Simplify the following text for a Grade 9 native English-speaking person.
Original: More abstract and theoretical arguments for the plausibility of the emergence of metabolism without the presence of genes include a mathematical model introduced by Freeman Dyson in the early 1980s and Stuart Kauffman 's notion of collectively autocatalytic sets , discussed later in that decade .
Simplified: Freeman Dyson introduced a mathematical model in the 1980s . Stuart Kauffman developed the notion of autocatalytic sets , which was discussed later in that decade .