> Deemed a neutral mutation, Eiberg says the eye-color example "simply shows that nature is constantly shuffling the human genome, creating a genetic cocktail of human chromosomes and trying out different changes as it does so."
Blue eyes tends to make people seem more attractive and the evolutionary reason is that they end up being a good quality in a mate because it's easier to see pupil dilation. Thus making it easier to perceive their emotional states better than of someone with black/brown eyes.
This is also true for pale eye colors in general(non-black and non-brown) which are perceived as more attractive, another reason being that they're rare and exclusive. This not just helps in finding better mates but also helps with survival, like how attractive or taller people are helped more in society or are promoted more. Like how almost all US presidents are tall.
Not sure what the technical defintion of a neutral mutation is, but I don't think this is one based on plain English, or I am just plain wrong.
When you analyze if attractiveness or height gives you a genetic/population advantage, you cannot stop at "they are promoted". They have to have more children, and the children have to also have genetic advantages.
For example, if you have a pale skin in Sweden 20.000 years ago, your vitamin D metabolism is better, so of your 5 children 4 reach adulthood healthy. Meanwhile, your black neighbor had 5 children and only 2 reached adulthood, and they have rickets. In a few generations, the skin gets white among the population.
But if you both lived in Africa, 4 of your 5 kids developed melanoma at young age. They either die or get horribly scarred. Meanwhile, your neighbor still has 4 healthy kids that never get sunburns. The amount of sunlight is so high that D vitamin is not an issue.
I saw this graphically when I was in the Namib desert. There was a family of Himba people who had an albino child. The boy had sores all over his body and had to stay under strong shade constantly. Poor kid was living a cursed life simply because he’d gotten a bad roll of the genetic dice.
Does it have to be beneficial? Another possibility is that the melanin production machinery just broke in a small population and the population was geographically isolated enough that the breakage wasn’t overwritten by neighbors (since there were no neighbors). I wonder if this has been ruled out somehow?
This is called genetic isolation, and it's the origin of many species. But when it happens you don't get a gradient. You get two populations separated by (usually) a geographic barrier.
The closest case I could imagine for this in humans are the australian aboriginals and papuans. You don't have a continuous gradient south-north between them and asian populations (assuming the Out Or Africa as true), but a sharp cut dated 50K years ago. Europeans are genetically closer to an asian than asians to papuans or australians.
Lets imagine a small group of engineers that develope a bad software pattern in full isolation. They don't know better, so they work in that way for years. Now suppose they get in contact again with the rest of the world. How could their bad pattern expand to the rest of the world engineers if it is inferior? The ones that addopt it would be selected against, the ones who doesn't would be selecter positively.
For it to expand it had to have at least something positive (unless you do a Chengis Khan). This is what happened to sickle cell disease, which is a bad mutation but gives you resistence to malaria, so the sickle cell disease is common in Africa. Meanwhile, African Americans have much less of the mutation, because in the USA there is no malaria, thus the gene is being slowly removed from the population.
I meant pale eye color, I edited the parent comment. It had nothing about skin color. And also eye color is just one dimension among hundreds, some of which you listed.
The first, second, and fourth links are about pupil dilation generally. They don’t say anything about eye color. They most certainly say nothing to support your assertions about the connection between eye color and the perception of pupil dilation.
The third link (the Reddit thread) does mention eye color but only in the context of the effects of dilating drugs (drops). This also is irrelevant to the topic at hand.
> They most certainly say nothing to support your assertions about the connection between eye color and the perception of pupil dilation
I would think this was common knowledge just from talking to a lot of people face to face but again this is HN with people of multiple backgrounds and people that don't like talking to people and spend a lot of time indoors, not to mention people who are not good at picking up emotional and social cues, so here's the reference from 1975.
> We also found that blue-eyed people have a stronger pupil response than brown-eyed people when they view a picture that causes pupil dilation or constriction. To be more precise, with respect to the total range of response from the smallest pupil size to the largest the range is greater for blue-eyed people than it is for brown-eyed people. (This statement applies, of course, only to changes in pupil size resulting from emotions or attitudes.)
> It is of course easier to see a pupil surrounded by a blue iris than it is to see one surrounded by a brown iris.
I see you are more interested in hurling insults than arguing your case in good faith. That’s fine but it means I am done responding to you after this comment.
> It is of course easier to see a pupil surrounded by a blue iris than it is to see one surrounded by a brown iris.
Again this is an undefended assertion. It’s important to remember we’re talking about subconscious responses to pupil size. Just because you (and Eckhard Hess) believe it is “easier” to consciously perceivr pupils surrounded by blue irises does not mean your subconscious is any less aware of pupils in brown eyes. If it’s true that it’s easier to subconsciously decode pupils in blue eyes then it should be easy to verify experimentally. Similarly, if it is easier to be aware of the emotional state of blue-eyed people then that should be easy to prove experimentally. What’s harder is showing your assertions that blue-eyed people thus make better partners or that this makes blue eyes an evolutionary advantage.
> It’s important to remember we’re talking about subconscious responses to pupil size. Just because you (and Eckhard Hess) believe it is “easier” to consciously perceivr pupils surrounded by blue irises does not mean your subconscious is any less aware of pupils in brown eyes.
Subconscious responses are still limited by physical limitations. If you don't believe, you can win the James Randi one million dollar prize by demonstrating it with an experiment. Maybe you can show that someone can subconsciously identify the shapes of a very black object placed in front of another very black object in a dark room.
> If it’s true that it’s easier to subconsciously decode pupils in blue eyes then it should be easy to verify experimentally
It's a proven fact that features are easier or harder to discern based on their background. For example a white cat is easier to see when it's almost pitch dark compared to a dark cat. Maybe someone like you can pioneer research in an experiment to formally prove it.
One can start by asking people which pupils are easier to discern from the iris in this picture. Pupils are black or a very dark color btw.
Compare top row to the rest. Now think about all the lighting conditions and distances that occur when people talk to or interact with other people. Of course there are people with vision impairments who won't notice the differences and may think they might all look the same. Scientists don't waste time trying to prove things already proven just because some internet troll debater may question things.
Hess' paper is quite well cited, so it should be easy to find any counter assertion to something that he stated with such high confidence: "It is of course". Maybe you can try finding one, but from this thread so far it seems like you're more interested in dismissing things for arguments' sake rather than try sourcing information like I have been doing.
> I see you are more interested in hurling insults than arguing your case in good faith. That’s fine but it means I am done responding to you after this comment.
You're the one that hasn't put in any research and just dismissing any scientific source I post. It's a pain and a waste of time to respond to low effort argumentative folks.
> You're the one that hasn't put in any research and just dismissing any scientific source I post. It's a pain and a waste of time to respond to low effort argumentative folks.
That's because your scientific sources are of questionable quality and don't support your hypothesis.
> so it should be easy to find any counter assertion to something that he stated with such high confidence: "It is of course".
More specifically Hess wrote "It is of course easier to see a pupil surrounded by a blue iris than it is to see one surrounded by a brown iris. Perhaps it is not unwarranted to assume that the response has been favored by evolutionary selection more in blue-eyed people than in brown-eyed people." (Emphasis mine.)
"Perhaps it is not unwarranted to assume" does not suggest high confidence.
> so it should be easy to find any counter assertion
I did a Google Scholar search for: "The Role of Pupil Size in Communication" blue brown
] As a means of clarifying certain of Hess' (1975) unsubstantiated conclusions concerning the role of pupil size in nonverbal communication, the relationship between eye color and the pupillary attributions of college students to Hess' happy-angry face task was measured. The results supported Hess' claim that eye color is related to sensitivity to pupillary cues but were incongruent with his notion that blue-eyed people are especially sensitive due to some selective evolutionary process.
The text describes issues with Hess's work, and how others at the time viewed Hess's conclusion:
] Hess offered no other evidence for this conclusion. That is, he did not bother to report any statistical evaluation of the differences between these means, nor did he provide the sample sizes and the standard deviations that would have permitted others to do so. Perhaps it is this lack of concern for relevant detail on Hess' part that led Ianisse (1977) to conclude, "it is difficult to seriously entertain the notion that the pupil plays a major role in nonverbal communication, for no convincing research has shown the proposed phenomenon to be veridical" (p.170). Ianisses's point is well taken, and perhaps even charitable, for Hess' apparent disdain for statistical evaluation of his data invites the speculation that possibly the obvious statistical tests were computed but were not reported because these results proved to be not significant.
and their attempt at replication showed that hazel-eyed people were more sensitive than blue-eyed people, but write that such an interpretation "would strain credibility":
] These results seem to be incongruent with Hess' conclusion that blue-eyed people have had some selective evolutionary advantage with respect to sensitivity to pupillary cues. While our data suggest that hazel-eyed people seem to be more sensitive to pupillary cues, we feel that it would strain credibility to attempt to explain these differences in terms of a selective evolutionary process as Hess did. In fact, any explanation of the processes that might have led to the differential sensitivity of browne, blue-, and hazel-eyed people to pupillary cues seems premature. For, as Janisse (1977) has correctly pointed out, it remains to be demonstrated that results such as these are veridical. Thus, subsequent research should focus on determining whether the apparent sensitivity advantages enjoyed by hazel- and perhaps blue-eyed individuals translate to more effective interpersonal skills.
It's hard to get much easier than that.
That part of Hess's research failed replication, just like how https://www.sciencedirect.com/science/article/pii/S016787602... ("Replicating five pupillometry studies of Eckhard Hess") showed how some (though not all) of Hess's work could not be replicated, and pointed out how "Hess mostly used small sample sizes and undocumented luminance control".
Why are you so certain of Hess's hypothesis when it seems to have been shot down over 40 years ago? If you know of any follow-up studies which showed the replication attempt could not be replicated, while the original could, please provide it.
Perhaps you can point to something more substantial than 50 year old research containing documented questionable accuracy?
Did you not find these follow-up papers in your attempts to understand this research? They were quite easy to find, while you seemed very certain they did not exist. What formed the basis of your confidence that Hess's hypothesis had not been challenged?
And remember, your claim is "the evolutionary reason is that [blue-eyed people] end up being a good quality in a mate because it's easier to see ... their emotional states", so supporting evidence must "focus on determining whether the apparent sensitivity advantages enjoyed by ... blue-eyed individuals translate to more effective interpersonal skills."
Which you have failed to do, preferring to make chains of correlations to support your argument.
But correlations are not generally transitive, so that argument is invalid.
>Blue eyes tends to make people seem more attractive and the evolutionary reason is that they end up being a good quality in a mate because it's easier to see pupil dilation. Thus making it easier to perceive their emotional states better than of someone with black/brown eyes.
I'm sure there are evolutionary disadvantages to not being able to hide your emotional states.
also the attractiveness of the color is probably taught and culturally defined.
Is this supposed to be some kind of subconscious thing? Because I’ve never noticed what anyone’s pupils are doing - and the majority of my family friends and light colored eyes, so, if this was actually a thing, I’d have lots of opportunities to experience it.
> The study found that the openness of the eye was most closely related to our ability to read others' mental states based on their eye expressions.
which is where you probably drew your conclusion. However, the actual paper goes into more details, and reading it show that conclusion is wrong. It says:
> For these analyses, we extracted seven eye features from each exemplar: vertical eye aperture, eyebrow distance, eyebrow slope, eyebrow curvature, nasal wrinkles, temporal wrinkles, and wrinkles below the eyes (Fig. 1). Euclidean coordinates from the appearance models were used to compute eye aperture (distance from top to bottom of eye), eyebrow distance (distance from top of eye to eyebrow), eyebrow slope (slope from start to end of eyebrow), and eyebrow curvature (angular change from start to end of eyebrow).
Fig. 1 in shows example of how they define eye aperture, and it is NOT the pupil size, but the size from the bottom to top of the center of the eye.
Further, their analysis suggests that eye pupil size is either strongly correlated with the seven components they analyzed, or has relatively small contribution to expressing mental state. They say aperture had the strongest correlation with mental-state, "explaining 61.7% of the variance; the valence dimension was the secondary component, explaining 26.8% of the variance. ... Together, these [seven] components captured 88.8% of the total variance."
That is, your claim about pupil size being an evolutionary benefit due to the increased ability to perceive mental state, appear to be contradicted by the very paper you say supports your hypothesis.
There's a long history where defenders of pseudoscience, including Young Earth Creationism and "scientific racism", of citing papers which supposedly support their claim, only to find that either they are irrelevant or say quite the opposites. If you want to make a solid claim, you need to avoid that style, otherwise you'll draw their pseudoscience stink onto you.
> We also found that blue-eyed people have a stronger pupil response than brown-eyed people when they view a picture that causes pupil dilation or constriction. To be more precise, with respect to the total range of response from the smallest pupil size to the largest the range is greater for blue-eyed people than it is for brown-eyed people. (This statement applies, of course, only to changes in pupil size resulting from emotions or attitudes.)
> It is of course easier to see a pupil surrounded by a blue iris than it is to see one surrounded by a brown iris.
That is the press release for the primary article, which is listed at the bottom of the page: Daniel H. Lee, Adam K. Anderson. Reading What the Mind Thinks From How the Eye Sees. Psychological Science, 2017; 28 (4): 494 DOI: 10.1177/0956797616687364
Lee and Anderson DO NOT talk about pupils. That's why irrational replied to your link with "Did you even read what you linked? The linked article has nothing to do with pupils."
I confirmed that irrational's observation is correct, despite your denial.
Your quote now comes from The Role of Pupil Size in Communication, Eckhard H. Hess, Scientific American, Vol. 233, No. 5 (November 1975), pp. 110-119.
The Lee and Anderson (2017), doesn't contradict Hess (1975). Rather, it says that any effect of pupil dilation size on the ability to perceive mental state is significantly smaller than several other factors related to the eye.
The Hess paper is a woefully inadequate source for your claim that blue eyes are not evolutionarily neutral. How many people were studied? How much stronger was the response? What is the statistical significance and how was it calculated? How does it compare to other ways the eyes signal mood like in Lee and Anderson? Were there conflating social factors, like the blue-eye subjects being from a higher social class on average than the brown-eyed subjects?
The paper doesn't give any of those numbers, which makes sense as Scientific American was on the border between an academic publication and a popular science magazine.
Furthermore, the author characterizes the evolutionary hypothesis as "perhaps it is not unwarranted" - a far more tentative claim than you are trying to push.
You need to fill in the missing steps. How do you get from "perhaps not unwarranted" to "substantive enough to advocate on HN"? Because you appear to be advocating an hypothesis with very little evidence.
There's been 50 years of research since Hess. My sampling of the recent papers citing Hess are completely silent of a blue/brown-eyed distinction, which suggests to me it did not play out.
How did you find the Lee and Anderson paper? When did you read it? Why did you cite it when it doesn't even mention the word "pupil"? Do you understand how it seems to strongly diminish the significance of your evolutionary hypothesis?
You definitely notice body language subconsciously, our scleras being visible is well known to play a role in determining where the other is looking for example.
yeah and there are already plenty of comments explaining how these are irrelevant- you can’t just connect adjacent studies by assumption and have those assumptions be true
gaganyaan, see also the followup where the presented citations doesn't support the claim for evolutionary benefit.
See also my comment at https://news.ycombinator.com/item?id=35679767 showing the 1975 hypothesis could not be validated in a 1979 paper, and how even at the time it was "difficult to seriously entertain the notion" Hess proposed.
See also the thread at https://news.ycombinator.com/item?id=35667066 where one of belltaco's citations actually demonstrates that total vertical eye aperture - not pupil size - is the biggest predictor of mental state. Pupil size wasn't even considered, but the remaining variance is too small for pupil size to be a significant predictor. Total aperture is even easier to see than pupil size.
In other words, there's a bunch of citations, but no convincing support presented for the evolutionary hypothesis.
Another take I’ve heard is that lighter eyes allow you to see the dark ring around the iris (limbic rings), which apparently fades as you age, becoming progressively lighter, forming a sort of proxy for age.
Blue eyes tends to make people seem more attractive and the evolutionary reason is that they end up being a good quality in a mate because it's easier to see pupil dilation. Thus making it easier to perceive their emotional states better than of someone with black/brown eyes.
This is also true for pale eye colors in general(non-black and non-brown) which are perceived as more attractive, another reason being that they're rare and exclusive. This not just helps in finding better mates but also helps with survival, like how attractive or taller people are helped more in society or are promoted more. Like how almost all US presidents are tall.
Not sure what the technical defintion of a neutral mutation is, but I don't think this is one based on plain English, or I am just plain wrong.