yaml is susceptible to things like the Norway problem: https://www.bram.us/2022/01/11/yaml-the-norway-problem/
There's also a lot of stuff that can go wrong with deserialisation that make it a tricky dependency for security purposes. I like how yaml looks and it's obviously much better than XML, but it had those potential problems
This article describes bottles found in children's graves, so maybe similar? I can't tell if they're the same bottles, but that would be one way for evidence to point to child bottles specifically. Good question though.
https://www.smithsonianmag.com/science-nature/bronze-age-baby-bottles-reveal-how-ancient-infants-were-fed-180973210/