It's a weird American thing. People here even take out a mortgage to buy these ludicrously expensive engagement rings.
Spending too much on a diamond ring is common though
It's possible this changed between 09-13 because of the recession, but I'd bet it's very common now that the economy is doing really well.
This might not be a mortgage, in the sense of being a lifetime payment. But it's a (semi-)secured loan.
https://en.wikipedia.org/wiki/Signalling_theory#Sexual_selec...
FWIW, my wife has a $600 artificial diamond ring that she picked out at Walmart.com. It's one of her most prized possessions (not because of the cost, but because of what it symbolizes) and she frequently points out to people how inexpensive it was.
I distinctly remember her saying that if I were to pay 2 months salary for a ring it would be a sign that I was too dumb to marry. For that kind of money she'd rather have a new car.
Great attitude and totally on-point, responsible finances are one strong pillar under a relationship, if you blow through your cash on baubles you will eventually end up stressed.
We're quite happy with them.
Why not?
It's not just impractical; it's impossible to know enough of the variables to derive one from the other.
In practice "evolutionary" explanations are constantly used to make something intuitively plausible for which there is no evidence sound scientific and convincing.
Implies that <people> have no agency and run on instinct: see psychology, marketing theory
If you can use math to explain physics, physics to explain chemistry, chemistry to explain biology, biology to explain psychology, psychology to explain sociology, and sociology (plus history) to explain culture, then it would be fair to say you could use math to explain culture.
Of course, there's a lot of big gaps here, but the point is: trying to tie culture to biology is not without merit.
IMO, males and females both run on instinct through chaos crafted channels of superstition we call "culture". Like water running down a mountain in streams, it's not the channels which explain the waters movement downward (that's gravity), they just define the means through which it happens.