Why does nature create patterns? A physicist explains the molecular-level processes behind crystals, stripes and basalt columns
Giant’s Causeway in Northern Ireland features around 40,000 exposed polygonal columns of basalt in perfect horizontal sections. Chris Hill/Photodisc via Getty Images
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Why does nature always create a pattern? – Saloni G., age 16, Alwar, Rajasthan, India
The reason patterns often appear in nature is simple: The same basic physical or chemical processes occur in many patterned substances and organisms as they form. Whether in plants and animals or rocks, foams and ice crystals, the intricate patterns that happen in nature come down to what’s happening at the level of atoms and molecules.
A pattern in nature is any regularly repeated arrangement of shapes or colors. Some of the most striking examples include the hexagonal arrays of rocks at Giant’s Causeway in the United Kingdom, the beautiful fractal arrangements of florets on a Romanesco broccoli and the colorful stripes and spots on tropical fish.
Each bud of a Romanesco broccoli bunch is composed of a series of smaller buds, arranged in a consistent spiral pattern. Creativ Studio Heinemann/Westend61 via Getty Images
Patterns like these begin to form at a small scale when materials undergo processes like drying, freezing, wrinkling, diffusing and reacting. Those changes then give rise to complex patterns at a larger scale that people can see.
Patterns in ice and rock
Imagine delicate frozen crystals on a windowpane during a cold day. What creates that pattern?
When water freezes, its molecules begin clustering together. Water molecules have a particular bent shape that causes them to stack into clusters shaped like hexagons as they freeze.
As the cluster grows, many outside factors, including humidity and temperature, begin to affect its overall shape. If the water is freezing on a windowpane, for example, small and random imperfections on the glass surface redirect the stacking and create the larger pattern.
Ice crystals on an old window in Norway. Baac3nes/Moment via Getty Images
This same process of stacking molecules is responsible for the striking variety of snowflake shapes.
What about the amazing patterns of the basalt columns at Giant’s Causeway? These formed 50 million to 60 million years ago, as lava – hot rocky fluid from deep underground – rose to the Earth’s surface and began to lose heat. The cooling caused the top layer of basalt to contract. The deeper, hot layers resisted this pulling, creating cracks in the top layer.
As the lava cooled, the cracks spread deeper and deeper into the rock. The particular molecular qualities of basalt, as well as the basic physics of how materials fracture apart – laws of physics universal to all substances on Earth – caused the cracks to meet up with one another at certain angles to create hexagons, much like the stacking water molecules.
Eventually, the cooling basalt broke into the hexagon-shaped columns of rock that still create such an impressive pattern millions of years later.
Patterns in animals
The creation of complex patterns in living organisms also begins with simple mechanisms at the molecular level. One important pattern-making process involves the way diffusing chemicals react with one another.
Imagine how a drop of food coloring spreads in a glass of water – that’s diffusion.
Drops of blue dye at different stages of diffusion in water. Science Photo Library via Getty Images
In 1952, English mathematician Alan Turing showed that a chemical spreading like this within another chemical can lead to the formation of all kinds of patterns in nature.
Scientists have proved that this process reproduces the patterns of a leopard’s spots, a zebra’s stripes and many other animal markings.
A tiger’s stripes can help it blend in with the surrounding environment – making it harder for prey to see. Sourabh Bharti/iStock via Getty Images Plus
What makes these markings consistent from generation to generation? As animal species evolved, these chemical reactions evolved with them and became part of their genetic codes. This might be because the markings helped them survive. For example, a tiger’s stripes camouflage it while hunting in a forest or grassland, making it easier to surprise and catch its prey.
However, researchers are still working out the details of which particular chemicals are involved.
Scientists do not always know the purpose of a pattern, or even if there is one. The molecular processes involved are simple enough that they might coincidentally generate a pattern.
For example, in my research team’s work studying plant pollen grains, we have seen a huge variety of patterns, including spikes, stripes and many more.
The pollen grains of various common plants like sunflower, morning glories, prairie hollyhock, oriental lily, evening primrose and castor bean – magnified 500 times and colorized in this image – display intricate patterns. Dartmouth Electron Microscope Facility
We don’t yet understand why a plant produces one particular pollen pattern rather than another. Whatever the ultimate use this and other patterns in nature may have, their variety, complexity and order are amazing.
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Maxim Lavrentovich receives funding from the National Science Foundation.
Polarpx // Shutterstock
There are 900 million acres of farmland in the United States, broken into more than 2 million farms. This accounts for approximately 40% of all acreage in the U.S.
Much of this farmland is used to raise livestock and grow corn and soybeans. But not all of it is used to produce foodstuffs for direct human consumption—a lot of it is used to produce food for livestock. This makes livestock and other animal production farms and facilities ancillary beneficiaries of U.S. farming. Agriculture, food production, and related industries (such as food manufacturing and retailing) were responsible for $1.055 trillion of the United States' gross domestic product in 2020—5% of the overall GDP.
To look at the environmental impact of domestic food waste, OhmConnect cited data from the EPA publication From Farm to Kitchen: The Environmental Impacts of U.S. Food Waste, released in November 2021.
One-third of all food produced annually is unconsumed and simply becomes waste. This also means that the resources used to produce that food in the supply chain—water, pesticides, gas or diesel used for freight and delivery, and energy for refrigeration—are also wasted.
The U.S. Environmental Protection Agency concluded that the U.S. wastes between 161 and 335 billion pounds of food per year, equal to anywhere from 492 to 1,032 pounds per person annually. To translate this figure into something most people are aware of and many actively keep track of, this equates to as much as 1,520 calories per person per day wasted, or enough food to feed 150 million people.
Food loss and waste per person increased over the last decade and tripled since 1960. Fruits and vegetables are among the foods that go to waste most often, and the consumption stage—typically at home or in restaurants—is responsible for approximately half of that waste.
Every type of food is wasted most during the consumption stage, which occurs in homes, restaurants, and other food service establishments. A 2020 study projecting the environmental benefits of cutting the U.S.'s food loss and waste in half found that addressing households, restaurants, and food processing would have the biggest effect on the environment, whereas addressing institutional food service or retail would have a minimal environmental impact.
According to Brian Roe, professor and faculty lead at the Ohio State Food Waste Collaborative, the average American family can put thousands of dollars of food in the trash each year.
An American Journal of Agricultural Economics study published in 2020 found the loss to be $240 billion in total in homes nationally, breaking down to $1,866 per household—though based on the most current U.S. Census' findings of the total number of U.S. households, that figure is closer to $1,961 per household.
Aleksandr Rybalko // Shutterstock
- Agricultural land wasted: 19,000 square feet
- Water: 19,000 gallons
- Pesticides: 2.5 pounds
- Fertilizer: 44.5 pounds
- Energy: 2,140 kilowatt-hours
- Greenhouse gas emissions: 1,190 pounds CO2
The issue with food loss and waste isn't just about what ends up in the trash can. It's about the loss and waste of everything that went into that potato, or banana, or onion—the water, the land, the pesticides, the fertilizer, and the energy add up to a greater, compounded loss.
To determine the environmental impact of food loss and waste, researchers consider how much food is lost or wasted, the type of food it is, and where in the supply chain it was wasted. The further along the supply chain food is wasted, the greater the impact on the environment because impacts are cumulative.
All told, the greenhouse gas emissions from one person's wasted food annually are equivalent to those from the average passenger car driving 1,336 miles. And the estimated water wasted is roughly what an average American household uses over the course of 63 days.
vchal // Shutterstock
Ninety percent of food wasted in the supply chain is edible, with inedible things like bones and shells making up the other 10%. Studies put the number of wasted calories per day between 1,100 and 1,520, a sizable portion of the recommended daily caloric intake.
This waste ends up in a landfill. According to the EPA, food waste is the nation's most commonly found material burned at landfills—it accounts for 24% and 22% of landfilled and combusted municipal solid waste, respectively.
North Americans waste more than three times what people waste in the Middle East, North Africa, Latin America, and the Caribbean, and more than 10 times what people in South Asia and sub-Saharan Africa waste.
When looking at food waste and loss by regional wealth, people in the U.S. waste 503 grams per person per day—196 grams more than those in other high-income countries. Food loss decreases as regional wealth decreases: People in low-income countries waste just 43 grams per person per day.
Country by country, the U.S. is surpassed by only two in the generation of food waste (China and India) and two in food waste per person (New Zealand and Ireland).
Fruits and vegetables make up 80% of all food loss and waste in sub-Saharan Africa and 64% of all food loss and waste in industrialized Asia. In North America and Oceania, they make up about half of all wasted food. According to the Food and Agriculture Organization, up to 60% of all fruits and vegetables find their way into landfills.
Some of the food waste is attributed to the financial, technical, and managerial constraints of producing food in countries with a less developed infrastructure, as well as underdeveloped food distribution networks and poor harvest and handling technology and techniques. These together result in billions of dollars in losses yearly. Much of the waste is also attributable to the demand for "perfect" fruits and vegetables.
Cutting the nation's food loss and waste in half could meaningfully conserve resources and reduce the environmental impacts of the food system, according to the EPA. By halving the food loss and waste across the country, the U.S. could lessen the environmental footprint by 3.2 trillion gallons of water as well as 262 billion kWh of energy—that's enough to power 21.5 million U.S. homes for a year.
This story originally appeared on OhmConnect and was produced and distributed in partnership with Stacker Studio.