"Our Brains Instantly Make Two Copies of Each Memory" (2017) https://www.pbs.org/wgbh/nova/article/our-brains-instantly-m... :
> We might be wrong. New research suggests that our brains make two copies of each memory in the moment they are formed. One is filed away in the hippocampus, the center of short-term memories, while the other is stored in cortex, where our long-term memories reside.
From https://www.psychologytoday.com/us/blog/the-athletes-way/201... :
> Surprisingly, the researchers found that long-term memories remain "silent" in the prefrontal cortex for about two weeks before maturing and becoming consolidated into permanent long-term memories.
ScholarlyArticle: "Engrams and circuits crucial for systems consolidation of a memory" (2017) https://www.science.org/doi/10.1126/science.aam6808
So that makes four (4) copies of each memory in the brain if you include the engram cells in the prefrontal cortex.
What is the survival advantage to redundant, resilient recall; why do brains with such traits survive and where and when in our evolutionary lineage did such complexity arise?