From written record. We know for sure, since Old Egypt/bronze era, marriage was almost universal.
Heck, we even have tablets of workers that built the pyramid that were writing about how they think they made a mistake marrying their wife, as she is miserable and complains all the time, and suspicion of her cheating.
It is a story that could have been written today, but it was written 4800 years ago
There's a decent argument that marriage came about as a consequence of agriculture, where paternity suddenly mattered when it came to inheriting property. Of course, this predates writing, making it hard to definitively prove one way or another.
I'm not implying you don't find marriage in ancient times that resembles modern marriage. I'm pointing out the bold generalizations.
> We know for sure, since Old Egypt/bronze era, marriage was almost universal.
For sure almost. Earth's experienced a larger number and variety of cultures than some people give it credit for. Let's not make generalizations about human nature based on someone else's generalizations about human past. Noone owes a justification for acting the way they do. When you introduce justifications, you enter the realms of dogma.
Heck, we even have tablets of workers that built the pyramid that were writing about how they think they made a mistake marrying their wife, as she is miserable and complains all the time, and suspicion of her cheating.
It is a story that could have been written today, but it was written 4800 years ago