... it's a solar panel for not-getting prostate cancer.
A receding hairline can be a good thing, according to US scientists, who say men who go bald by 30 appear to be less likely to develop prostate cancer.
Researchers at the University of Washington School of Medicine studied 2,000 men aged between 40 and 47.
They were able to link high levels of the male hormone testosterone in those who lose their hair earlier with a lower risk of tumours.
The journal article, in this month's issue of Cancer Epidemiology is here and contains this pleasant sentence:
Given the prevalence of hair loss with increasing age and evidence that eunuchs will only demonstrate baldness if castrated after age 25 or if supplemented with testosterone, it may be important to capture hair patterning at critical periods of time if its utility as a risk factor is to be adequately tested.