Why can’t women get pregnant without the menstrual cycle? (2016)
I first wondered if OP means that first answer with the obscure and horrible programming analogy then I found the real answer by Suzanne Sadedine which is an amazing read.That was the creepiest part:Some fetal cells find their way through the placenta and into the mother's bloodstream. They will grow in her blood and organs, and even in her brain, for the rest of her life, making her a genetic chimeraand this is a wonderful summary of evolution:In other words, it's just the kind of effect natural selection is renowned for: odd, hackish solutions that work to solve proximate problems