In which year was the world's population 4 billion

The year gap of the population of 4 billion people was from 1974 - 1986. Exactly 12 years of 4 billion people.

answer; ///it examines the interaction between genetics and culture in shaping human biology;

one way archaeology us understand the past is through the material objects it finds, allowing us to know what was being used, and when. for example a dig recently found a flute, believed to be the oldest musical instrument found to date.

i hope this