Physicians and surgeons are natural enemies. It is nothing personal: just as the lion circling for the kill affords its wildebeest prey no malice, the mutual antagonism between surgeon and physician is simply a law of the medical jungle. The antipathy that each group holds for the other is submerged in the shallow waters of professional courtesy, but when, on occasion, the true feelings of either tribe breaches the surface, the medical student initiate may be in for quite a shock. On the outside, relations might appear quite amicable — matey even — but try this experiment: ask your student whose next rotation is with a surgeon to casually drop the term “evidence-based medicine” into the conversation in the operating theatre.

Look, I’ll admit this up front — some of my best friends are surgeons. I have shared their table, been on holiday with them, coveted their new convertibles and drunk too much of their 18-year-old single malt whisky. But the fact remains that when diagnostic push comes to therapeutic shove, I am one of “us” and they are one of “them”.

In the second year after entering the workforce, young medical graduates are faced with a crucial decision: will they become surgeons or physicians? In theory, there are dozens of other vocational choices (general practice, psychiatry, pathology, radiology and emergency medicine, to name a few), but for the surgeon and physician, these other paths are hardly worth considering — the “real” doctors, they believe, have only a dichotomous choice. Sometimes, the novices are unable to make up their minds and are submitted to a number of vocational aptitude tests, including being asked to comment on the following scenario:

It is, of course, a trick test. If the students haven’t made up their minds before they take the test, then they’re not meant to be surgeons. If they laugh, they can’t become pathologists. If they look up the meaning of “Anserini” then their die is cast as physicians.

Do you become a physician because you can’t make quick decisions, or do you choose surgery because, when young, you liked working with the family’s sewing machine and power tools? Was Ben Casey your role model or that lovely Dr Welby? Do you pine for McDreamy or fantasise over Greg House? In other words, are surgeons and physicians made or are they born? Let’s examine this question.

It would be reasonable to believe that surgeons require a degree of manual dexterity, yet some are among the clumsiest people I have ever met. One surgeon I knew often arrived at work on Monday with his hands bandaged, having injured himself with his woodworking tools. Another was notorious for losing things — keys, phones, computers, medical documents, two wives and, on one famous occasion, his children. In fact, I have never detected a strong association between talent in the theatre and hand–eye coordination out of it. Most skills of surgery are specific to the operating theatre, and a clumsy-ish person can probably make a decent surgeon. Having said that, I have no doubt that the “gun” surgeons, the ones who other surgeons would allow to operate on them, do have special physical abilities. And there are some subspecialties for which fine motor coordination is a prerequisite. The neurosurgeon and the plastic surgeon must bring a naturally steady hand to the operating theatre; a fine tremor is manageable in the abdominal cavity, but will not do in the unforgiving space of the brain.

There’s no prescribed height or weight for surgeons. They come in all shapes and sizes, with one exception — the orthopaedic surgeon. Here is an example of genetic inevitability: what’s bred in the bone really does come out in the medical flesh. The orthopod is an archetype best summed up in the song by the legendary Captain Matchbox Whoopee Band, surely familiar to the discerning reader of a certain age — “Six foot six, broad shoulders, what a whacker!” Outliers in this specialty exist only to prove the rule.

If physicians are the thinkers of the profession, then it follows that their ilk should all be gifted scholars. But the young doctors I shepherd through postgraduate training are mainly of solid intellect — more Watson than Holmes. Some are brilliant, but only a very few possess Mensa-level IQs, and this genius often displaces other personality traits such as empathy and humour (the latter being defined as the ability to find my jokes constantly amusing).

Physicians pursue a difficult diagnosis by taking a meticulous history and thoroughly examining the patient. They pride themselves on their understanding of pathophysiology and the social determinants of disease. The traditional hallmark of physicians is their ability (and desire) to consider the patient as a whole. These attributes may now be in decline; the interventional specialties, such as cardiology and gastroenterology, have attracted a whole generation of, well, surgeonly physicians who, in some cases, seem more inclined to consider the patient as a hole.

Another crucial difference between our two species was summed up by the artist formerly known as Cat Stevens: “The first cut is the deepest”. The surgeon must have the guts to go boldly with a scalpel where no one has (usually) gone before. There is no turning back once you are inside the peritoneal cavity — too late to say, “On second thoughts . . . ” The surgeon must be naturally decisive, prepared to make a call and stick with it. (And here is an important lesson for the young physician dealing with surgeons — remember that your conversation will not work if you try to engage in dialogue. Your physician’s desire for intellectual honesty and explicit depiction of the uncertainty of a course of action will be seen only as weakness.)

Surgeons don’t take long histories from their patients or do long ward rounds. In fact, many don’t seem to enjoy consulting much — surgeons like to operate. And if the answer to a problem is not immediately obvious, then it is time to call in the “clever doctors”. This is, of course, an ironic use of the term “clever”, for surgeons don’t really think that physicians possess any more skill or intelligence than they do. In their minds, the only thing that the physician has that the surgeon doesn’t is time. Surgeons are always busy, always somewhere else, or on their way to somewhere else. While the surgeon is doing the doing part, the physician is most likely reading a journal in a library somewhere or talking (yes, talking) to a patient. Physicians usually sleep in their beds at night; surgeons often sleep in their clothes.

Although they inhabit the same geographic space, physicians and surgeons live in different worlds. It is not unusual for a physician to pass a week without talking to a surgeon, and vice versa. One thing that can sometimes bring the tribes together is laughter. Walk into any hospital common room and you will find physicians telling jokes about surgeons and, across the corridor, surgeons telling jokes about physicians. And, on the rare occasions that they get together in the same room, surgeons tell the physicians jokes about orthopaedic surgeons. “What is the difference between an orthopaedic surgeon and a carpenter? The carpenter knows the name of more than one antibiotic.” “How do you hide something from an orthopaedic surgeon? Put it in a book.” Or my favourite: “Did you hear that we have employed a holistic orthopaedic surgeon? He cares about the whole bone and not just the fracture.”

Physicians, especially those who don’t perform procedures, are ever so slightly jealous of surgeons. They remember the fun they had when they were training, when they could get their hands dirty and do things that had an immediate effect on the wellbeing of their patients: the emergency tracheostomy for the man with an obstructed airway; the immediate relief for the woman following the drainage of her perianal abscess; the appendicectomy for the patient with the, er, normal appendix (OK, forget the last one). They pine for the uninterrupted hours that the surgeon can find in the operating theatre, where the existential thrill of operating insulates them, for a while at least, from the stress of the chaotic and uncontrollable world of the hospital. The physician can be envious of the elegant simplicity of surgery. “You need an operation”, says the surgeon to the patient, “I will do an operation”. The operation is done. “You are better now. Goodbye.” The physician must live with a series of much less conclusive interactions. “You have diabetes”, says the physician, “I will start you on insulin”. The insulin is injected. “You still have diabetes. See you next week (repeat).”

Every young person in the course of training to be a doctor dreams, at least for a while, of becoming a surgeon. Hardly any do. Surgeons don’t choose their career, surgery chooses them. Physicians? I’m not sure that the same vocational predetermination applies. Indeed (and it hurts me to say this), happy though your professional life may be, I suspect that sometimes a physician is what you became while you were making other plans . . .