Why is brown such a “default” colour in nature?


Brown seems to be such a default colour for things in nature and in day to life. Why is it so common for things to be or turn this colour in contrast to the vast array of other colours around?

In: Earth Science

Because “brown” is a result of mixing pretty much any two/three pigments (try it with red and green). That being said, it’s also because plants have usually two or three types of pigments and carotenoids are useful and abundant, and carotenoids range from yellows, to oranges and reds. For mammals that need to camouflage, it was useful to mimic the environments that are murky/shadowy especially since most mammals evolved from animals active in the mornings/evenings – hence ones producing melanin hit the jackpot and blended well with “murky” undefined colours such as varieties of brown.

I’m posting to see the answers here, this is a interesting question.

I’m think you’re asking two questions – why is the Earth (dirt, rocks, etc) brownish and why is life often brown-ish.

I think both come down to chemistry, the earth contains a lot of Iron which loves to react with oxygen and from reddish/brown compounds. If you look at the material breakdown of Earth many of core compounds are going to reddish/brownish. Probably no interesting answer there past “these types of compounds look brown”, you could get a quantum mechanical answer explaining the how, but the why is “that’s just the way things are”.

As far as life goes, you have all sorts of competing trends. Brown makes a good camouflaged since the earth is brown, so any animal that’s trying to blend in adapts to being brownish. Sometimes you have color that provides a purpose, trees and plants and animals that have colors are usually deliberately colored. It’s either providing a warning, the color is related to chemistry for example photosynthesis, or the creature is trying to attract mates. Finally not every animal blends in with the earth, sharks are lighter on the bottom because they’re being contrasted from below to blend in with the sky, green tree frogs are blending in with leaves etc.

Ultimately, I think the answer is boring. Brown is just a natural color for the chemistry of earth and without a specific purpose, things will tend to be brownish.

In Life in Colours from David Attenborough he explains that most mammals don’t have bright colors as they don’t have a wide spectrum of colours they can see. Colours in the animal kingdom is usually either for camouflage, to show dominance or to impress females.

Apart from that, earth and tree trunks can be brown but also many different colors. I’m not sure that there is more brown than green out there.

There are some correct answers here to *How* brown occurs in nature, put plainly there are chemical reasons, but I think *Why* it occurs more abstractly is interesting and worth thinking about.

Part of the *WHY* is that sight is a really complicated phenomenon that evolved over hundreds of millions of years. During that time frame plants and animals were establishing themselves world wide and paving the way for millions of species that would evolve from those early ancestors.

So in the same time frame that sight is born into the world, so are the basic building blocks of every species with absolutely no regard for color. Sight gave early adopters an advantage but its only after sight is relatively common that plants and animals start evolving ways to take advantage.

Therefore, color wasn’t significant to survival until several hundred million years into the evolutionary process. Following this logic we can say that other colors only appear in systems/organisms that evolved post-sight. This is why vibrant colors are often associated with complex behaviors like a specialized diet, mate selection and camouflage.

First things first, have you been checked for colorblindness?

How do we actually know it’s brown? Maybe that’s how the light reacts in our eyes but let’s say to a parrot it’s actually green or blue. 🤷🏻‍♂️

Humans can only see 3 colors and a mantis shrimp can see 8. So to a mantis shrimp humans are basically color blind. Your question why is everything brown is like a colorblind person asking why everything is grey.

Edit: mantis shrimp can see 12 colors

The ocean encompasses most of the earth = blue. Sky also not brown. The brown represents regeneration- either imminent or future so we can have regrowth. It’s not all doom and brown.

Because all those vast array of colors you see are actually the ability of the material to reflect a very specific wave length while also absorbing all other wave lengths. This is a difficult feat to accomplish and requires uniformity such as in crystals or very specific micro structures to pull off. For example the iridescent blue on butterfly wings of Morpho menelaus is the result of micro array of antennas exactly 2 μm apart producing it’s own refractive index to give it a vibrant blue color while absorbing all other wave lengths. However most things in nature are not uniform or structured and as a result will absorb and reflect a little of every wave length. This is equivalent to mixing a little of red, green and blue together (the color receivers in our eyes). So by default things lean towards chaos (the opposite of uniform and structure) which happen to be what we perceive as brown.

TLDR; Brown is the color of chaos.

If you’re talking about animals, that would mostly be due to the fact that mammals are the dominant land animals, and all mammals alive today had evolved after 100+ million years of being nocturnal to avoid the dinosaurs and pterosaurs.

Nocturnal animals have poor colour vision in exchange for night vision. So mammals lost most of the genes for developing vibrant colours.

Hence why birds fish and reptiles tend to be very colourful.

Life was much more vibrant before the KT extinction event (asteroid that killed the dinosaurs).