The Bruniquel cave, in southwest France, is believed to be a Neanderthal dwelling 100,000 years before humans in Europe. Stalagmites in the cave may have been arranged as walls, and possibly as a fireplace. Charred bone found in the walls date to 175,000 years ago.

This cave is apparently fairly deep. Cross reference this with deep cave fires and asphyxiation research.

• Article: https://www.theguardian.com/science/2016/may/25/neanderthals-built-mysterious-cave-structures-175000-years-ago
• Related journal article: http://nature.com/articles/doi:10.1038/nature18291

Is it possible that such a place was used as a memory palace? Being secluded away and the play of fire inside would certainly fit some of Lynne Kelly's criteria from Knowledge and Power in Prehistoric Societies. More evidence would be needed however.

<small><cite class='h-cite via'>ᔥ <span class='p-author h-card'>LynneKelly </span> in "Ancient Australian Aboriginal Memory Tool Superior to ‘Memory Palace’ Learning" - Neuroscience, Psychology, and Health - Art of Memory Forum (<time class='dt-published'>10/19/2021 09:26:03</time>)</cite></small>

I don’t think the methods were worked out as much as evolved with the human brain. I suspect those who started using mnemonics survived and bred better than those who didn’t.

I have been pointed to this discovery of a Neanderthal cave many times, with archaeologists suggesting to me that it points to Neanderthal use of a memory palace. It would need more evidence to be convincing, but that would go back a very long time.

Interesting article to read and build evidence as Kelly suggests.

All these are forms of art that prove some sophistication because these marks were not left randomly and there surely was a purpose and/or meaning behind them.