First suggested in ancient Greece, the four 'humours' personality types have shaped how we view ourselves for thousands of years – and still look oddly familiar today.

If you've ever watched or read Shakespeare's late 16th-Century play The Taming of the Shrew, you'll be familiar with the antiquated gender tropes at play.

The famous story centres on protagonist Petruchio, who exacts various punishments on his headstrong wife Katherine to transform her into an "ideal" pliant and submissive woman.

But modern audiences may be less aware of the diagnosis for Katherine's intolerable wilfulness: an excess of yellow bile (known as "choler") rushing in her blood, leading to a stubborn and hot-headed disposition. Yet more bizarrely, treating the affliction involves Petruchio preventing Katherine from eating "hot" foods that might further inflame her condition. Beef served with mustard, for instance, is strictly off limits.

While baffling to an audience today, humoral theory, which these ideas stemmed from, was a hugely popular framework for understanding health and personality in Shakespeare's time – and for millennia before him.

In addition to irascible "cholerics" like Katherine, there were depressive "melancholics" who suffered a surfeit of black bile; "phlegmatics" (gentle and sedate types who were flooded with phlegm) and "sanguines" (bounding, good-natured extroverts who were suffused with plenty of hot blood, something their ruddy cheeks supposedly attested to).

First originated by scholars in ancient Greece, the theory remained influential up to and including the Enlightenment period. It dictated health and lifestyle advice including which foods people should eat, which medical treatments they should undergo, and even where they should live, all according to their humoral type. The theory faced mounting challenges over the 16th and 17th Centuries, for example with the rise of dissection, greater understanding of the blood circulatory system and the invention of the microscope. Even so, it only faded away gradually.

And while the biological assertions have long been discredited – we aren't all, blessedly, overflowing with bile and phlegm – some of the theory's fingerprints can still be seen on scientifically based psychological models today.

The roots of humoral theory lie in the thinking of Greek pre-Socratic philosopher Empedocles (494-434 BCE), who first proposed that the classic four elements – earth, water, air and fire – were the building blocks of the universe. It is the Greek physician Hippocrates (460-370 BCE), however, who is typically credited with developing the theory of the four humours (yellow bile, black bile, phlegm and blood) and how they impacted the body.

A few centuries later, Greco-Roman philosopher and physician Galen (131-201 AD) codified the theory and described the four temperaments as an expression of the balance of temperature and moisture in the body.

Galen and Hippocrates' texts birthed a millennia-spanning obsession with temperature and moisture in the body, food and wider environment. These were thought to correspond to the four elements and the four seasons, as well as different stages of life. Melancholics were thought to be cold and dry, and associated with earth, winter and old age. Sanguines, hot and moist, were associated with air, spring and adolescence. Cholerics, hot and dry, were redolent of fire, summer and childhood. And phlegmatics, cold and moist, were related to water, autumn and adulthood.

Appearance was important to identifying someone's humour. "To a very large extent, complexion indicated the humour that dominated in........

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