Simplify the following text for a Grade 9 native English-speaking person.
Original: One of the earliest incarnations of this idea was put forward in 1924 with Alexander Oparin 's notion of primitive self-replicating vesicles which predated the discovery of the structure of DNA .
Simplified: In 1924 , Oparin talked about primitive vesicles that replicated themselves . This was before the structure of the DNA was found .