When did the first humans appear in North America?

Humans first appeared in North America in 1950s. A hypothesis states that the Clovis culture represents the earliest human presence in the Americas, beginning about 13,000 years ago; evidence of pre-Clovis cultures has accumulated since 2000, pushing back the possible date of the first peopling of the Americas to 33,000 years ago.

where is the passage

answer; depression and breathing related sleep disorder(independent);