Changing fields in postdoc. Whether or not to pursue another postdoc at 35 This is my story. I did my PhD in neuroscience (took me 5 years), with no publications during my PhD, but got my PhD thesis published 2 years after graduation as a first-author Nature Medicine paper and a Nature Communications coauthorship. I also have a few other coauthorships in smaller journals. I had a very bad experience during my PhD, mainly due to my supervisor and neuroscience research dynamics in that particular field, so I quit science and took 10 months of holidays after my PhD (I was very depressed and had enough savings). Nevertheless I always loved science. For many years I have been interested in evolutionary genetics, and even during my PhD I was reading more on evolutionary genetics than on my own PhD field. By the end of my long holidays I got the opportunity to do a postdoc in evolutionary genomics in a small research group (this was 2 years ago). I was not convinced because I thought I would have a similar experience as during my PhD. Finally I took it. I learned programming, data analysis and bioinformatics from scratch, following tutorials on internet. Now I am extremely happy and I feel that I found what I was looking for all these years. We are about to publish a PNAS paper (where I am first author) and I am thinking in applying for another postdoc in this field in a big lab to start in 1 more year. I would really like to get a faculty position in this field some day, and I don't care if it is not in a top university (I also cannot, most likely). But I am 35 years old, so by the end of my second postdoc I could be 38-39. So my questions are:


Am I too old to start a second postdoc, considering my story?
How much can changing fields affect my chances of getting a faculty position in the middle term?


I am sure there are many people around the world with so different stories, so I would really appreciate to read some opinions.
Ask yourself what the trade-off is. There are basically three possible outcomes: (i) You quit now and do something else. (ii) You take the postdoc but don't get a faculty position after that, so do something else. (iii) You take the postdoc and do get a faculty position after that.

The way you describe it, you love doing what you do. So options (ii) and (iii) involve doing something you really enjoy, with the possibility of being able to do that for your entire life. In the worst case, you only get to do it for a few more years.

Options (i) and (ii) involve having to find a different job. The only reason why (ii) would seem to be a bad choice would be if you think that the job you can get after another postdoc is worse than what you could get now. But I don't really see why that would be so. So the long-term prospects for (ii) are no worse than for (i), but (ii) involves doing something you enjoy.