Pigment comes from specialized cells and chemical compounds that absorb certain wavelengths of light and reflect others. In humans, nearly all visible pigment originates from a single molecule called melanin, produced by cells called melanocytes in the deepest layer of your skin. In plants, pigment comes from an entirely different set of compounds, including chlorophyll, carotenoids, and anthocyanins. Animals use many of the same pigment molecules as humans but often have additional cell types that let them shift color in seconds.
How Your Body Makes Melanin
Melanin production starts with an enzyme called tyrosinase. This enzyme converts the amino acid tyrosine into a compound called dopaquinone, which then goes through a cascade of chemical reactions to become melanin. All of this happens inside melanocytes, which sit in the bottom layer of your skin, in hair follicles, in the colored part of your eye, and in the retina.
Once melanin is packaged into tiny granules, melanocytes deliver it to the surrounding skin cells. A single melanocyte extends branch-like projections that touch up to 40 neighboring skin cells, forming what’s called an epidermal-melanin unit. The melanin granules travel along these branches and get absorbed by the surrounding cells, where they cluster above the nucleus like a tiny umbrella. That positioning is intentional: the melanin shields each cell’s DNA from ultraviolet radiation damage.
Two Types of Melanin, Two Color Palettes
Your body produces two main forms of melanin, and the balance between them determines your natural coloring. Eumelanin is a brown-to-black pigment responsible for dark hair, dark skin, and brown eyes. Pheomelanin is a red-to-yellow pigment that shows up in red hair, freckles, and lighter skin tones. The yellowish hue of pheomelanin comes from sulfur-containing amino acids (particularly cysteine) that get incorporated during its production.
Which type your melanocytes make depends largely on a receptor called MC1R. When this receptor is active, it triggers melanocytes to produce eumelanin. When it’s inactive or blocked, cells default to making pheomelanin instead. Common genetic variations in the MC1R gene reduce the receptor’s ability to stimulate eumelanin production. People who carry these variants tend to have red hair, fair skin, freckles, and greater sensitivity to sunlight.
There’s also a third type, neuromelanin, which is a dark pigment found only in certain brain regions. It forms as a byproduct of dopamine metabolism in specific neurons and plays no role in skin or hair color.
Why Skin Tones Vary Across the Globe
Human skin color evolved as a balancing act between two nutrients with opposite relationships to sunlight: vitamin D and folate. Ultraviolet radiation stimulates vitamin D production in your skin, but it also breaks down folate. Both are essential. The leading evolutionary model proposes that populations living near the equator, where UV exposure is intense year-round, developed darker pigmentation to protect their folate stores from degradation. Populations that migrated to higher latitudes, where UV levels are much lower, gradually lost pigmentation to allow enough sunlight through for adequate vitamin D synthesis.
This explains the broad geographic pattern: the darkest skin tones trace back to high-UV regions near the equator, and lighter skin tones are more common closer to the poles. It’s not a simple switch but a gradient shaped by tens of thousands of years of adaptation to local sunlight conditions.
Where Plant Color Comes From
Plants rely on a completely different chemistry. Four major pigment families create virtually all the color you see in the plant world.
- Chlorophyll is the primary photosynthetic pigment, absorbing red and blue light while reflecting green. It’s why leaves, stems, and unripe fruit appear green.
- Carotenoids produce yellow and orange hues. They’re abundant in carrots, sweet potatoes, mangoes, and autumn leaves (where they become visible as chlorophyll breaks down). Carotenoids also assist photosynthesis by capturing light energy and passing it to chlorophyll.
- Anthocyanins are responsible for red, purple, and blue pigmentation in blueberries, grapes, eggplant, cherries, red cabbage, and purple sweet potatoes.
- Betalains are a less common group that produces red and yellow pigments in beets, amaranth, prickly pear cactus, and certain fungi. They’re chemically unrelated to anthocyanins despite sometimes looking similar.
These pigments serve functions beyond appearance. Carotenoids and anthocyanins act as antioxidants, protecting plant cells from light damage, attracting pollinators, and signaling to animals that fruit is ripe.
How Animals Change Color
Many fish, amphibians, and reptiles can shift their skin color in seconds to hours using specialized pigment cells called chromatophores. Vertebrates have four main types: melanophores (containing dark melanin), erythrophores (red pigment), xanthophores (yellow pigment), and iridophores (reflective crystals that produce iridescent blues and silvers). These cells are often layered together in what’s called a dermal chromatophore unit, and the combined effect of expanding or contracting pigment within each layer produces a wide range of colors.
The process works by physically moving pigment granules inside the cell. When melanin granules spread outward along the cell’s branches, the skin darkens. When they pull back toward the cell’s center, the skin lightens. Hormones and neurotransmitters control this movement. In green anoles, for example, low levels of adrenaline activate receptors that darken the skin, while high levels activate a different set of receptors that override the first signal and lighten it. Cephalopods like octopuses and squid also use chromatophores, but their system is structurally and mechanistically different from what vertebrates use, relying on tiny muscles that physically stretch pigment-filled sacs open and closed.
Food Can Change Your Skin Color
Your diet can visibly alter your pigmentation, at least subtly. Carotenoids from fruits and vegetables accumulate in your skin and shift its undertone. In a controlled trial, young women who ate high-carotenoid fruits and vegetables (providing roughly 176,000 micrograms of beta-carotene per week) for four weeks developed measurably more yellow skin tones compared to those eating low-carotenoid produce. The change showed up in both sun-exposed and unexposed skin, and it correlated directly with blood levels of alpha-carotene and beta-carotene. Skin redness and lightness didn’t change, only yellowness. This is why people who eat very large amounts of carrots or sweet potatoes can develop a noticeable orange-yellow tint to their palms and soles, a harmless condition sometimes called carotenodermia.
When Pigment Production Goes Wrong
Several conditions disrupt normal melanin production or distribution. Vitiligo causes the immune system to attack melanocytes, leaving irregular white patches on the skin where pigment has been lost entirely. Albinism is a genetic condition in which the body produces little or no melanin, resulting in very light skin, hair, and eyes along with significant sensitivity to sunlight and vision problems.
On the other end of the spectrum, the body sometimes produces too much melanin. Sun exposure is the most common trigger, but pregnancy hormones, certain medications, and conditions like Addison’s disease can also darken the skin. Melasma, for instance, creates brown or gray-brown patches on the face and is particularly common during pregnancy. These conditions reflect the same underlying biology: melanocytes responding to signals (hormonal, immune, genetic) that either ramp up or shut down melanin production.