What characteristic of sound waves is measured in units called decibels?

While humans have not changed much biologically in the previous 200,000 years, we live in vastly different cultural environments due to our cognitive capacity to formulate ways to change our environments.

a. true b. false

By age 2, a child's brain has

a. reached 50% of its adult weight. b. reached 75% of its adult weight. c. reached 90% of its adult weight. d. acquired all the neurons it will ever acquire.