The statement that best explains the difference between the two predominant theories of the origins of language is:
Some linguists believe that current languages were once joined in superfamilies, while Quentin Atkinson believes that all languages can ultimately be traced to Africa.
This statement captures the idea that many linguists propose a model where languages evolved from common ancestral languages (superfamilies), while Atkinson's theory emphasizes a single origin for all languages tracing back to Africa.