Born in
Tréménoc in 1936, Le Rhun grew up in a peasant family from
Bigouden. After secondary school, he studied geography at the
University of Lyon, where he had his thesis directed by
Maurice Le Lannou. After his graduation in 1962, he completed his
military service before returning to
Brittany. After serving as a secondary school geography teacher, he joined the
University of Nantes as an assistant professor in 1968. He became a full professor after writing a thesis titled ''L'aviculture intensive en Bretagne
. As a committed geographer, he dedicated much of his time to cultural preservation in Brittany, such as preserving bocage bridges, the protection of the , and opposing the . This organization later became , which contributed to analyses and surveys on public opinion and emphasizing the importance of a democratic debate on regional borders. In 1973, he published an article in Le Monde'', which covered the way the
May 68 protests awakened many minority linguistic groups in France. In 2000, Le Rhun was awarded the
Order of the Ermine for his engagement with the Breton culture and identity. Le Rhun died in
Pont-l'Abbé on 12 October 2025. ==Works==