Why does this lie keep getting perpetuated?
Sumer and Egypt both had Man, Woman and Child as the original trinity and offering a dowry for a wife is as old as civilization.
There will never be a civilization without a family unit and a family unit will not work without laws.
Humans existed long before those civilizations.
Look at this very topic...marriage is shrinking in the US. And Out-Of-Wedlock births are SOURING in Europe right now...the trend is against marriage in modern, developed societies. There will always be families...but they aren't always going to look like what we think of them right now. Just as they looked different in the past, (I'm not an expert on Egypt for instance, but I'd be willing to bet that "marriage" for them was more similar to what we would consider "bondage" now....with a woman as essential property owned by a man. If not there, than it was definitely like that elsewhere). It's interesting that you brought up dowry's.....How long are you expecting those to live on? All it takes is a rise in consciousness from women...and that dies out, arranged marriage goes with it. 50's style "homemaker" soon devolves after. Then it's marry but divorce. So on and so fourth....
Regardless, it's certainly not a biological imperative. We don't have to find a spouse or risk an untimely death. It's just the way we've collectively chosen to organize for most of our (written) history. I personally think that any cultural touchstone, regardless of how old or sacred, is at risk if it doesn't serve an innate, biological need.
It's hard to speak on future human "civilization" because globalization has changed everything. I can barely wrap my head around how different the world is. What I do know is that society isn't going to crumble just because people have given up on 2.5 kids and a white picket fence.