Final Answer:
Because humans can walk on 2 feet, their hands were free to make tools and manipulate objects, which gave them an advantage over the other animals.
Step-by-step explanation:
Walking on 2 feet: The statement acknowledges the unique human ability to walk upright on two feet, a characteristic known as bipedalism.
Free hands for tool-making: The phrase "their hands were free" implies that bipedalism freed up the hands from the primary function of walking, allowing humans to engage in other activities.
Tool-making and object manipulation The statement suggests that one significant outcome of having free hands was the ability to make tools and manipulate objects. This is a crucial aspect of human evolution, as the development and use of tools played a pivotal role in shaping early human societies.