system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: When and why did humans develop a sense of privacy around bathroom habits and sex?

I took my dog outside to poop and started wondering when humans stopped being cool with going to the bathroom in front of each other and having sex in front of each other. Animals do that stuff in front of anyone; they don't seem to have a sense of embarrassment about their bathroom habits or sexual practices. Why do we do these things in private and when did we start?
gpt
Sex is something that is societal, many cultures do not exhibit these behaviors.  Defecating on the other hand has evolutionary implications as it is not healthy to do it near others.  This is exhibited by many species.