Countless students, around the globe, ask themselves this question every day. Not long ago, Antonio Marco was one of them but then he found his answer from an old source. Now, the evolutionary geneticist is a successful group leader at the University of Essex. Here’s his advice.

It wasn’t too long ago that I was preparing my PhD dissertation. The final year is hectic and on top you have to make a crucial decision on whether you will be doing a postdoc, or not. But the real question is: are you good enough to be a scientist? At least that’s what I asked myself several times before I made my choice. Almost by chance, I stumbled upon an old book written by Santiago Ramón y Cajal over a century ago. After I had read it, I decided I would pursue a scientific career. A decision I have never regretted.

The book I’m writing about is “Advice for a young investigator”, originally published in 1897. (The English version I use in this article is the translation by Swanson and Swanson, published by MIT Press in 2004.) Cajal is the father of modern neurobiology. Among many other things, he discovered that neurons are individual cells, he described dendritic spines, and even suggested that changes in synaptic connections are behind learning and memory.

But Cajal was also an excellent writer and storyteller. In this book, with the subtitle “The Tonics of the Will” (Los Tónicos de la Voluntad), Cajal describes how a young investigator should approach a scientific career. In the first part of the book he also identifies the four common traps that cause young investigators to abandon their careers. Strikingly, more than a century later, the following beginners’ traps are still the main reasons for students to leave science: undue admiration of authority, preoccupation with applied science, perceived lack of ability and thinking that the most important problems are already solved. Let’s have a look at them.

As students we are used to believing what a teacher tells us. If during a lecture you are told that a genome is composed of four types of nucleotides, you just believe it and write it down in your notebook to prepare for the forthcoming exam. Currently, students frequently believe that textbooks are compendia of demonstrated facts. In this context, students often think that what is in a book, or is told by a lecturer, is immutable. If you are taught that a genome only contains adenine, guanine, cytosine and thymine, it is impossible to argue against it. The problem is that this is not even true – other types of nucleotides exist at lower frequencies in the genome.

Challenging authority is not easy. But accepting authority as an argument leads to a well-known fallacy. The argument of authority goes as follows: person A is an authority in field X, person A makes a statement about X, person A must be correct. The problem comes when, for whatever the reason, person A is not correct (or is trying to mislead us). You can find plenty of examples. For instance, Mr Smith is a Medical doctor. Mr Smith says that smoking induces cancer. Mister Smith must be correct. Obviously, we trust Mr Smith because he is a doctor, so we don’t need to read any papers or reports about the incidence of cancer in smokers. That looks convincing.

What about this one? Mr Martin is a scientist. Mr Martin says that scientists have no evidence whatsoever supporting evolution. Mr Martin must be right. For some people that can be a strong argument. What I didn’t mention is that Mr Martin is a chemist who never worked in evolutionary biology. The point here is not whether Mr Martin is right or not (he isn’t), but whether we should trust his authority as a scientist to make such a statement.

Here’s a real (infamous) example. For centuries it was believed that women had fewer teeth than males. That statement goes back to Aristotle who said that this happened because men have more “heat and blood” than women. Aristotle’s writings were too authoritative to be challenged. It took someone to do the counting to realise that Aristotle was wrong.

When we believe everything our supervisor, or a teacher, or a textbook tell us, without questioning where this information comes from, we can end up developing an unhealthy admiration for authority. This is the ‘I will never be as good as my supervisor’ kind of feeling. The best way to avoid this snare is to talk about science and discuss papers with your colleagues early in your career. Journal clubs and discussion groups are excellent, to avoid developing an undue admiration for authority.