The answer to this can be found in Chapter 8. The long version of the answer takes up much of the early part of the chapter, roughly from p. 136 to p. 142 in the paperback edition of the book. The short answer is that the Fertile Crescent had a head start on the other regions of the world because it was much better for agriculture. This allowed it to have agriculture long before any other region of the world. Let us now look at a few reasons why it was better for agriculture.
First, it had a Mediterranean climate. This kind of climate is good for producing plants that are convenient for human beings to use. The Fertile Crescent was the world’s largest zone of this sort of climate.
Second, there were already large stands of usable plants growing wild. The stands would have been so big that they were obvious to hunter-gatherers.
Third, many of the plants of this region fertilize themselves but sometimes cross-pollinate. This is a sort of reproductive biology that is convenient for humans.
Fourth, there are a wide range of altitudes and topographies in a small area in the Fertile Crescent. This meant that crops could mature at different times in different places.
These are some of the important reasons for the Fertile Crescent’s “head start.” Please refer to the pages mentioned above for more details.