One of the first and most productive scaling theorists was ____

Why was walking on two legs a useful adaptation?

a. It made running possible. b. It freed the hands to do other things (e.g., use a tool, carry food, etc.). c. It allowed for reaching things at a greater distance. d. It made hominids taller and more frightening to animals.

The heart of critical thinking is a willingness to actively __________ on ideas

fill in the blank with correct word