Contributorships Are Not 'Weighable' to be Equal

A new trend to assign some authors as 'first co-authors' is noticeable in scientific publications as a statement highlighting that two or more authors 'contributed equally' to a reported work. However, the requirements of scientific rigor, honesty, and accuracy in academic standards make such statements invalid and, thus, should be avoided. A potential solution is to specify the role of each co-author, from study conception to communication of results, and let readers judge the importance of each contribution by themselves. Alternatively, authors should demonstrate how they contributed 'equally' when they are defined as 'equal contributors'.