A reader asks:
Do you know of any studies investigating whether there is a correlation between a child's physical resemblance of one parent and that child's similarity in personality to that same parent? e.g. Al looks much more like Dad and has his laid back personality, while Al's brother Bob looks much more like Mom and has her lively personality.
Assuming that Bob really is Dad's son, of course ...
I don't know, but this is a good question because it could help get at an idea that has been lingering for a long time -- are differences in looks associated with differences in behavior? If so, why?
Greg Cochran has a strong aversion to Darwin's theory of sexual selection (not because it's never true -- it is in some cases -- but because it gives too easy an out for explaining physical differences: "Somebody must have thought it looked purty.") He suspects, for example, that fair hair and fair skin were less selected for in themselves than that they were by-products of something else that was being selected for in Europe.
Looking at siblings who look different, especially fraternal twins, might provide some evidence on this subject.
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27 comments:
"Assuming that Brian really is Dad's son, of course ..."
lol
right
I heard on House that this stuff happens all the time!
so why not
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Steve quotes greg cochran:
He suspects, for example, that fair hair and fair skin were less selected for in themselves than that they were by-products of something else that was being selected for in Europe.
I have always thought the same thing but I cant figure out for the life of me, what it was that fair skin, warm-colored hair and cool-colored eyes were proxies for. Its probably something incredibly banal like a digestive enzyme.
Perhaps the genetic bio-chemistry of this trait meant that the people who had it also tended to have what we now call "European" coloring. Since they survived better than those without it, the descendants evolved a psychological preference for that coloring, as an index of a good mate.
Sexual selection must be critical in determining whose genes get propagated into the next generation. And of course, sexual drives are stimulated by sexual appearance.
But nature is not interested in "sexy looks" per se, it is interested in performance ie survival ability. Unless the looks are some sort of camoflage to throw off predators or plumage to attract the attention of mate. Is blonde hair just female plumage?
Psychologically appealing appearance and physiologically enduring performance get linked as nature inscribes a hard-wired preference for certain appearances that invariably linked to key performances.
Of course there are plenty of traits where aesthetic sexual appearance and utilitarian survival performance are organically identified. Big muscles are an obvious example.
Those physical features that commonly stimulate attraction and sexual desire are merely expressions of hormone levels and therefore proxy indicators of fertility.
Most men have an attraction to women with shapely breasts and behind, plus large eyes and a tapered jaw - all of which are expressions of high levels of oestrogen and progesterone.
Most women have a preference for men with a square jaw, broad shoulder, deep voice etc which are expressions of high levels of testosterone.
However, its worth noting women are less motivated by sexual attraction when it comes to choosing a partner than are men. Women tend to be more attracted to status and other factors. This is why the stereotype of what makes a woman attractive is relatively unchanged through time while the stereotype of an attractive man has changed markedly since the triumph of feminism. Think of hairy-chested alpha male Burt Reynolds vs. effete girly men like Johnny Depp today. In a society where women increasingly want men who do as they're told, the last thing they want is a man's man as a partner.
At no time or place in Europe has natural blonde (or red) hair been in a majority.
If it was a by-product of something else that was being strongly selected for in Europe why did those without it manage to survive eh?
but I cant figure out for the life of me, what it was that fair skin, warm-colored hair and cool-colored eyes were proxies for.
Look at the Russian experiment with silver foxes where they bred the tamest ones for 30 generations. They turned wild animals into domesticated, friendly puppy-like creatures, with the unintended consequence of lightening their pigmentation.
"At no time or place in Europe has natural blonde (or red) hair been in a majority."
Not true, the fierce Germanians durng roman times were known to have only light hair.
I haven't kept up on this issue, but I know there are at least two studies that found no relationship between physical resemblance and personality resemblance in twins:
Matheny, A. P. Jr. et al. (1976). Relations Between Twins' Similarity of Appearance and Behavioral Similarity: Testing an Assumption, Behavior Genetics 6:343-351; Plomin, R. et al. (1976). Resemblance in Appearance and the Equal Environments Assumption in Twin Studies of Personality Traits. Behavior Genetics, 6:43-52.
I am the oldest of two and have my mom's eyes but am otherwise a chip off the old block. I ended up with my mom's strong aesthetic sense and depressive tendencies. I got my dad's high T and square jaw and chin, broad shoulders, etc. We both have a great sense of humor and volcanic tempers.
My younger sister, like my mom, is petite with her ovular face, but got my dad's nose and upper facial structure. She is the mental/emotional polar opposite of my mom, and is stubborn and optimistic like my father.
In a pair of cousins, the younger got his dad's looks and mom's personality and the older got his mom's looks and his dad's personality.
He suspects, for example, that fair hair and fair skin were less selected for in themselves than that they were by-products of something else that was being selected for in Europe.
Russian foxes bred for "tameness" (i.e. lack of fear & aggression) ended up with coloration differences not selected for. The theory is that adrenaline & melanin share a common biochemical pathway.
There were other physical differences as well.
http://scienceblogs.com/thoughtfulanimal/2010/06/monday_pets_the_russian_fox_st.php
In Europe, fairness is associated with northern latitudes and limited sunlight for a good deal of the year. Light skin maximizes vitamin D production which is critical for overall health (i.e. you don't need any fancy sex-selection theories to explain it).
Merely anecdotal but: I resemble my mother but have my father's disposition, my brother resembles my father and has my mother's disposition.
There are reasons for suspecting that sexual selection caused the diverse palette of European hair and eye colors. Let me sum them up.
When modern humans spread out of Africa some 50,000 years ago, they had only one allele at the MC1R gene (the main hair-color gene). Today, there are 11 MC1R alleles in Europeans, 5 in East Asians, and 1 in Africans. Phenotypically, this diversification is confined to Europeans (the East Asian alleles differ little in their effects). The species norm of black hair thus gave way among Europeans to a diverse range of brighter hues: brown, flaxen, golden, and red hair.
Meanwhile, at another gene, the same diversification happened with eye color. The species norm of brown eyes gave way to blue, gray, hazel, and green eyes.
Both of these processes occurred very quickly, perhaps over only 5,000 years. They certainly occurred after 20,000 BP -- when ancestral East Asians split off from ancestral Europeans. Such a short timespan implies not only selection, but also very intense selection.
Did hair and eye color become more diverse because of relaxed selection for dark skin? Harding et al. (2000) investigated this scenario and found that the time to the most recent common ancestral hair color would need to be about a million years, with the redhead alleles alone being c. 80,000 years old. Templeton (2002) came to a similar conclusion: if the cause were relaxation of selection, the current level of hair color diversity would have taken 850,000 years to develop. Yet modern humans have been in Europe for only 35,000 years or so.
Did hair and eye color diversify because of selection for light skin? Again, this is unlikely. For one thing, such selection would not increase the overall number of alleles. For another, the relationship between skin color, hair color, and eye color is problematic. Some hair-color alleles (notably for red hair) show a strong relationship with skin color. Most do not.
Color polymorphisms are generated by sexual selection, particularly when such selection is so intense that "eye-catching" features can make the difference between success and failure in finding a mate. Bright, novel colors attract attention much more than dull, common ones. The result is a balanced polymorphism that maximizes color brightness and color novelty.
For more, please read:
Frost, P. (2008). Sexual selection and human geographic variation, Proceedings of the 2nd Annual Meeting of the NorthEastern Evolutionary Psychology Society, The Journal of Social, Evolutionary & Cultural Psychology 2 (supp.): 49-65, www.jsecjournal.com/NEEPSfrost.pdf
Frost, P. (2006). European hair and eye color - A case of frequency-dependent sexual selection? Evolution and Human Behavior 27: 85-103 http://www.sciencedirect.com/science/journal/10905138
"He suspects, for example, that fair hair and fair skin were less selected for in themselves than that they were by-products of something else that was being selected for in Europe."
Probably, blue eyes.
Think of hairy-chested alpha male Burt Reynolds vs. effete girly men like Johnny Depp today.
Trust me on this, male body hair is a huge turn-off for women. The hairy-chested (and hairy-backed, hairy-shouldered, hairy-eared) alpha male look has gone the way of the pompadour.
Women and fashionistas want men to
be tall, muscular, and as hairless as possible. They think that means smart and civilized. In reality, the smartest (AND MOST CREATIVE) men aren't the plastic-skinned androids but rather the hairy little hobbits.
In a society where women increasingly want men who do as they're told, the last thing they want is a man's man as a partner.
No, too many women want an obedient robot who looks and feels like a "man's man".
Correction, a gay man's man.
Maybe blond hair and blue eyes are linked to genetic weakness and therefore display conspicuous consumption- if you can afford them, you must be well-fed.
I gues that's what cochran hates about sex selection. You think up a way something is useful, then say 'sex selection accounts for this useful trait.' Or think up a way something is useless and harmful; then say whoever has it is conspicuously consuming resources -chicks dig that.
Overexplanatory.
Remember the study that showed that brown-eyed Euro males tended to be more attractive than blue-eyed ones even when eye color was disguised? That could be a clue.
What was the correlation between skin color and IQ? Perhaps the red blond hair and blue eyes are correlated to fair skin and higher IQ?
He suspects, for example, that fair hair and fair skin were less selected for in themselves than that they were by-products of something else that was being selected for in Europe.
Maybe a higher vitamin d level.
Tough question. Hormones affect our face and how we think, so it is certainly possible. I think the answer is yes, on average. For instance, men who are extremely good at math tend to be baby-faced because of low testosterone levels.
"Remember the study that showed that brown-eyed Euro males tended to be more attractive than blue-eyed ones even when eye color was disguised? That could be a clue."
It was because the guys with brown eyes had more masculine features (broad chin, thick eyebrows, etc.).
My bet would be that northern Europeans were selecting for the heavy parental investment from men and that blue eyes were a side effect of it. Who do you think would make a better dad: a Swede or an Italian?
light eye color = dad
dark eye color = cad
Tough question. Hormones affect our face and how we think, so it is certainly possible. I think the answer is yes, on average. For instance, men who are extremely good at math tend to be baby-faced because of low testosterone levels.
Baby-faced features mask higher testosterone levels.
This is true in both men and women.
Remember the study that showed that brown-eyed Euro males tended to be more attractive than blue-eyed ones even when eye color was disguised? That could be a clue.
I want to see the experiment performed with both women and children. I will bet that men find blue-eyed women more attractive even when eye color is disguised, and that both men and women find blue-eyed kids more appealing even when they're browned out.
IIRC, there was a study a few years back showing that the blues outperformed the browns on longer term strategy tests or some such? I'd bet blue eyes goes with a couple changes in personality. I'd even bet that heterozygous brown-eyed people show the personality shift.
Here is another bit of anecdotal evidence:
When I was a kid, I had a friend whose younger brothers were fraternal twins. One looked exactly like their mom (petite, dark skin and hair) and the other looked like their dad (tall, fair skin and hair).
We moved away when we were all kids and I don't remember much about them.
For an unrelated reason, Mom and I were talking about them recently. Mom had noticed that each parent tended to carry around the twin that looked the most like themselves. She had even mentioned it to them and they were surprised and resolved to split their time more evenly.
Because we didn't keep in contact, I don't know how their personalities turned out. However, I see from some Facebook snooping that they still look very much different, and the one that looks like the dad is also a musician (like the dad).
It's an interesting thought.
Merely anecdotal but: I resemble my mother but have the disposition of the guy who used to deliver the groceries to our house.
Er...
Oh dear.
"For an unrelated reason, Mom and I were talking about them recently. Mom had noticed that each parent tended to carry around the twin that looked the most like themselves. She had even mentioned it to them and they were surprised and resolved to split their time more evenly."
There is something to it. Although my parents are similar looking in that they are both petite and dark-haired, I resemble my Dad more in the face and my sister resembles Mom. Incidentally, my Dad has always been more involved in my life than my Mom whom I clash with.
Correction - the link has been changed for the second journal article:
Frost, P. (2008). Sexual selection and human geographic variation, Special Issue: Proceedings of the 2nd Annual Meeting of the NorthEastern Evolutionary Psychology Society. Journal of Social, Evolutionary, and Cultural Psychology, 2(4), pp. 169-191.
http://www.jsecjournal.com/articles/volume2/issue4/NEEPSfrost.pdf
Tod
Johnny Depp is considered girly? Since when? It couldn't be more of the opposite. My only guess to why someone who would think this is the long length he often has his hair. Besides that, he has a strong defined jaw, cheekbones which I always thought were masculine features...
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