We need to get Donald Trump on this immediately.
It could be caused by the shape of his hairline, a slightly slapdash barber or simply a trick of the light.
But bloggers in America are convinced the ‘scar’ on Barack Obama’s head has a more sinister explanation.
Conspiracy theorists claim the line, running up over the president’s crown from behind his right ear, proves he has secretly had brain surgery.
They suggest it could be anything from a routine procedure to the work of extra-terrestrials, and have posted enhanced images of his head on Right-wing blogs as ‘evidence’.