A key element of the answer to Yali's question which dominates the book is the fact that hunter-gatherers are necessarily limited societies. The way that their lack of farming and agriculture necessitates the involvement of all of its peoples in hunting and gathering has the following impacts on societies, as demonstrated by the Chatham Islands as explained in Chapter Two of this great non-fiction work:
1) Population density is low
2) There are no developed economies
3) There are no expert craftsmen
4) There is no big system of leadership.
The difference between hunter-gatherer societies and societies that relied on agriculture to supply its needs are very notable, as the dispersed bands of hunter-gatherers were never able to settle in one location and thus this impacted population size. The number of people that can be supported by such a style of life compared to the number of people that can be supported by an agriculturally based society is much smaller.