Sideburns and temples go gray first because the pigment-producing cells in those follicles run out of steam before the ones elsewhere on your scalp. This isn’t random. Hair graying follows a remarkably consistent geographic pattern: it starts at the temples, moves to the crown, then spreads across the rest of the scalp, with the back of the head turning gray last. The reasons come down to differences in how hair follicles in each region handle cellular stress and maintain their supply of pigment stem cells.
How Hair Gets Its Color
Every hair follicle contains specialized pigment cells called melanocytes. During each growth cycle, these cells inject color into the developing hair strand. But melanocytes don’t last forever. They’re replenished by a pool of melanocyte stem cells that live in a specific zone of the follicle. When the stem cell pool shrinks or stops working, the follicle produces hair without pigment, and you see gray or white.
A 2023 study published in Nature revealed something surprising about how this system works. Melanocyte stem cells are mobile. They shuttle back and forth between different compartments of the hair follicle, shifting in and out of active states depending on chemical signals in their local environment. Over time, though, these stem cells get “stranded” in one compartment and stop responding to the signals that tell them to produce pigment. As more stem cells get stuck, fewer melanocytes are regenerated, and the hair loses color. This stem cell system fails earlier than virtually every other stem cell population in the body, which is why graying is one of the first visible signs of aging.
Why Temples and Sideburns Lead the Way
Not all hair follicles are created equal. Follicles in different body regions have different biological equipment for dealing with oxidative stress, the accumulation of damaging molecules that comes with normal cellular activity. Temple follicles appear to be less well-equipped for this fight than follicles in other areas.
One key difference involves a protective enzyme that melanocytes in some follicles produce and others don’t. Scalp hair follicles in general produce very low levels of this enzyme, which helps neutralize the byproducts of pigment production. But even within the scalp, there’s variation. Eyebrow and eyelash follicles, for comparison, produce much higher levels of this same enzyme and gray extremely slowly, even in people whose scalp hair has gone fully white. The follicles at the temples sit at the vulnerable end of this spectrum.
There may also be differences in the size of the stem cell reserve from one region to another. Follicles that start with a smaller pool of melanocyte stem cells will exhaust that supply sooner. Hormonal sensitivity varies across regions too. The temples are part of the same zone heavily influenced by androgens (the hormones also responsible for male-pattern hair loss), and this hormonal environment likely adds to the stress these follicles experience over time.
The Typical Timeline
Graying at the temples usually begins well before you notice it elsewhere. For people of European descent, the first gray hairs typically appear in the early 30s. For people of Asian descent, the late 30s is more common. For people of African descent, graying often starts in the 40s. A few gray hairs in your mid-to-late 20s is still considered normal. What counts as premature is going gray before 20, or being half-gray before 40.
The pattern after the temples is predictable. Gray spreads from the sideburns upward toward the crown, then fills in across the top and sides, reaching the back of the head last. Beard hair and body hair typically don’t go gray until well after the scalp has started. This sequence holds remarkably consistent across individuals, even though the age of onset varies widely.
How Much Is Genetic
You’ve probably heard that graying is genetic, and that’s true, but perhaps less than you’d expect. The gene most strongly linked to graying is IRF4, which plays a role in regulating the machinery that produces pigment. Carrying a specific variant of this gene roughly doubles the odds of going gray, and in younger people it can increase the probability of gray hair by about 15 percentage points. But this single gene explains less than 1% of the total variation in graying across the population.
When researchers built prediction models using age, sex, and 13 genetic markers together, genetics contributed to correctly predicting graying status in only about 9% of individuals. Age alone was far more powerful as a predictor. So while your genes set the rough timetable, they don’t explain why the temples go first. That geographic pattern is driven by the local biology of the follicles themselves, not by which gene variants you carry.
Why Some Regions Resist Graying
The flip side of the temple question is equally interesting: why do eyebrows and eyelashes stay dark so long? These follicles have much shorter growth cycles, around 100 to 150 days compared to several years for scalp hair. A shorter growth cycle means the pigment system has to work for less time per cycle, which may reduce cumulative stress on the melanocyte stem cells. On top of that, these follicles actively produce enzymes that protect against oxidative damage, something scalp follicles largely lack.
This regional variation in protective equipment is the core reason graying doesn’t happen uniformly. Your body isn’t losing pigment everywhere at once. It’s losing it first in the places where follicles are least protected and most metabolically stressed. The temples happen to be that place, which is why the first silver hairs almost always show up right where your sideburns meet your hairline.