When do researchers decide to be listed as last author?

Question

As I see, most if not all Ph.D. students strive to be listed as the first author of the research paper, then followed by coauthors and finally the Prof who is responsible for the lab.

While I am checking my professor previous publications; I noticed that over the last 30 years my professor name slides from being the first author to second and lately the last-mentioned name in the affiliation list.

For my understanding, the first author is always the person who contributed the most to the manuscript. So when/how do these professors decide to stop being first authors and be listed as the last author?

Answer 1

This depends a lot on the field, but for many sciences and engineering the following is (at least to some extent) true:

• The amount of work invested into the manuscript decreases with position in author list.
• The amount of responsibility/funding for the project increases with position in author list.
• If a publication has many authors, the ones in the middle are probably the ones with least significance.

The first author usually wrote the most of the manuscript and submitted it. These are PhD students. For some programs, first-authored publications are a requirement, therefore it is desired by many PhD students to get the first place.

The last author(s) are usually the supervisors and professors overseeing the research effort. They probably took part in discussions, maybe even drafted some text. In most cases, they just supervised the process/project. The "big boss" will most probably be the last, though.

For everyone in between, the contribution can be very diverse. It could be someone who did experiments, someone who helped by discussing the matter (mostly these people get an acknowledgement, not authorship) or in some cases even everybody who worked in the building.

Therefore, in an average academic career where somebody progresses from PhD student to professor, they will advance in the author list. This is because they do less practical work and more coordination and organisation. This is some kind of established system that has no written rules to it. I know of professors who demand they be the first author on every publication of their PhD students. While strange, it is not forbidden.

Answer 2

I think I can say that for all of my papers, I have contributed equally with all of my co-authors, and so the order of authors on my papers is not determined by how much work I have put in. Rather, I have always subscribed to the idea that the person who stands to gain most from it should be first author. In my case, given that I'm a full professor, I let my students and postdocs be first author (in all but a few of my papers). I've been doing this since I was an assistant professor -- I had my position secure and knew that I would get tenure, and so it was my job to make sure that others get the benefit from these papers.