eli5: Why do most people have no memories from before age 4 or 5 years old?
In: 4721
Since most replies here are either based on “quick googling” or are talking about language and other tangentially related things:
The term for this is [infantile amnesia](https://www.jneurosci.org/content/37/24/5783) and it’s observed in different species, including humans, mice, and rats. This suggests that this type of unstable early-life memory is not exclusively related to language or self-identity, although these things may play a part.
Evidence from animal models shows that infantile memories [are persistent, but become rapidly inaccessible](https://www.sciencedirect.com/science/article/pii/S096098221830695X?via%3Dihub), unlike adult memories. This strongly indicates that the information content is retained even after the animals can no longer recall the memories naturally. As far as I’m aware we do not know whether this is the case in humans as well.
There are many unknowns about the mechanism for this, although the two papers I liked describe and test some potential mechanisms: the section called “Infantile amnesia and explanatory hypotheses proposed to date” in the first one. The second paper is an experimental one, so it is much more technical and might be hard to understand without a lot of background knowledge.
This is not exactly an ELI5 answer, but I feel like the top comments here either don’t answer the question at all or do so in an extremely superficial way (IMO beyond what you’d expect for this sub).
It’s not exactly my research area but if you have any specific questions, let me know!
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