An article in the Wall Street Journal by Robert Lee Hotz describes the apparently inexorable increase in the number of authors of scientific papers.
In 2014 according to the Web of Science the number of papers with 50 or more authors reached over 1400 and the number with 500 or more was over 200. The situation is getting so bad that one journal, Nature, was unable to list all the autors of a paper in the print edition .
Hotz has an amusing digression where he recounts how scientists have listed a hamster, a dog and a computer as co-authors
One issue that he does not explore is the way in which multi-authorship has distorted global university rankings. Times Higher Education and Thomson Reuters until this year declined to use fractional counting of citations in their World University Rankings so that every one of hundreds of contributors was credited with every one of thousands of citations. When this was combined with normalisation by 250 fields so that a few citations could have a disproportionate effect and a deceptive regional modification that rewarded universities for being in a country that produced few citations then the results could be ludicrous. Unproductive institutions, for example Alexandria University, those that are very small, for example Scuala Normale Superiore Pisa, or very specialised, for example Moscow State Engineering Physics Institute, have been presented by THE as world leaders for research impact.
Let us hope that this indicator is reformed in the forthcoming world rankings.