Read the sentence from “Rivers and Stories,” Part 1. It was probably fishing and hunting on floating logs that led to boat-making, and boat-making must have increased enormously the mobility of the species.

What does the author mean by the phrase “the mobility of the species”?

1-the ability of humans to live on the water

2-the ability of humans to learn how to build boats

3-the ability of humans to move from place to place

4-the ability of humans to find their own food