>How is it possible to peer review a paper when the only people qualified to do so are the one's involved in the research. Seems like a massive issue.

Peer review isn't what it's chalked up to be. Basically it's two other people in the same field saying "There's no blatantly obvious issues with this paper" and even that isn't always guaranteed. Reviewers don't make any efforts to actually replicate the research, crunch the data, etc.