Origin of lowdown?

English as a Second Language English Vocabulary, Grammar and Idioms
1

Hi, I know that lowdown means the inside truth about something but where does this word originate from?

2

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Well, I found this for the adjective:

[Early 20th century. < low down “very low” or low-down “contemptible”]

I guess that the noun (1915) followed on from the adjective (1850), though the meaning has diverged considerably.
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