Simplify the following text for a Grade 9 native English-speaking person.
Original: Reeve and Holldobler 's version of superorganism theory further elaborates this model by considering competition and co-operation between groups as well as within groups .
Simplified: Reeve and Holldobler have put forward a theory of a superorganism . They elaborate this model further , by also looking at competition and co-operation between groups as well as within groups .