Again, this is false and needs to be corrected. We see variance all the way from ~.65 to ~1 across entire cultures (let alone individuals), and this seems to be a trade off between estrogen and androgen.
The fact that women, pragmatically, tend not to have sexually "ideal" proportions, on average, in most societies isn't necessarily disproving of the idea that that ideal exists. Indeed, the relative rarity of individuals that match that ideal is what makes it, well, an
ideal, and ideals exists to judge other things against, not to be adhered to strictly. Indeed, the authors even mention that A) a low WHR does seem to correlate with longevity and fecundity, and B) less sexual attraction to men as a
tradeoff that women in societies with higher average WHR make, one that does not necessarily reduce their fitness levels if there are compensating advantages that make them more able to raise children in their particular environment. Indeed, the point of the paper seems to be that the male sexual ideal, while it is able to shift a little bit toward a higher WHR to match the reality of the female population around them, is not the be-all and end-all of what is evolutionarily fit in a given environment, which is not at all incompatible with what I said in the first place - namely, that a lower waist-to-hip ratio is what men seem to gravitate toward, sexually, in terms of what they prefer
in the abstract, unless there is a counterbalancing political and/or socioeconomic reality that makes such low WHR either impractical or a marker of an undesirable status or temperament within that society.
Couldn't you say the same things about current fitness levels? You seem to be suggesting that before it was just cultural influence, but now we have returned to our "natural" or "correct" preferences.
I suggest both are heavily culturally influenced.
How is that what I'm suggesting? My point is that non-heaviness is what is preferred, in terms of sexual attractiveness, by the vast majority of human societies, probably because overweight and obesity can be actively difficult (though, admittedly, not impossible) to achieve in the absence of modern dietary options, but that heaviness can be a marker of something deemed culturally more important or desirable in mate selection than pure appearance, especially since human culture can loop back around on itself and push such things to extremes, e.g. cultures where women are artificially fattened to almost cartoonish proportions in order to create the illusion of wealth and status. (Things that, incidentally, humans in our own society are often attracted to and oriented around, albeit with different markers.)
I agree that they exist, no question. Symmetry is the primary example. But these tend to be hugely overstated, as people tend to believe that beauty is more persistent and consistent than it actually is.
In other words, there are both cultural and genetic influences in what we find appealing, but people tend to overestimate the genetic or innate preferences significantly, and particularly tend to believe that our current culture is closer to the "correct" or "natural" ideal.
I don't necessarily think that the people that actually live in our modern culture are any closer to an ideal, but I definitely think the figures we depict in our media hover in the neighborhood of that partially, but not indefinitely malleable ideal. You may see fluctuations, which I never denied, but Beyonce looks a heck of a lot more like Grace Kelly looks a lot more like Setsuko Hara than any of them look (or looked) like average women of the societies they inhabit(ed).