The findings confirm burials took place in Western Europe prior to the arrival of modern humans, the researchers report in the journal Proceedings of the National Academy of Sciences.
"This discovery not only confirms the existence of Neanderthal burials in Western Europe, but also reveals a relatively sophisticated cognitive capacity to produce them," said study lead author William Rendu a researcher at the Center for International Research in the Humanities and Social Sciences in New York City.
The center is a collaboration between France's National Center for Scientific Research and New York University.
The condition of well-preserved Neanderthal remains discovered in 1908 in southwestern France had led early 20th-century researchers to suggest the site marked a burial ground created by a predecessor to early modern humans.
Skeptics had maintained the discovery had been misinterpreted and the burial may not have been intentional.
Excavations of seven other caves in the area, completed in 2012, found more Neanderthal remains -- two children and one adult -- and geological analysis of the depression in which the remains were found suggests that it was not a natural feature of the cave floor, the researchers said.
"The relatively pristine nature of these 50,000-year-old remains implies that they were covered soon after death, strongly supporting our conclusion that Neanderthals in this part of Europe took steps to bury their dead," Rendu said. "While we cannot know if this practice was part of a ritual or merely pragmatic, the discovery reduces the behavioral distance between them and us."