It appears that a genetic mutation in a single individual in Europe 6,000 to 10,000 years ago led to the development of blue eyes, according to researchers at the University of Copenhagen.

"Originally, we all had brown eyes," said Hans Eiberg, associate professor in the Department of Cellular and Molecular Medicine at the university and lead author of the study. "But a genetic mutation affecting the OCA2 gene in our chromosomes resulted in the creation of a 'switch,' which literally turned off the ability to produce brown eyes."

It makes me question; If eye color mutations can start with only ONE individual, how many exotic eye colors have existed? Maybe someone with red eyes existed but died too young to reproduce. Maybe someone with yellow eyes will exist in the future. Who knows?

https://news.ku.dk/all_news/2008/blue-eyes/