The oldest color produced by a living organism and preserved in the geological record is bright pink. In 2018, researchers crushed 1.1-billion-year-old marine shales from Mauritania and extracted intact porphyrins, the molecular remnants of ancient chlorophyll, that ranged from blood red in concentrated form to a vivid pink when diluted. But what counts as the “oldest color” depends on whether you mean pigments made by life or colors that existed in nature, and the distinction takes you from billion-year-old bacteria all the way back to the earliest minerals on Earth.
The Billion-Year-Old Pink
The pink pigments came from rocks in the Taoudeni Basin of Mauritania, a geological formation that captured sediments from an ancient ocean floor. When scientists ground the rock into powder and analyzed the organic molecules trapped inside, they found porphyrins, the ring-shaped molecular skeletons that remain after chlorophyll breaks down over geological time. These particular porphyrins were about 1.1 billion years old, making them roughly 600 million years older than any previously discovered biological pigments.1Proceedings of the National Academy of Sciences. 1.1-billion-year-old porphyrins establish a marine ecosystem dominated by bacterial primary producers The discovery was remarkable not just for the age of the molecules but for how much information they still carried about the organisms that produced them.
The nitrogen isotope signatures in those porphyrins pointed directly to cyanobacteria as the dominant photosynthesizers in those ancient seas. The isotopic values were heavier than what shows up in younger marine sediments, and the pattern was consistent with a world where tiny bacterial cells, not larger algae, ruled the sunlit ocean surface.1Proceedings of the National Academy of Sciences. 1.1-billion-year-old porphyrins establish a marine ecosystem dominated by bacterial primary producers Alongside the porphyrins, researchers found fossil carotenoid signatures from green and purple sulfur bacteria, organisms that photosynthesize using different wavelengths of light than cyanobacteria do. The ocean 1.1 billion years ago was a microbial world painted in shades we would find alien today.
What the Pink Pigments Reveal About Ancient Oceans
The discovery did more than establish a record-setting pigment. It helped settle a long-running question about when the oceans shifted from being dominated by bacteria to being run by algae. In a bacterial-dominated ocean, the base of the food web consists of tiny cells with relatively little energy to offer anything that eats them. That has cascading consequences for the entire ecosystem, including why complex animal life took so long to evolve.
Molecular fossil evidence from younger rocks shows that the transition from cyanobacterial to algal dominance in the open ocean happened between about 659 and 645 million years ago, during a warm period sandwiched between two global glaciations.2Emerging Topics in Life Sciences. The transition from a cyanobacterial to algal world and the emergence of animals That means the pink porphyrins from 1.1 billion years ago sat squarely in the cyanobacterial era, roughly 400 million years before the algal takeover. The color of the oldest biological pigment, then, is also a timestamp for a particular kind of ocean, one that could not have supported the large, energy-hungry animals that would eventually appear.
Was Earth Purple Before It Was Green
The pink porphyrins are the oldest biological pigments we can physically hold, but some researchers think even older colors once dominated the planet. The “Purple Earth” hypothesis proposes that before photosynthesis evolved using chlorophyll, the earliest light-harvesting organisms relied on a simpler molecule called retinal. Retinal is the pigment used by bacteriorhodopsin, a protein originally discovered in salt-loving archaea, and it absorbs green light while reflecting purple and red wavelengths.3International Journal of Astrobiology. Early evolution of purple retinal pigments on Earth and implications for exoplanet biosignatures
If retinal-based organisms blanketed the early Earth before chlorophyll-based photosynthesis took over, the planet’s surface may have had a distinctly purple tint from space. The evidence for this is indirect: retinal pigments are widespread across archaea and bacteria today, and the genetic machinery for producing them appears to be very ancient. The hypothesis remains speculative, but it raises the possibility that the “oldest color” in a biological sense was not pink or green but purple, predating even the cyanobacteria whose chlorophyll fossils we have found.
Colors That Predate Life Entirely
If you step away from biological pigments, color on Earth goes back much further than any living organism. Minerals produce color through their crystal structure and the metal ions trapped within them. Iron oxides create reds, oranges, and yellows. Banded iron formations, some of which are more than 3 billion years old, display striking rusty reds from oxidized iron and dark grays from reduced iron. These colors were not produced by life; they are a consequence of chemistry and the way iron interacts with oxygen in water.
Even the sky had a different color. During the Archean eon, roughly 2.5 to 4 billion years ago, the atmosphere contained no free oxygen and was rich in methane and other gases. Under certain conditions, photochemical reactions in this atmosphere would have produced an organic haze similar to what we see on Saturn’s moon Titan today. Simulations show that a thick enough haze could have cooled Earth’s surface by around 20 degrees and cut surface UV radiation by about 97 percent, potentially allowing organisms to survive on land far earlier than expected.4PubMed Central. The Pale Orange Dot: The Spectrum and Habitability of Hazy Archean Earth That haze would have given the sky a pale orange tint, nothing like the blue we are used to. So if you define “oldest color” as the color of Earth’s environment rather than a pigment made by something alive, pale orange is a strong contender, stretching back billions of years before any biological pigment entered the record.
Sunscreen Before Sunscreen
One of the earliest reasons organisms developed pigments was not to be colorful but to survive. Ultraviolet radiation in the Archean was intense, and early life needed chemical shields. Cyanobacteria evolved a pigment called scytonemin, a yellowish-brown compound sequestered in their outer sheaths that absorbs UV radiation before it can damage the cells underneath. Genetic analysis suggests the biosynthetic machinery for scytonemin is distributed across several cyanobacterial lineages and has an ancient evolutionary origin, consistent with UV protection being one of the first problems pigments evolved to solve.5PubMed Central. Organization, evolution, and expression analysis of the biosynthetic gene cluster for scytonemin, a cyanobacterial UV-absorbing pigment
When plants eventually moved from water to land, they faced the same UV problem and developed their own pigment-based solutions. Flavonoids, the class of molecules responsible for many of the yellows, reds, and purples in flowers and fruits today, appear to have been multifunctional from the start. Beyond filtering UV, they helped early land plants manage nutrient uptake by promoting symbiosis with root fungi and defended against new biotic threats in the terrestrial environment.6PubMed Central. Beyond Photoprotection: The Multifarious Roles of Flavonoids in Plant Terrestrialization The familiar colors of a flower garden trace their ancestry back to the survival chemistry of the first organisms to crawl out of the water.
Reading Color from Fossils
Ancient pigments like the Taoudeni porphyrins are molecular fossils, chemicals preserved inside rock. But there is another way color survives deep time: through physical structures. Some colors in nature come not from pigment molecules but from the way microscopic structures in a surface interact with light. These are called structural colors, and they produce the iridescent sheen on beetle shells and butterfly wings.
Researchers have found that the nanoscale architecture responsible for structural color can survive fossilization remarkably well. In 47-million-year-old moth fossils, for instance, the internal layered structures within wing scales, the structures that control color in living moths, were still intact and varied according to the original color and position on the wing.7PLOS Biology. Fossilized Biophotonic Nanostructures Reveal the Original Colors of 47-Million-Year-Old Moths Fossil beetles tell a similar story: metallic structural colors generated by multi-layered reflectors in the cuticle can persist, though how faithfully they survive depends on how well the surrounding cuticular structures are preserved.8PubMed Central. The original colours of fossil beetles
Pigment-based color can also leave physical traces. In fossil feathers, tiny granules called melanosomes, the cellular structures that contain melanin, preserve their shape over tens of millions of years. The discovery that fossil feathers retain melanosomes opened up the possibility of reconstructing color patterns in extinct birds and even dinosaurs.9PubMed Central. The colour of fossil feathers In one striking case, researchers mapped the melanosome distribution across the entire body of a Late Jurassic feathered dinosaur and determined that it had a gray-and-dark body, a reddish-brown crown, rufous facial speckles, and white limb feathers with black tips.10PubMed. Plumage color patterns of an extinct dinosaur That kind of detail from a creature that lived over 150 million years ago is extraordinary, and it comes entirely from the physical survival of pigment-carrying structures.
Why Fossil Colors Are Not Always What They Seem
There is a catch to reading ancient colors. The chemical and physical processes that occur after an organism dies, collectively called diagenesis, can alter pigments in misleading ways. Eumelanin, the most common dark pigment in animals, begins to chemically degrade at certain temperatures and burial depths, but the granules that contained it do not always change shape to match. That disconnect is a real problem for paleontologists: a melanosome can look perfectly preserved under an electron microscope yet contain degraded or absent melanin inside, leading to overconfidence about original coloration.11Organic Geochemistry. Impact of diagenesis and maturation on the survival of eumelanin in the fossil record
The billion-year-old porphyrins from Mauritania are a case where the chemistry survived intact enough to yield useful information, but they are exceptional. Most biological pigments degrade long before reaching such ages. Carotenoids, for example, are relatively fragile compared to the porphyrin ring structure, which is one reason why chlorophyll derivatives dominate the record of very ancient biological color. The record is biased toward molecules that happen to be tough, and whatever other colors organisms were producing a billion years ago are likely lost to us.
The Oldest Pigments Humans Used
When the question shifts from “oldest color in nature” to “oldest color used by people,” the answer is ochre. Ochre is a catch-all term for iron-oxide-rich earth pigments that range from deep red to bright yellow depending on the mineral composition. It is among the earliest materials deliberately collected, processed, and applied by humans.
At Blombos Cave in South Africa, excavations uncovered what appears to be a 100,000-year-old ochre-processing workshop. Two abalone shells served as mixing containers for a liquefied ochre-rich mixture, alongside bone spatulas, charcoal, grindstones, and hammerstones that formed a composite production toolkit.12PubMed. A 100,000-year-old ochre-processing workshop at Blombos Cave, South Africa That is not a casual smear of red mud; it represents deliberate, multi-step processing of a mineral for a specific purpose, whether decorative, symbolic, or practical.
More recent work at the same site has shown that ochre played an even broader role than previously appreciated. Some ochre pieces were intentionally shaped and used as lithic retouchers, tools for pressure-flaking stone implements. These pieces show clear use-wear patterns confirming they were used for stone toolmaking and then rejuvenated to maintain their function.13PubMed Central. Unveiling the multifunctional use of ochre in the Middle Stone Age: Specialized ochre retouchers from Blombos Cave Ochre, in other words, was not purely a pigment. It was also a material technology. The red and yellow colors we associate with the earliest human art are inseparable from the practical toolkit of Middle Stone Age life.
The First Artificial Color
For most of human history, all pigments came from the ground, from plants, or from animal products. The first known synthetic pigment breaks that pattern: Egyptian blue, a calcium copper silicate with the chemical formula CaCuSi₄O₁₀. It was produced in Egypt by at least the third millennium BCE, making it roughly 5,000 years old. The manufacturing process involved heating a mixture of silica sand, a copper-containing mineral, calcium carbonate (limestone), and a flux at high temperatures, a process complex enough that it required real craft knowledge.14Eurasian Chemico-Technological Journal. Ancient Egyptian Blue (CaCuSi4O10) Pigment by Modern Solution Combustion Synthesis Method
Egyptian blue is interesting for reasons beyond its age. The pigment emits near-infrared fluorescence when illuminated, a property that has made it useful to modern conservators trying to identify traces of the pigment on ancient surfaces that no longer appear blue to the naked eye. It also marks a conceptual leap in the history of color: from finding colored materials in nature to engineering them from raw ingredients. The vivid blue it produced was not available from any naturally occurring mineral in Egypt, so creating it was a way of making a color that the local landscape could not provide.
How Color Might Betray Life on Other Worlds
The connection between ancient pigments and life has a forward-looking application in the search for biology beyond Earth. On our planet, land vegetation reflects near-infrared light very strongly, a feature called the vegetation red edge. Astronomers have proposed using this spectral signature as a biosignature, a way to detect surface vegetation on exoplanets by looking at the light they reflect.15PubMed. The Vegetation Red Edge Biosignature Through Time on Earth and Exoplanets
The Purple Earth hypothesis adds a twist. If retinal-based organisms once dominated our own planet, then a purple surface reflectance signature might be a valid biosignature for worlds in a different stage of biological evolution.3International Journal of Astrobiology. Early evolution of purple retinal pigments on Earth and implications for exoplanet biosignatures In other words, finding an exoplanet that looks purple rather than green would not rule out life; it might suggest life in an early, pre-photosynthetic phase. The oldest colors on Earth are becoming a template for interpreting colors on planets we have never visited. What we learn from billion-year-old rocks in Mauritania and speculative models of the Archean sky shapes what astronomers will look for when the next generation of telescopes turns toward distant worlds.