Grey hairs could be the scars left by our bodies’ war against cancer, a new study has found.
Recently published in Nature Cell Biology, the study looked into how the cells responsible for the pigments in our hair and skin ‘self-destruct’ when damaged, as part of our body’s efforts to protect us from cancer.
The scientists found that, under specific types of damage, these pigment-producing cells simply shut themselves down instead of continuing to divide.
That choice prevents faulty cells from spreading dangerous mutations – but over time, it also means fewer pigment-making cells remain, causing hair to turn grey.
Scientists have long explored ways to stop pigment cells from self-destructing in an attempt to prevent greying, but the new findings suggest your greys are a sign of an important anti-cancer defence.
“[This study] reframes hair greying and melanoma not as unrelated events, but as divergent outcomes of stem cell stress responses,” said Prof Emi Nishimura from the University of Tokyo, who led the study.
The Tokyo team made the discovery while studying melanocyte stem cells in mice – the cells that normally produce hair pigment. They found these melanocyte cells only sacrificed themselves when their DNA experienced a ‘double-strand break’, essentially a clean snap through both sides of the DNA helix.
But when the cells were exposed to other kinds of stress, such as ultraviolet light or carcinogens, they didn’t self-destruct. Instead, they survived and kept dividing, allowing mutations to build up and potentially laying the groundwork for cancer.
This two-track response – cells sacrificing themselves in some scenarios but clinging on in others – could help reveal why grey hair and skin cancers both become more frequent with age.
The researchers say that understanding – and eventually controlling – this response could open the door to new ways of eliminating high-risk cells before they become cancerous.
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