As people get older, the stem cells in their hair follicles become age-damaged and so your body can`t produce as many locks.
Eventually, this leaves many people with certain areas of their head without hair follicles.
Despite many people believing the opposite, hair follicles don`t continually produce hair; they work according to a cycle of dormant and active phases.
Researchers at Tokyo Medical and Dental University looked at the follicle stem cell growth cycles of mice.
Their study found that the age-related DNA damage kicks off a chain of protein-related events, which sees the Collagen 17A1 begins to break down is ultimately destructed.
The result of this is then transformed into `epidermal keratinocytes`, otherwise known as skin.
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After testing this research on humans, scientists found that people aged over 55 had less Collagen 17A1 and smaller follicles.
Emi Nishimura who led the research said: "We assume that ageing processes and mechanisms explain the human age-associated hair thinning and hair loss."
This research is likely to be used to help with the study of more general stem cell behaviour, reports Wired.co.uk.
And although this isn`t likely to be the only cause of hair loss, it does help a considerable amount in understand why it happens.
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