It's a useful mnemonic but also a misleading one when compared to the Biblical account:
- "Mitochondrial Eve" was not the only woman alive at the time, just the only one who still has surviving descendants
- She did not live at the same time as Y-chromosomal Adam, unless by sheer coincidence. They likely never met even if they were the same age.
- Both of these are titles, not people. As family lines die out, they both forward in time to new individuals. 1,000 years ago we probably had a different Adam and Eve who lived earlier in time.
- There's a book "Seven Daughters of Eve" which follows the splitting of haploid groups from Mitochondrial Eve, but you can pick any arbitrary number. They were not literally her daughters, and you could just as easily split further to get 8 or 9 or 100 of them.
It's neat stuff, but it's more "This is how math works" than "This is a historical account of a real-life woman and man who never met but their favorite color was blue."
https://xkcd.com/1545/ One day I too will either be the ancestor of all living humans, or none of them! I guess I'd be Y-chromosomal Eve lol