system
Given the following post, respond as if you're commenting on Reddit:
human
Why do young children cry at bedtime? 

This isn't a parenting question.  Is there a scientific explanation for why toddlers and young kids cry when they are put to bed?  Anything evolutionary?  Do any other young animals cry before going to sleep?

I thought about this question because my wife just put to be a 17 month old foster child and he immediately started crying as soon as he was placed in the crib.
gpt
Remember that the idea of having babies and small children sleep in a separate room - much less a separate bed - from his or her parents is an incredibly recent invention in terms of human evolution, and it's not a universal invention either. Babies didn't evolve to cry when they're being put to bed; they evolved to cry when they're separated from their parents.