I always hear how we’re so susceptible to obesity and other problems from high calorie and high fat diets because our bodies have evolved to store that energy due to the difficulty in finding food for most of human existence.
Since skinniness is attractive and thus a sexual asset, I would expect people who can eat whatever they want and not get fat to be having more kids than overweight people who are not attractive by modern standards. At some point, I’d expect those lucky genes to be passed down so that we’ll see more people able to eat whatever they want and not gain weight and not drop dead from heart attacks. Is there any evidence this is actually happening? I know it’s only been a short time in human history, relatively speaking.
Not as far as I know. It’s only been a couple of generations that being overweight has been prevalent, and that’s mainly in developed countries. Also, I doubt there’s any evidence that thin people even in these societies have more children than overweight people.
Heart attacks and other health problems that occur after people have had most of their children aren’t going to have much of a selective effect anyway.
Evolution in large populations takes a lot of time.
There are many flaws in your notion. For starters, the kind of obesity that discourages breeding (by being universally distasteful) tends to lag breeding age: most younger people are not getting fat enough quickly enough to be selected out.
But more importantly, as a social species, our social interactions take precedence over our figurative plumage, we tend to respond to cues well beyond what a person looks like and can become physically intimate with someone we might not have been initially attracted to (inner beauty and all that nonsense).
And never underestimate the power of horniness. People will schtup almost anyone at almost the drop of a hat when they get so worked up. Even if you were looking at a realistic timeframe for evolution, I just do not think the relevant environmental pressures are significant enough to have a meaningful effect.
I’m not suggesting fat people never have sex, just that thin people are considered more attractive and in a natural selection sense they have an advantage. They could be thin because they eat healthy though, and I do concede that. Of course the ability to consistently eat healthy and stay thin is probably genetic to some significant degree.
Humans are taller now than they were back in the 1700’s. I remember reading part of that is due to more vitamins and healthier living but I’m pretty sure I read part of that was genetics too. Don’t have a cite right now but i’ll see if i can find one.
The main driver here is not that skinny people are more sexually attractive - that’s a cultural artifact, it’s universally true even today, and in any case fashions in body shape can change in what is, in evolutionary terms, the blink of an eye. There is no reason to think that a preference for slimness will persist long enough to have an evolutionary impact.
A slightly bigger factor is that, as long as we continue to have high-fat, high-calorie diets our health will be adversely affected, and of course the more susceptible you are to damage from such a diet, the sooner you will die, and the more likely that even if not dead you will be too sick to procreate successefully. Thus those who are less affected by high-fat high-calorie diets will tend to have more offspring. But of course the high-fat high-calorie diet would have to continue for a long, long time to have any measurable impact on human evolution.
Since when? More fleshy (not necessarily fat but heavier set) people were considered attractive at various points in history.
Ever hear of the term “Rubenesque”? Rubens was known for his predilection for “full figured” women. He wasn’t exactly alone.
I really doubt there’s any evidence this is genetic. At all.
The 1700s is only a few generations ago, and a genetic change across all humanity would be a questionable hypothesis. Even limited to developed countries, it’s only a few generations with no selection pressure on height. For countries like the US? Even less selection pressure, since there’s considerable mixing from immigrant populations.
I’d love to see that cite, because this sounds a lot like pseudo-science at first glance. A genetic change that is prevalent across all humanity would take several more generations than that.
Worse, we have direct evidence it’s not genetic. Take the difference in height between South and North Koreans. South Koreans are almost a full foot taller. That’s not genetic (not in 1 or 2 generations anyway). That’s entirely better nutrition and healthcare.
Great Antibob: Since recently. I acknowledge fat people used to be considered attractive in/around Elizabethan times, though that was because it was a sign of wealth, not necessarily physical attraction. The degree of skinny that’s considered ‘attractive’ varies over time (looking at Marilyn Monroe today she was a fat porker who would only be able to get a job modelling plus-size women’s clothes). But I have a very hard time believing obese people were ever sexually attractive. Sign of wealth yes. Beauty? No. I just don’t see that being culturally subjective. I’ve never read anything that implied Henry VIII was considered more handsome/attractive when he became orca fat.
I found a lot of articles that talk about evolution and human height but they all seem to agree the recent change from the 1800’s on is solely due to improved diet. I guess the fact that they all talk about human evolution is what made me remember it that way.
One of the key things about human populations is that almost everybody gets married and has kids. We aren’t like some animals where the weaker males have no offspring, and there is a significant mechanism to prefer the dominant male’s genes. Fat, thin, poor rich, it makes very little difference, all have kids, and in roughly the same numbers. Maybe beautiful people may tend to marry one another, and leave the ugly ones to marry one another, which would suggest that there are pressures to divide the populace into beautiful and ugly, but there is no pressure that stops fat ugly people finding other fat ugly people to marry and create fat ugly kids. If physical beauty is the only determinant (which history shows it really isn’t, for all but the most shallow.)
There are inverse effects, as has been noted, richer societies seem to have fewer kids, to the point where we see actual negative population growth. Poor people seem to reproduce more. And so it goes.
In general, fidelity in human marriage tends to mostly nullify the idea of the alpha male spreading his genes far and wide to the exclusion of the weaker epsilon males, or even more beautiful people versus the ugly. There are of course infidelities, and more jokes about milkmen that one likes to remember.
Whilst that’s the message we’re been fed (ha!), I suspect the truth is somewhat different.
Since the late 70s, we’ve all been receiving the ‘fat is bad’ message, thanks to the Seven Countries study which demonstrated an association between fat in diet and heart disease (and as any statistics student knows, correlation does not prove causation). So we’ve eaten our ‘lite’ products and moved to a high carb/low fat eating paradigm (think about the ‘healthy eating pyramid’ which was designed by a junoir government employee with no nutritional science training). The result? Increased obesity.
Wrong. There’s good reason to believe that about 80% of women throughout human history have reproduced, while only about 40% of men have. The phenomenon of everyone pairing off equally and having a few kids is an artifact of safe, stable, prosperous societies that favored beta male providers–something we’re now trending back away from.
To the OP, one could counter that in our society of richly abundant calories, being thin is associated with higher impulse control and more future time orientation, two characteristics which, with the ready availability of contraception, and the fact that we seek sex mainly for pleasure rather than procreation,are associated with having fewer offspring, not more.
Evolution works by raising the probability of survival at least up to reproductive age. If everyone lives long enough to reproduce, no matter how fat they are, the mortality of the condition will not work its way out of the gene pool.
Given the OP was talking about safe prosperous stable Western societies that indulge in massive overeating and the attendant obesity I think it was close to correct.
Clearly prior to these times there is a lot of pressure that favours the alpha male. Harems are not exactly unknown. Tribal societies distinctly tended to disfavour the epsilons.
If obesity continues to be very prevalent in modern societies, I would think that cultural preferences would shift more rapidly than natural selection would have any effect.
Morbid obesity wasn’t possible for the vast majority of people until recently anyway. There’s no selection pressure against them, because it was an uncommon situation unless you had a huge amount of resources, i.e. limited to the very wealthy. And even then, such levels of obesity usually don’t manifest earlier in life, i.e. they happen after you’ve had a chance to breed.
Trying to make a natural selection argument about obesity doesn’t make sense. It’s only been possible for large numbers of people in the last century. And even now, it’s possible in a widespread sense only in developed countries, i.e. where there’s plenty of food.
Also, it’s basically pseudo-science to suggest such a subjective criteria like attraction to obesity can’t exist, though you could make the argument it is possible. After all, the ancient Maya believed elongated heads were attractive. And most people have heard about Chinese foot binding.
What we find attractive is not objective at all. It’s largely shaped by our culture and our history. One only has to look at sexual totems across thousands of years of human history to see that what we found attractive in women covers most of the spectrum of possible physical attributes.
You have assumed that the limiting factor on fertility is sexual attractiveness. How is that supposed to work? Do you imagine that there is a substantial risk that fat people will die virgin, completely unable to attract a sexual partner? Or do you imagine that of those people who do find sexual partners, those who are more attractive fuck so much more often and carelessly that willy nilly they end up having more children?
Either one seems iffy. The limiting factors on fertility seem very unlikely, in the modern society, to have any relationship to the limiting factors on getting laid. Thing is, most people get laid about 1000 times more often than they have children. So factors can boost or reduce the frequency of coition by a whole heck of a lot before they necessarily have any effect at all on the frequency of childbearing.
