The most incredible facts about yellow

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Stylist Team
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Use these snippets of wisdom to nail your next pub quiz…

Why are Post-it notes and taxis yellow? What does the colour symbolise in different parts of the world? And where did the bright yellow smiley originate…? Here, Stylist answers all of your burning questions about this brightest of hues…

Why are Post-its yellow?

The original yellow Post-it colour was actually an accident. Dr Spencer Silver, a scientist at US company 3M, 
was researching adhesives in the late Sixties when he happened across one that stuck lightly to surfaces without gluing permanently. No one was interested in his discovery but he was persistent, borrowing scraps of yellow paper from the office next to his lab to illustrate how it could be used. It took a while to convince 3M that there was a commercial product in it but eventually it stuck (!) and Post-its are now sold in more than 100 countries.

What does the Italian word for ‘yellow’ mean?

Over in Italy, yellow translates to “giallo”, which is the name given to books and films in the crime genre – or more specifically, thrillers, horrors and mysteries. The name originated from a series of paperback books called ‘Il giallo Mondadori’, which were thrillers published in a bold yellow colour. They were mainly translations of books by British and American authors such as Agatha Christie and Edward Wallace, and it wasn’t long before the trend took over the whole country, with yellow books coming to symbolise mystery.

Why are taxis painted yellow?

Here’s a fact that makes sense as soon as you know it – taxis across the world are painted yellow because the colour is so easy to spot from a distance. This (literally) bright idea originated in Chicago in the early 1900s, when an entrepreneur called John Hertz decided to make his taxis bright yellow after a study by the University of Chicago recognised it as the easiest colour to spot.

Why can’t we “see” yellow?

Our eyes can’t actually “see” yellow. Yes, you read that right. Human eyes have trichromatic vision, which means we can only “see” the colours red, green and blue. It’s not until the signals reach our brain that we perceive the real colour. If you are looking at red and green, but not a lot of blue, then your brain tells you that you are seeing yellow.

Who’s responsible for the smiley?

The yellow smiley face has popped up in many places over the years. It’s one of the most popular emojis, it was a symbol of the rave scene in the late Eighties and early Nineties, and it was hugely popular in the Seventies, adopted into the mainstream from the hippy scene and used on T-shirts, keyrings and posters. But it actually has very humble beginnings. Back in 1963 in Worcester, Massachusetts, commercial artist Harvey Ball was commissioned by insurers State Mutual Life Assurance Company to develop a graphic to boost staff morale. Ten minutes later he had drawn the now-iconic yellow circle with black eyes and a line smile. And was paid just $45 (around £35) for it. 

What does the colour yellow mean around the world?

The colour yellow has vastly different meanings for different cultures across the world – and while some cultures associate it with positivity and optimism, others have branded yellow as the colour of mourning, or even pornography. In Western cultures, yellow is a summery colour with mostly positive associations – although in France, Italy and Germany, it’s often associated with envy.

In Egypt, yellow is the colour of mourning, although it has more positive associations across the rest of the Middle East. It’s also the colour of mourning in Latin America, although in Africa, yellow is known for being the colour of wealth and status. In Thailand, yellow is a lucky colour, while in Japan, it’s associated with royalty. In contrast, yellow is the colour most associated with pornography in China.

What happens when a leaf turns yellow?

During the spring
 and summer, leaves
 are filled with green chlorophyll, the
 biomolecule that allows them to process sunlight and turn
 it into sugars. When autumn comes there’s less sunlight and leaves start to fall to the ground. But before the leaves drop, any beneficial material
is reabsorbed by the tree.
The green pigment in the chlorophyll is broken into colourless compounds, revealing yellow pigments that have been there all along. has had a yellow makeover on 15 August, to celebrate our Yellow Issue and pay homage to the colour of the season. Read more about the most playful shade of all here.

Images: Unsplash