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"It" being a biological basis for romantic behavior? We've survived this long without know how, or if, biology determines our current romantic behavior, I think we'll be okay. We're not going to go extinct because everyone is fucking robots.
Do we? Because I see no evidence of the opposite. Also, culture (and sociology for the matter) is biologically determined.
> no evidence of the opposite
There's plenty of evidence that romantic behavior is culturally determined. Just look at how much it has changed over the centuries even though, biologically, humans have hardly changed at all. There's also the wide variance between cultures geographically in which we're all biologically the same.