I do not understand this argument. Just as peer review is relatively young, so is the massive expansion of the scientific literature. Perhaps in the 50’s (when

I do not understand this argument. Just as peer review is relatively young, so is the massive expansion of the scientific literature. Perhaps in the 50’s (when there was peer review, at least in biochemistry and microbiology), an investigator might reasonably believe they were familiar with most of the literature in their field. That has not been true for decades. So, by volume (if not impact), most scientific results are young and have been subject to peer review. Perhaps part of the argument has to do with the specific form of peer review. In the 18th and 19th centuries, much more science was communicated via correspondence and books. But I suspect there was still a review process, just one that was less democratic and more dependent on reputation.