By Bryan Lufkin16th June 2017
It’s been called the ‘next oil’. In the coming decades, the supply of water has the potential to influence geopolitics, diplomacy and even conflict.
GRAND CHALLENGES
In this special series, Future Now takes a close look at the biggest, most important issues we face in the 21st Century.
For two months, we’ll bring you insight from leading scientists, technologists, entrepreneurs and influencers to help you make sense of the challenges we face in today’s rapidly evolving world.
The 2008 James Bond film Quantum of Solace pits 007 against an evil criminal syndicate bent on global domination. Sounds par for the course… but this particular network of baddies isn’t using lasers or missiles to cause havoc.
No, the Quantum organisation has a uniquely dastardly plan: seizing control of Bolivia’s water supply.
While the evil syndicate’s role in the film might not be entirely realistic, this piece of fiction does raise a scenario that is worth considering seriously: what would happen if a country’s water supply was cut off? What would be the global fallout?
Think about it: sure, we need water to survive. But it also fuels a country’s commerce, trade, innovation and economic success. This has been the case for time immemorial, from the Nile in Ancient Egypt to the Amazon in the Brazilian rainforest.
While bodies of water typically help form natural borders of countries, several nations tend to share access to rivers or lakes – the Nile runs through nearly a dozen countries alone, for example. Given how conflict-prone humankind is, it’s surprising there haven’t been more dust-ups of a “hydro-political” nature.
Bodies of water have always formed natural boundaries between countries, forcing people to figure out ways to share water peaceably. (Credit: Getty Images)
Experts agree: if there was no access to water, there would be no world peace. That’s why one of the grand challenges of the next few decades could be maintaining this ultra-sensitive stasis of water management. In the 21st Century, freshwater supplies are drying up, climate change is raising sea levels and altering borders, explosive population growth is straining world resources, and global hyper-nationalism is testing diplomatic relations. Meanwhile, water demand is expected to go up 55% between 2000 and 2050. In the coming century, in terms of its value as a global resource, it’s been described as “the next oil.”
So what can we do to guarantee global access to water – and thus global peace?
World peace hinges on hydro-politics
Water’s role in shaping politics goes back centuries. “In the ancient world, large bodies of water formed natural boundaries for people and nations,” says Zenia Tata, executive director of global development and international expansion at XPrize, an organisation that’s holding a worldwide competition for innovative water management solutions. “But today’s geopolitical landscape looks very different,” and access to water remains paramount.
Experts agree: if there was no access to water, there would be no world peace
In many areas of the world, bodies of water run through several countries or brush up against many countries’ borders. That’s where something called “riparian water rights” come into play.
In the case of a river, upstream countries – where the river originates – enjoy inherent power and leverage over the downstream countries. These kinds of riparian hotspots abound. And they’re often in places that are already fraught.
In the Middle East, the Jordan River basin is the primary water source for many regions, including Jordan, Palestine, and Israel, regions of long-standing political tensions. In Syria, meanwhile, the worst drought in close to a millennium has been partly blamed for the country’s generation-defining civil war and radicalisation that led to the formation of so-called Islamic State.
Egypt and Ethiopia have sparred over development of water from the River Nile for centuries: the iconic river originates in Ethiopia but ends in Egypt, which sets up an inherently combative relationship. In 2015, Egypt and Ethiopia put enough differences aside to construct the Grand Ethiopian Renaissance Dam on the river, which is Africa’s largest dam and is due to open in July. The countries also signed a deal that strives to ensure fair river access.
Tata points to many developed or emerging markets that have had similar challenges: “Take the example of Malaysia’s 99-year deal with Singapore, giving them paid access to fresh water from the Johor River,” Tata says. “Singapore is arguably one of the most progressive nations on our planet, but without sufficient fresh water resources within its boundaries, all industry, trade, commerce and culture would all stand still.”
The answer might lie in how countries with more food and water export those supplies to other countries
According to the Pacific Institute, a California-based water resource information nonprofit, there have been dozens of water-related conflicts worldwide from 2000BC to present day.
So how do we make sure everyone gets enough water – and thus keep relative world peace in the 21st Century? The real answer won’t lie in countries controlling others’ water supply in what’s been dubbed so-called “water wars” – rather, the answer might lie in how countries with more food and water export those supplies to other countries.
Droughts and climate change will make water-fuelled diplomacy a crucial exercise in the 21st Century. (Credit: Getty Images)
Divvying up water supplies
While there have been many “water-related” conflicts over the millennia, there have actually been very few in terms of sending water over national boundaries.
There are three main issues when it comes to water in the 21st Century, says Aaron Wolf. He’s a professor of geography at Oregon State University who specialises in water resource management and environmental policy.
The first issue is the most obvious: water scarcity. A lack of safe, reliable water kills as many people worldwide as malaria and HIV/Aids, he says.
The second issue is the political implications of that scarcity. For example, in Syria, that history-making drought drove more people to cities, saw rising food prices, and exacerbated tensions in the country that already existed. They ended up with “climate refugees”, who travel to other countries to seek places that have better water availability, which may in turn stoke the flames of political tension.
The third main issue – and perhaps the most underreported, experts say – is that trans-boundary flow of water. In other words: water moving between countries. And that’s where those riparian rights come into play.
But here’s the twist – that third part of the puzzle, the hydro-politics, is actually the part to be most optimistic about, says Wolf, since there have been so few violent skirmishes over transboundary water flows.
Countries with a water surplus export “virtual water” around the world – water embedded in products like wheat and meat. (Credit: Getty Images)
The grand challenge: building hydro-diplomacy
Despite alarmist headlines about “water wars”, the 21st Century is still offering up no shortage of new and unique threats that complicate hydro-diplomacy more than ever before.
Population explosions, especially in Asia and Africa, strain resources. Increasing global temperatures have led to some bodies of water drying up. And rising nationalism worldwide may stymie diplomatic efforts across the board.
While water presents obvious potential conflict, it could also accelerate global cooperation
So that’s why at Oregon State University, Wolf helps organise the Program in Water Conflict Management – where they try to identify where hydro-diplomatic tensions are going to rise in the next three to five years. For example, Afghanistan is an upstream country to many nations in the region, and is trying to use that advantage to develop its economy. For a country that’s been subjected to decade upon decade of war and upheaval, the political power of water sources like the Kabul River could be a boon.
That’s why there’s growing academic desire for an increased awareness of not just hydro-politics, but hydro-diplomacy – that while water presents obvious potential conflict, it could also accelerate global cooperation.
“We’re building the next generation of hydro-diplomats,” says Wolf.
A solution? Pay farmers more
But amid all these changes in the aqua political landscape, experts urge us to remember that not all water exists in rivers and lakes and even oceans.
There’s water in the soil – the soil that farmers use to grow vegetables, crops and feed for livestock. And the water from that soil is transferred into these products – whether it is wheat or beef – before they get shipped from water-surplus nations to deficient ones. This is known as “virtual water”, a phrase coined by John Anthony Allan at King’s College London, whose specialities include water issues, policy and agriculture. “Virtual water” is going to play a huge role in the 21st Century.
Governments stay in power by subsidising farmers’ livelihoods, and water-deficient countries gladly import the under-priced food. (Credit: Getty Images)
If you include virtual water in the picture, farmers are managing much of the water in the supply chain. And in countries that are water deficient, that imported embedded water is integral. In Europe alone, 40% of this “virtual water” comes from outside the continent.
Here’s the problem: farmers are underpaid for the critical role in that transaction. And by the time the food reaches the destination country, its politicians use subsidies to keep food prices low. The reason? Politicians want to maintain peace among their people – they want their citizens to live under the assumption that they’ll be able go to the store and expect food on the shelves.
160 countries depend on imported food – and the water needed to make it
“Governments go to great lengths to make sure there is enough affordable food on the market,” Allan says. “There are forces in places that will bring the prices down – there’s pressure to keep food cheap.”
For water-surplus countries like the United States or Canada, they sell these products to more water-deficient countries at a low price. Over 60% of the around 220 countries in the world are major food importers. In other words, 160 countries depend on imported food – and the water needed to make it.
“The world is at peace because we have virtual water trade,” says Allan. “It’s solved silently. Revealing virtual water trade as a solution is something that politicians don’t want to do because they want to appear as they’re managing their country well.”
But in reality, the water that goes into the country’s food is being brought in from elsewhere. That’s why hydro-diplomacy is one of the great unsung heroes in maintaining global stability that you never hear about.
It’s also why water’s next big challenge isn’t just making sure it’s judiciously and peaceably managed between nations to accommodate the world’s ever-burgeoning population. It’s about helping farmers who live in nations that have lots of water do their jobs successfully, and manage that water and how it’s distributed to drier places.
Of course countries need low-priced food, especially in places with lower income citizens. But the public needs to know that imports, exports, and hydro-diplomacy are what really keep countries with imbalanced water sources in balance. In our globalised, 21st Century world, it’s not just about where countries fall along the flow of a river. It’s about working together to share Earth’s most vital resource.
So while a James Bond-scale water hostage situation isn’t exactly realistic – there’s nothing unrealistic about needing to maintain worldwide access to water. Even as we use it to slake our thirst and grow our crops, the political power of water shouldn’t be forgotten. It’s been around for millennia, and it’s not going anywhere.
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Bryan Lufkin is the editor of Future Now. Follow him on Twitter @bryan_lufkin.
When the Ever Ace, one of the largest container ships in the world, eased out of Yantian port on 14 August last year and manoeuvred gingerly into the South China Sea, she had embarked upon a record-breaking voyage.
To date, no other ship has carried such a large volume of shipping containers – the equivalent of 21,710 20ft (6m) containers.
The 399.9m-long (1,320ft) and 61.5m-wide (203ft) vessel is a true behemoth, but there are dozens of container ships of a similar size sailing today. Many more are currently under construction. Just two of them stacked vertically would be nearly as tall as the world’s tallest building, the Burj Khalifa in Dubai.
If you cast your eyes over a list of the largest container ships in the world, you’ll soon notice that they are all 400m (1,320ft) in length or just less than that, and about 60m (200ft) wide. It is more or less today’s upper limit for these vessels. There is a surprising number of reasons as to why – and also why you’re unlikely to see any container ships much larger than this, perhaps ever. But what are they?
There are around 5,500 container ships globally and together they are capable of carrying 25 million TEUs, or the equivalent of around 25 million 20ft (6m) containers. That’s if they were all fully loaded at the same moment.
As George Griffiths, editor of global container markets at S&P Global Platts explains, the global order book for new container ships will increase that total collective capacity by a gigantic 25% in just a few years.
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“We’re seeing a lot more of the ultra-large container ships being built,” he says. “The proportion of new ships that are moving over 14,000 containers is staggering.”
In the last decade alone, the average capacity of a container ship has grown from less than 3,000 TEUs to around 4,500 TEUs. And there are currently more than 50 ships with a capacity of 21,000 TEUs or more. Practically all of them were built in the last five years.
If ships become bigger, they may not be able to use waterways such as the Suez Canal (Credit: Camille Delbos/Art In All of Us/Getty Images)
However, these vessels stretch the limits of even the world’s largest ports, says Griffiths. To load and unload containers, cranes must reach across the vessels. Container ships also have to turn, pass through locks and canals – including the Suez and Panama canals, which have size restrictions.
It’s crucial that vessels avoid running aground, too. In some ports, the largest ships actually sit so deep in the water that they touch the bottom and glide through the silt rather than float above it, says Stavros Karamperidis, head of the Maritime Transport Research Group at the University of Plymouth. Such a manoeuvre must be handled with extreme care.
To accommodate ships much larger than the biggest in existence today would require a huge overhaul of port infrastructure. And that would be incredibly expensive, notes Griffiths: “Why would you invest in bigger ships if it means you have to invest eye-watering amounts of money in the ports as well?”
Karamperidis adds that the largest ships are also restricted in terms of where they sail because they are so vulnerable to heavy weather. They don’t tend to cross the Pacific, for example, which can hurl violent storms at vessels. Medium-sized container ships sometimes lose hundreds of containers in the Pacific.
“That’s why the [ultra large] vessels come near the coast, so they don’t face big waves. It’s a matter of stability,” says Karamperidis. He adds that most US ports are not big enough to facilitate the largest container ships. Only a handful of ships with capacities approaching 20,000 TEUs have ever called US ports.
You may be noticing a theme. The limitations on vessel size are not so much to do with the sheer engineering challenges of building really big ships but rather the economics and logistics of operating such giants.
As ships get bigger, they stress the capacity of even the biggest ports (Credit: ProPIC/Getty Images)
“Physically, there’s not really any limit,” says Rosalind Blazejczyk, managing partner and naval architect at Solis Marine Consultants. She does, however, note there are only so many containers that one could stack on top of one another on a ship before the container at the bottom of the pile would buckle under the weight.
Containers are also lashed to hold them in place and such systems have upper limits for the number of boxes they could secure safely, notes John Simpson, Blazejczyk’s colleague at Solis.
Another issue is how these very large and wide ships handle waves. When sailing directly into a sequence of waves, ships can experience a phenomenon called parametric rolling. It happens because, as the waves pass along the length of a very broad container ship, her bow and stern may clear the water whenever the peak of the wave is at the midpoint of the ship. This leaves the upper part of the bow and stern lacking the support of the water below. The variation in this support as waves continue to pass can cause the ship to bob weirdly from side to side.
Oil is exceedingly high at the moment and the largest container ships require huge volumes of fuel
“You get very large roll angles with not very large wave heights,” says Blazejczyk.
Supersized ships are more at risk of this. And container ships also have very large hatches on their decks, which means their overall structure is weaker than some other vessels and more susceptible to torsion, or twisting.
“They’re kind of like a shoebox with no lid,” Blazejczyk adds. No problem in calm seas but, again, limiting when or where a ship sails likely also limits its usefulness.
Besides all of the above reasons, there is economic weather to contend with. Griffiths notes that the price of oil is exceedingly high at the moment and the largest container ships require huge volumes of fuel.
Investing in even bigger vessels might not be the wisest financial choice in the future though, having said that, at the moment these costs are being more than covered by the astronomical freight rates worldwide. Such is the present demand for moving goods around.
Containers have to be lashed onto the deck of ships, which limits the amount which can be carried (Credit: Richard Ross/Getty Images)
Karamperidis says that, for container ships with a capacity much higher than 25,000 TEUs to become viable, the economics of operating them would have to change. The Suez Canal will probably always act as a bottleneck for ships travelling from Asia to Europe but it’s not impossible to imagine a 30,000 TEU vessel or similar one day traversing a route from China to, for example, a booming African port, says Karamperidis.
“Maybe we’ll see those kind of vessels going from Asia to Mombasa,” he adds, referring to the largest port of Kenya.
The 24,000 TEU ceiling on container ship capacity we see globally today is, more or less, a reflection of economic limits as much as it is about port infrastructure, the shape of the world’s busiest waterways and engineering.
But there’s always that possibility that, given the right conditions, someone somewhere with enough money will one day commission a vessel that dwarfs even today’s gargantuan ships. It would certainly be a wonder to behold.
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ASK A STUPID QUESTION | PHYSIOLOGY
The surprising benefits of fingers that wrinkle in water
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(Image credit: Neil Juggins/Alamy)
The skin on our fingertips and toes shrivels like prunes when soaked for a few minutes in water. But is this an adaptation that occurred to help us in our evolutionary past? And what can it reveal about your health today?
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Spend more than a few minutes soaking in a bath or paddling around a swimming pool and your fingers will undergo a dramatic transformation. Where there were once delicate whorls of lightly ridged epidermis, engorged folds of ugly pruned skin will now be found.
This striking change is familiar yet also baffling. Only the skin on our fingers and toes wrinkle when immersed in water, while other body parts such as our forearms, torso, legs and face remain no more crinkled than before they were submerged.
This water-induced wrinkling of skin on our fingertips and toes has occupied the thoughts and work of scientists for decades. Most have puzzled over what causes this puckering in the first place, but more recently the question of why, and what purpose it may serve, has attracted the attention of researchers. Perhaps more intriguing still, however, is what our shriveled fingers can reveal about our own health.
It takes around 3.5 minutes in warm water – 40C (104F) is considered the optimal temperature – for your fingertips to begin wrinkling, while in cooler temperatures of about 20C (68F) it can take up to 10 minutes. Most studies have found it takes around 30 minutes of soaking time to reach maximum wrinklage, however.
Fingertip wrinkling was commonly thought to be a passive response where the upper layers of the skin swelled as water flooded into the cells via a process known as osmosis – where water molecules move across a membrane to equalise the concentration of the solutions on either side. But as long ago as 1935, scientists have suspected there is more to the process than this.
Doctors studying patients with injuries that had severed the median nerve – one of the main nerves that run down the arm to the hand – found that their fingers did not wrinkle. Among its many roles, the median nerve helps to control so-called sympathetic activities such as sweating and the constriction of blood vessels. Their discovery suggested that the water-induced wrinkling of fingertips was in fact controlled by the nervous system.
The skin on our feet and hands shrivel and wrinkle in the bath, while other parts of our body do not undergo the same transformation (Credit: Andrii Biletskyi/Alamy)
Later studies by doctors in the 1970s provided further evidence of this, and they proposed using the immersion of the hands in water as a simple bedside test to assess nerve damage that might affect the regulation of unconscious processes such as blood flow.
Then in 2003, neurologists Einar Wilder-Smith and Adeline Chow, who were working at the National University Hospital in Singapore at the time, took measurements of blood circulation in the hands of volunteers as they soaked them in water. They found that as the skin on the volunteers’ fingertips began to wrinkle, there was a significant drop in blood flow in the fingers.
When they applied a local anesthetic cream that caused the blood vessels in the fingers of healthy volunteers to temporarily constrict, they found it produced similar levels of wrinkling as water immersion.
“It makes sense when you look at your fingers when they go wrinkly,” says Nick Davis, a neuroscientist and psychologist at Manchester Metropolitan University, who has studied fingertip wrinkling. “The finger pads go pale and that is because the blood supply is being constricted away from the surface.”
Wilder-Smith and his colleagues proposed that when our hands are immersed in water, the sweat ducts in our fingers open up to allow water in, which leads to an imbalance in the salts in our skin. This change in the salt balance triggers the firing of nerve fibres in the fingers, leading to the blood vessels around the sweat ducts to constrict. This in turn causes a loss of volume in the fleshy area of the fingertip, which pulls the overlying skin downwards so that it distorts into wrinkles. The pattern of the wrinkles depends on the way the outermost layer of skin – the epidermis – is anchored to the layers beneath it.
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There have also been suggestions that the outer layers of skin may also swell a little to enhance the wrinkling. By osmosis alone, however, our skin would need to swell by 20% to achieve the wrinkles we see in our fingers, which would leave them hideously enlarged. But when the upper layers of skin swell slightly and the lower levels shrink at the same time, the wrinkling becomes pronounced far sooner, says Pablo Saez Viñas, a biomechanical engineer at the Technical University of Catalonia, who has used computer modelling to examine the mechanism.
“You need both to have normal levels of wrinkles,” he says. “If you don’t have that neurological response, which happens in some individuals, wrinkles are inhibited.”
But if wrinkling is controlled by our nerves, it means our bodies are actively reacting to being in water. “That means it is happening for a reason,” says Davis. “And that means it could be giving us an advantage.”
Water-induced wrinkles may have given our ancestors better grip when walking on wet rocks or foraging for shellfish (Credit: Alamy)
It was a question from one of his children during a bath about why their fingers had gone wrinkly that recently led Davis to dig into what this advantage could be. With the help of 500 volunteers who visited the Science Museum in London during 2020, Davis measured how much force they needed to use to grip a plastic object. Perhaps unsurprisingly, those with dry, unwrinkled hands needed to use less force than people whose hands were wet – so their grip on the object was better. But when they submerged their hands in a water bath for a few minutes to turn their hands wrinkly, the grip force fell between the two even though their hands were still wet.
“The results were amazingly clear,” says Davis. “The wrinkling increased the amount of friction between the fingers and the object. What is particularly interesting is that our fingers are sensitive to this change in the surface friction and we use this information to apply less force to grip an object securely.”
The object that Davis’ volunteers were gripping weighed less than a couple of coins, so the amount of grip required was small. But when performing more arduous tasks in a wet environment, this difference in friction could become more important.
“If you don’t have to squeeze as hard to grip something, the muscles in your hands get less tired and so you can do it for longer,” he says.
His findings match those by other researchers who have found that the wrinkling of our fingertips makes it easier for us to handle wet objects. In 2013, a team of neuroscientists at Newcastle University in the UK asked volunteers to transfer glass marbles of varying sizes and fishing weights from one container to another. In one case the objects were dry, and in the other they were at the bottom of a container filled with water. It took 17% longer for the participants to transfer the submerged objects with unwrinkled fingers than when they were dry. But when their fingers were wrinkled, they could transfer the submerged marbles and weights 12% quicker than when their fingers were wet and unwrinkled. Interestingly, there was no difference in transferring the dry objects with wrinkled or unwrinkled fingers.
There are other baffling mysteries – women take longer to develop wrinkles than men do
Some scientists have suggested that the wrinkles on our fingertips and toes may act like rain treads on tyres or the soles of shoes. The channels produced by the wrinkles help to squeeze water away from the point of contact between the fingers and an object.
This suggests that humans may have evolved fingertip and toe wrinkling at some point in our past to help us grip wet objects and surfaces.
“Since it seems to give better grip under water, I would assume that it has to do with either locomotion in very wet conditions or potentially with manipulating objects under water,” says Tom Smulders, an evolutionary neuroscientist at Newcastle University who led the 2013 study. It could have given our ancestors a key advantage when it came to walking over wet rocks or gripping branches, for example. Alternatively, it could have helped us when catching or foraging for food such as shellfish.
“The latter would imply it is unique to humans, whereas if it’s the former, we would expect it to happen in other primates as well,” says Smulders. Finger wrinkling has yet to be observed in our closest relatives in the primate world such as chimpanzees, but the fingers of Japanese macaque monkeys, which are known to bath for long periods in hot water, have been seen to also wrinkle after they have been submerged in water. But the lack of evidence in other primates does not mean it doesn’t happen, it may simply be because no-one has looked closely enough yet, says Smulders. “We don’t know the answer to this question yet.”
There are some other interesting clues about when this adaptation may have appeared in our species. Fingertip wrinkling is less pronounced in saltwater and takes longer than it does in freshwater. This is probably because the salt gradient between the skin and surrounding environment is lower in saltwater, and so the salt imbalance that triggers the nerve fibres is less dramatic. So, it could be an adaptation that helped our ancestors live in freshwater environments rather than along coastlines.
But there are no firm answers, and some believe it could just be a coincidental physiological response with no adaptive function.
Only one other primate has so far been found to have water-induced wrinkling of the fingers – Japanese macaques (Credit: Benjamin Torode/Getty Images)
Strangely there are other baffling mysteries – women take longer to develop wrinkles than men do, for example. And why exactly does our skin return to its normal state – normally after 10-20 minutes – if there is no clear disadvantage to our grip on dry objects of having wrinkly fingertips? Surely if having wrinkly fingers can improve our grip in the wet, but not harm it when dry, why would our fingertips not be permanently wrinkly?
One reason for that could be the change in sensation the wrinkling also causes. Our fingertips are packed with nerves, and the pruning of our skin changes the way we feel things we touch (although one study has shown it does not affect our ability to discriminate between objects based on touch).
“Some people have a real aversion to it because picking something up with wrinkly fingers feels weird,” says Davis. “It could be because the balance of skin receptors have changed position, but there could be a psychological dimension too. It would be fun to investigate why. There could be other things we can do less well with wrinkly fingers.”
But the wrinkling of our fingers and toes in water can reveal key information about our health in surprising ways too. Wrinkles take longer to form in people with skin conditions like psoriasis and vitiligo, for example. Patients with cystic fibrosis experience excessive wrinkling of their palms as well as their fingers, and this has even been noticed in people who are genetic carriers of the disease. Patients suffering from type 2 diabetes also sometimes show markedly decreased levels of skin wrinkling when their hands are placed in water. Similarly reduced wrinkling has been seen in people who have suffered heart failure, perhaps due to some disruption in the control of their cardiovascular system.
Unsymmetrical wrinkling of the fingers – where one hand wrinkles less than the other despite the same immersion time – has even been suggested as an early sign of Parkinson’s disease as it indicates the sympathetic nervous system is not functioning correctly on one side of the body.
So, while the question of why our fingers and toes began wrinkling in water in the first place remains open, our pruney digits are proving useful to doctors in other surprising ways.
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Why your favourite colour is probably blue
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By Mark Ellwood3rd June 2022
From a young age we are primed to choose a favourite colour, but strangely as we grow up our preference often changes – and it’s largely due to influences outside our control.
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In 1993, crayon-maker Crayola conducted an unscientific, but intriguing poll: it asked US children to name their favourite crayon colour. Most chose a fairly standard blue, but three other blue shades also made the top 10 list.
Seven years later, the firm repeated its experiment. Again, classic blue ranked in the top spot while six other shades of blue appeared in the top 10, including the delightful sounding “blizzard blue”. They were joined by a shade of purple, a green and a pink.
The dominance of blue in such lists doesn’t surprise Lauren Labrecque, an associate professor at the University of Rhode Island who studies the effect of colour in marketing. Like a Pantone-sponsored party trick, she’ll often ask students in her classes to name their favourite colour. After they respond, she clicks on her presentation. “I have a slide already made up saying ‘80% of you said blue’,” Labrecque tells them. She is usually right. “Because once we get to be adults, we all like blue. It seems to be cross cultural, and there’s no big difference – people just like blue.” (Interestingly, Japan is one of the few countries where people rank white in their top three colours).
Our selection of a favourite colour is something that tends to emerge in childhood: ask any child what theirs is and the majority – crayon in hand – will already be primed to answer. Infants have broad and fairly inconsistent preferences for colours, according to research. (They do show some preference for lighter shades, though.) But the more time children spend in the world, the more they start to develop stronger affinities to certain colours, based on those they have been exposed to and the associations they link them to. They are more likely to link bright colours like orange, yellow, purple or pink to positive rather than negative emotions.
One study of 330 children between 4-11 years old found they used their favourite colours when drawing a “nice” character and tended to use black when drawing a “nasty” character (although other studies have failed to find such links, so emotional associations and colour are far from straightforward). Social pressures – such as the tendency for girls’ clothes and toys to be pink – also have a strong effect on colour choice as children get older.
Despite the wide array of crayons on offer, children will often reach for a preferred colour time after time (Credit: Alamy)
It is commonly believed that as children enter their teenage years, their colour choices take on a darker, more sombre hue, but there isn’t much academic research to support this. Adolescent girls in the UK, for example, have been found to be attracted to purples and reds, while boys favour greens and yellow-greens. One study of British teenage boys’ choice of bedroom colour found they tended to choose white, while they listed red and blue as favourite colours.
These colour palettes seem to converge as people grow into adulthood. Intriguingly, while the majority of adults say they prefer blue colours, they’ll likely also dislike the same colour too: a dark yellowish brown is routinely identified as least popular.
But why do we have favourite colours? More importantly, what drives those preferences?
Put simply, we have favourite colours because we have favourite things.
At least that’s the gist of ecological valence theory, an idea put forward by Karen Schloss, an assistant professor of psychology at the University of Wisconsin-Madison in the US, and her colleagues. Her experiments showed that colours – yes, even beige – are far from neutral. Rather, humans layer meaning onto them, mostly drawn from our subjective histories, and so create high personal reasons to find one shade repellent or appealing in the process.
“This accounts for why different people have different preferences for the same colour, and why your preference for a given colour can change over time,” she says. As new associations accrete – whether through everyday exposure in the world around us or artificially by deliberate conditioning – this can cause what we love to change over time.
Think of colour preferences as a summary of your experiences with that colour: your regular daily experiences in the world influence that judgement – Karen Schloss
Schloss finessed this theory via several experiments, including one at the University of California-Berkeley. She and her collaborators showed volunteers squares of colour on a screen while prompts asked them to rate how much they liked them. Then the researchers stepped away, as if to suggest a new experiment was starting.
They returned to show those same volunteers coloured images again, except this time, instead of plain squares, they saw objects. Each image was dominated by one of four shades. Yellow and blue-heavy images were used as the control: these depicted neutral objects, like staplers or a screwdriver. Red and green photographs, however, were deliberately skewed. Half the participants saw red images that should have evoked positive memories, such as juicy strawberries or roses on Valentine’s Day, while the green images they were shown were designed to disgust, such as slime or pond scum. The other half saw a set that reversed these associations: think red raw wounds versus green rolling hills or kiwi fruit.
Running the colour preference test again, Schloss and her team saw a change in preference. Volunteers’ choices had shifted towards whatever colour had been positively emphasised while there was little decrease for the negative shade. The next day, she brought them back and ran the tests again, to see whether that preference endured overnight – it didn’t. The shift induced by the experiment appear to have been over-ridden by the colours participants experienced out in the real world, according to Schloss.
“It tells us that our experiences with the world are constantly influencing the way we view and interpret it,” Schloss says. “Think of colour preferences as a summary of your experiences with that colour: your regular daily experiences in the world influence that judgement.”
Schloss’s work on colour preferences may also inadvertently go some way to explain blue’s position as such a widespread favourite. Blue’s reign has continued uninterrupted since the earliest recorded colour studies, which took place in the 1800s. And most of our experience with the colour are likely to be positive, like idyllic oceans or clear skies (“having the blues” is an idiom restricted to English). In the same vein, her work also offers a clue for why that muddy brown colour is so reviled, associated as it is with biological waste or rotting foods. For a brief period each year, though, this shade finds favour, largely thanks to changes that occur in the natural world.
Perhaps surprisingly, our preference for colour changes as we get older, largely due to our experiences in the world around us (Credit: Melpomenem/Getty Images)
In an experiment intended, at least in part, to unpack whether favourite colours were a static component of someone’s identity, Schloss and her team asked volunteers in New England to track their colour likes and dislikes weekly during the course of the four seasons of year. Their opinions seemed directly influenced by nature, with likes or dislikes rising and falling in sync with nature’s palette. “As the colours of the environment were changing, their preferences were increasing,” she says. The greatest uptick came in autumn, when warm colours – think dark red and orange – earned heightened plaudits, before tumbling at the same time as the leaves.
Asked to speculate as to why autumn saw such a surge, she suggests two explanations. First, the area where she conducted that research is famed for its autumnal displays – leaf-peeping is a tourism staple in New England – so volunteers might have been primed for that preference. More intriguingly, though, she also believes that there’s an evolutionary aspect in play – the sharpness of contrast. “It’s fascinating to speculate perhaps it’s because it’s kind of quick, this rapid, dramatic change to the environment – so fast, and then it’s gone. Winter is a lot of white and brown, but we’re not outside as much to see it.”
The environment we live in nudges our colour preference in other ways too. Another study Schloss conducted looked at students at University of California-Berkeley and Stanford, showing that the varsity colours of a college influenced the hues they picked as favourites. The more a student said they endorsed and embraced the values and spirit of the school, the higher that preference rose.
It’s a big misconception that babies can’t see colour from birth – Alice Skelton
It’s easy to assume that the ecological valence theory would need time to take hold, for us to embed those social cues in the world we see. But experimental psychologist Domicele Jonauskaite says that’s wrong. She studies the cognitive and affective connotations of colour at the University of Lausanne, Switzerland, and has looked at how boys and girls view blue and pink – they articulate, and demonstrate, learned colour preference at a young age.
Girls’ love of pink forms on a bell curve, peaking at early school age – around five or six – before dropping off by the time they’re teenagers. “But the boys avoid pink from an early age, at least five or so. They think ‘I can like any colour – just not pink’. It’s really rebellious for a boy to like pink,” she says. “And among adult men, it’s hard to find someone who’ll say, ‘pink is my favourite’.”
Some researchers in the past have proposed that this particular colour preference, anchored in gender, is evolutionary: women were the gatherers in hunter-gathering societies, that theory goes, and would therefore need a preference for colours associated with berries. That’s utter rubbish, says Jonauskaite, who cites several recent papers looking at colour preference in non-globalised cultures – villages in the Peruvian Amazon, for example, and a foraging group in the northern reaches of the Republic of Congo. None of their female children displayed a preference for pink. “In order to have this preference, or dislike, for boys, that aversion needs to have a coding of social identity,” she says. In fact, pink was seen as a stereotypically male colour prior to the 1920s and only became associated with girls midway through the 20th Century. (Read more about the pink-blue gender preference myth.)
Even the youngest children can perceive, and rank, colour, suggests Alice Skelton, who helps run the Sussex Colour Group & Baby Lab, at the University of Sussex in the UK. Her particular area of interest is in babies and children, aiming better to understand how early preferences in colour translate into aesthetic preferences later in life. “It’s a big misconception that babies can’t see colour from birth – they can,” she says, noting that the eye’s development is uneven. The receptors which perceive greens and reds are more mature at birth than those which process blues and yellows, so intense reds, in particular register most easily in newborns. 
If your choice of colour makes you stand out from the crowd, it could say something about how sensation seeking you are (Credit: Alamy)
The ecological valence idea – that we yoke meanings onto colours from the objects we encounter in the world – holds true even among the youngest. “Children will only pay attention to colour when it has a function associated with it. They won’t really pay attention to colour unless they learn something from that,” Skelton says.
Imagine there are two bottles. One is green, the other is pink. The green-coloured bottle contains tasty liquid, the pink one is a sour mix. Children will note, and remember, those colours, because recognising their difference provides a cognitive bonus. “It’s like a ripe banana – colour is a useful cue to some property of an object,” says Skelton.
That ripe banana, of course, could be a yellowish-brown, the same shade that squeamish adults tend to shun in laboratory tests. Skelton offers solace to anyone whose colour preference doesn’t fit the domineering rule of blue. Those drawn to unpopular shades could be products of a particular period, cherishing positive memories from their childhood – think 1970s babies snuggling on bouclé brown sofas. But there’s another intriguing possibility. Most humans are drawn to visual harmony, pleasure, and to easy sensations evoked by often-positive blue.
“It might be that while some are trying to achieve homeostasis, other people are sensation seekers, much like people are larks and night owls,” she says. “Think about artists, whose main job is to look for stuff that challenges their visual system or aesthetic preference.”
They’re the ones, doubtless, who didn’t reach for the blue crayon.
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