Why does nature create patterns? A physicist explains the molecular-level processes behind crystals, stripes and basalt columns

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Why does nature always create a pattern? – Saloni G., 16 years old, Alwar, Rajasthan, India

The reason why patterns often appear in nature is simple: the same basic physical or chemical processes take place in many patterned substances and organisms as they form. Whether in plants and animals or rocks, foams and ice crystals, the intricate patterns that occur in nature are due to what happens at the atomic and molecular level.

A pattern in nature is any regularly repeated arrangement of shapes or colors. Some of the most striking examples are the hexagonal rock formations on Giant’s Causeway in the UK, the beautiful fractal arrangements of the flowers on a Romanesco broccoli, and the colorful stripes and spots on tropical fish.

Patterns like these begin to form on a small scale as materials undergo processes such as drying, freezing, wrinkling, diffusion, and reaction. These changes then result in complex patterns on a larger scale for people to see.

Patterns in ice and rock

Imagine delicate frozen crystals on a window pane on a cold day. What creates this pattern?

When water freezes, its molecules begin to clump together. Water molecules have a peculiar curved shape that causes them to stack into hexagon-shaped clusters when they freeze.

As the cluster grows, many external factors, including humidity and temperature, begin to affect its overall shape. For example, when the water freezes on a window pane, small and random bumps on the glass surface will redirect the stacking and create a larger pattern.

The same process of stacking molecules is responsible for the striking variety of snowflake shapes.

What about the amazing patterns of the basalt columns at the Giant’s Causeway? These formed 50 to 60 million years ago when lava – hot rocky fluid from deep underground – rose to the surface and began to lose heat. Due to the cooling, the top basalt layer contracted. The deeper, hot layers resisted this pulling and cracked the top layer.

As the lava cooled, the cracks spread deeper and deeper into the rock. Basalt’s particular molecular properties, as well as the basic physics of how materials break apart – laws of physics universal to all substances on Earth – caused the cracks to meet at specific angles to form hexagons, much like the one that meets them stacking water molecules.

Eventually the cooling basalt collapsed into the hexagonal rock pillars that still form such an impressive pattern millions of years later.

patterns in animals

The emergence of complex patterns in living organisms also begins with simple mechanisms at the molecular level. An important pattern making process concerns the way diffusing chemicals react with each other.

Imagine how a drop of food coloring spreads out in a glass of water – that’s diffusion.

In 1952, English mathematician Alan Turing showed that such diffusion of one chemical within another chemical can lead to the formation of all sorts of patterns in nature.

Scientists have proven that this process reproduces the pattern of a leopard’s spots, a zebra’s stripes, and many other animal markings.

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 could be because the markings helped them survive. For example, a tiger’s stripes camouflage it when hunting in a forest or grassland, making it easier to surprise and capture its prey.

However, researchers are still working out the details of what the chemicals are.

Scientists don’t always know the purpose of a pattern, or if there is one at all. The molecular processes involved are so simple that they could randomly generate a pattern.

For example, in my research team’s work examining plant pollen grains, we’ve seen a wide variety of patterns, including spikes, stripes, and more.

We don’t yet understand why one plant produces one pollen pattern and not another. Whatever the ultimate use of this and other patterns in nature, their variety, complexity, and order are astounding.

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