When it comes to figuring out the world’s biggest mysteries, you need to consult the experts. That is why The Daily Beast contacted hair-restoration expert Dr. Sam Lam for his take on one of the biggest modern mysteries: Donald Trump’s hair.

A recent video clip made rounds all across the internet because it shed light on exactly what is going on with Donald Trump’s hair. In the clip, a gust of wind scatters the hairs on Trump’s scalp and reveals what appears to be a noticeable vertical scar across Trump’s scalp.

When asked about what this means in terms of hair-restoration procedures, Dr. Lam stated that the scar is likely to be the result of an outdated form of hair restoration known as scalp-reduction surgery. Scalp-reduction surgery was very popular around the 1990s but has since been abandoned in favor of much better options like hair transplantation.