But on the plus side I've got a lot of great words to use in Scrabble now
It means they found an ancestor species to homonids in Europe. The title is wrong because it says Europe was a birthplace of mankind instead of a place an ancestor species of Humans evolved.
If I had to guess, I'd say it's being suggested that Graecopithecus is a species that modern humans are descended from. Late Miocene sounds like an era in the history of the world.
I'll take a stab
"Evolutionary Ancestors of Modern Humans Originate from Greece Instead of Africa"
Some people may read it as immediate ancestors. But I don't know how we can clarify that in a succinct manner.
"Potential Avolutionary Ancestors of Modern Humans Theorized outside of Africa"