters and gatherers, which as the name implies means that they got their food either by hunting wild animals and fishing or from gathering wild plants. This lifestyle does not afford a lot of control over the food supply as it relies on the group of people coming across the food they need to consume and though they would almost certainly have had strategies for how and where to search, or in the case of animals track them down, it still did not provide any certainties. It also requires the groups to move around a lot since the food sources would be depleted in an area after a relatively short time. It also did not allow the groups to grow too large since they would need to be kept small enough that a single area would support them all.
However about 12 thousand years ago people began experimenting with planting crops and staying in one place to tend them and later harvest these plants. This both allowed and indeed required communities to be settled. With selection of plants that yielded the most amounts of crops for future planting, the domestication of plants and agriculture had begun and with it the control of the food supply. This created a larger amount of food, which could support larger communities which led to early towns and even cities to be created and population density to rise. However, it also led to a less diverse nutrition since plants that were not so productive would not be cultivated, but would have been harvested and eaten by a hunter gatherer if they found them.
The surplus of food also allowed specialization since not everyone had to be directly involved in agriculture to produce enough food for the community. People could dedicate themselves to various crafts such as woodwork, fabric creation, etc. In the course of time these specializations became more and more specific.
Without the agricultural revolution society would never have become what it is today; we would never have been able to live as closely as we do or develop as we did since many of the things we developed over time required us to have a base.
However it also brought things such as widespread diseases, a greater emphasis on social status and conflicts between people.
For better or worse – and I would argue, it has both in abundance, the agricultural revolution has changed human life forever.
Scientifics are slightly geeky additions that have been with us since the eagle has known how to fly. Okay, not that long, but it's a nifty category that separates it from the usual ramble of articles.