Being a post-doc – the phase of existence that kicks in after surviving a Ph.D, – is more than just making a living: it’s a life. And the post-doctoral branch of life is unique – almost a separate species. In fact, it deserves its own place on the phylogenetic tree.

The life of post-docs (Homo postdocus) is dedicated to science, and they work almost constantly, seemingly oblivious to the many joys of the outside world. Post-docs generally appear quite unkempt, but as they rarely venture outside their laboratory environment, they pose no threat to other species. Indeed, post-docs are quite solitary, existing mostly in groups of two or less. Mating rituals are something of an enigma, as none has ever been reported (frankly, they don’t have the time).

The post-doctoral life cycle is relatively short, commonly three to five years, and for a lucky few, a dramatic metamorphosis into a completely different and much more prominent species, the Principle Investigator (PI, also known as the Assistant Professor or Group Leader) follows. The first subtle sign of this impending transformation is the loss of the strained look that inevitably accompanies even the most successful post-docs as they go about their day. This change is followed by the gradual shedding of their scruffy white coats, exposing smarter attire. To balance out the transient nature of the post-doc phase, their number are constantly replenished by young and naïve specimens known as Ph.D. students.

(The fate of the large group of post-docs that fail to make this transition is unclear, as even with sophisticated electronic equipment it has been impossible to track them all. However, there have been unconfirmed reports of trans-speciation into more common strains such as consultants or industry workers.)

There is a great deal of variation within the post-doc species – you have only to pass down the corridors of a university to see examples of each different type. In the middle of the night, the corridors are home to the Slave worker. Instantly recognizable by their gloved hands, they are bent over workbenches performing experiments for at least sixteen hours a day. If you’re lucky, you may see one of them going home, but formal evidence of this has yet to be documented. They are extremely solitary, and they hold a monopoly on most of the communal equipment, which makes them less popular with the other post-docs.

The library and other literary establishments provide a comfortable niche for the Visionary post-doc. This type is usually lost in thought, identified by deep lines in the middle of the forehead. They stand or sit almost motionless, pen in hand, and to the untrained observer may appear close to death. However, wait long enough and you may catch a rare glimpse of them furiously scribbling things that are incomprehensible to the rest of the Homo genus – as well as to most other post-docs. The Visionaries are also solitary creatures, but they cause fewer disturbances than the Slave workers as they remain stationary for long periods of time.

If you listen carefully, you will hear that most of the noise in the corridors comes from the Verbalisers. These Post-docs are the most social type, and are often found engaged in animated discussions. However, they tend to aggravate the Slave workers by interfering with their work, and the Visionaries by interrupting their thinking. They are otherwise well-tolerated, as they ensure effective intra- and inter-species information transfer, which is instrumental in procuring funds for propagation of the species.

Darwinian selection ensures that only the fittest specimens will undergo a successful post-doc-to-PI transformation. And it is known that certain geographical locations provide richer environments for increased survival. However, it has proven difficult to predict the precise conditions required for a post-doc-to-PI metamorphosis. From our primitive observations, it appears to be a combination of characteristics from all three of the post-doc types, often coupled to a persistent (some might call parasitic) relationship with an established PI. But the post-doc remains a fascinating species to observe because even with its uncertainty survival and below-Homo-average living conditions, it remains a dynamic and thriving population. And in any major city, as with the rat, you may be surprised to know that there is a post-doc living closer than you think.