In 1976, american anthropologist edward t. hall compared to an culture, ocean culture, iceberg social norms, ocean customs, iceberg

Edward T. Hall developed the Iceberg Model of Culture in 1976.  He hypothesized that culture was like an iceberg in that there were two kinds: internal and external. External is the outer manners of a society while internal are the principles, standards, and thought patterns underlying those behaviors. 

In 1976, American anthropologist Edward T. Hall compared behavior to an iceberg analogy of culture. He stated that if the culture of a society was an iceberg, then some aspects will be clear above the water but a large portion is hidden inside the water.

Explanation:

He designed the model of iceberg in which he placed the ‘Behavior’ on top, ‘Beliefs’ in the middle and ‘Values & thought patterns’ at the bottom (hidden portion). He explained his model between conscious and subconscious part.

The conscious (external) part is what we can see (top part) such as behavior and belief while subconscious (internal) part which includes values, thought and patterns is hidden.

the answer to your question is,

old stone age.

-mabel < 3