Excavations at the cave by Amgueddfa Cymru between 19 unearthed a total of 19 teeth, discovered found deep inside the cave.
These have been identified by experts at the Natural History Museum, London as belonging to an early form of Neanderthal.
Alongside them were stone tools and animal bones, some of which show signs of butchery - evidence that these were the food remains of these early Neanderthals.
Questions remain as to whether these humans were originally buried in graves within the cave.
Llanddewi Brefi is well known across Wales, the United Kingdom and throughout the world by people from all walks of life.The teeth have all been x-rayed and they show an interesting characteristic known as taurodontism - an enlarged pulp cavity to the teeth and shorter roots.