According to Guns, Germs, and Steel, why does a sedentary lifestyle lead to an explosion of technology
You can find the answer to this question by reading in Chapter 13. Beginning on p. 260 in the paperback version of the book, Diamond discusses why sedentary people develop technology.
Diamond says that nomadic people cannot develop much technology because they are always moving. They can only have such technology as they can easily carry from place to place. For example, it would not be practical for nomads to carry clay pots around with them. When people settle down, they can develop and keep larger kinds of technology. Thus, a sedentary lifestyle makes technology practical and the onset of a sedentary lifestyle can lead to an explosion of technology.