"A large adult tooth -- we can't say if it was from a male or female -- was found during excavations of soil we know to be between 550,000 and 580,000 years old, because we used different dating methods," paleoanthropologist Amelie Viallet told AFP.
"This is a major discovery because we have very few human fossils from this period in Europe," she said.
The tooth was found at one of the world's most important prehistoric sites in Tautavel, which has been excavated for about 50 years.
Volunteer Camille, 16, was working with another young archaeologist when she found the tooth.