5 ms·

Please take the article with a huge grain of salt. Hundreds of millions of years ago, vertebrate eyes originally evolved backwards. Evolution hill-climbs, so th

by ggreer 11y ago

Please take the article with a huge grain of salt. Hundreds of millions of years ago, vertebrate eyes originally evolved backwards. Evolution hill-climbs, so the backwardness (and ensuing disadvantages like the blind spot) can never be fixed. Tricks with glial cells are nature making the best of a bad deal. Also, the author's ignorance of biology concerns me. In one comment, he thought that color-blind people saw in grayscale. If you know how human cone and rod cells are set up, such an idea seems preposterous.

BoardsOfCanada 11y ago
Exactly, it feels very strange that anyone would find it "rather curious" that the eye has evolved toward a local optimum. And moving the wiring out of the light's path would allow for even more of this concentration mechanism in front of the retina.
brudgers 11y ago
The picture of the guinea pig says a lot about the intellectual heft of the article...fluffy and not addressing the scientific reality. I'm not a member of PETA, but thinking about the messy reality of experiments on guinea pig eyes is not something I take as being without karmic costs. Grass, sunshine and a bowl of kibble are not what laboratory experiments on animals conjure to my mind.
wyager 11y ago
>Evolution hill-climbs, so the backwardness (and ensuing disadvantages like the blind spot) can never be fixed. Well, there's some randomness in there too. I'm sure genetic local maxima get busted sometimes.
- Retra 11y ago
  The problem with randomness is that it is overwhelmingly likely to produce worse performance, not better. So much so, that it is practically impossible to improve through random effects.
  - verbin217 11y ago
    It's really not all that impossible for singular mutations, hence evolution. Further, adaptations composed of independently maladaptive mutations can occur. This is the point of the comment you responded to. They are unlikely, but he alluded to that.
  - zck 11y ago
    Random mutations don't have to produce better performance to end up with better results. They just need: 1. To move you to a "bigger hill". Imagine going from no eyes to skin spots that are slightly more delicate than regular skin, but are precursors of light-sensing skin cells^1. Over the course of generations, eyes can evolve. 2. To not be too deleterious. One spot of more sensitive skin won't cause the mutation to be immediately evolved away from; it's just not that bad for the individual. When you say it's "practically impossible to improve through random effects", what is "practically impossible"? How have you weighed that against the number of individuals in a population, the number of random mutations each offspring has, and the length of time we're talking about? The question isn't "what are the chances a blind fish today has a baby with eyes tomorrow?" This question both understates the number of trials evolution has to generate something, and pins the target of evolution. Instead, we should ask "over millions of years, what are the chances that a given population evolves something useful?" [1] I'm not claiming this is exactly how eyes evolved.
    - Retra 11y ago
      There are two different concepts at play here. The first is the notion of optimization by randomness and the second is evolution by natural selection. For the first issue, there are is a simple way of seeing what I'm talking about; If you are trying to optimize an algorithm for given results, there are three broad techniques which I will categorize for simplicity as 'stupid', 'random', and 'smart.' For instance, if I wanted to sort a deck of cards, I could just shuffle it until I had a sorted deck. That's 'random.' This is not the worst you can do, and only if you do worse can random be an improvement. To do worse, you have to actively prevent the deck from becoming sorted. (For example, by using an algorithm that guarantees a 1-3-2 order at the start.) Randomness is not optimization, and stupidity is optimization away from the goal. Smart is convergence on a goal. However, evolution is not a goal directed process. Those who exist are simply those who lived long enough in the environments they happened find themselves. Randomness doesn't improve any organism or any feature of any organism: it only improves diversity, which allows for more niches to be filled. I mean, maybe this increases the availability of food or the amount of space per organism or something, but it doesn't actually improve organisms. It improves the environment by making it less hostile to life in the abstract. So it has nothing to do with hill climbing or optimization per se.
mtooth 11y ago
You make a good point regarding the author's understanding of color blindness, however gray-scale vision absolutely does exist in humans, albeit in a much smaller proportion of the population than common red-green colorblindness: https://en.wikipedia.org/wiki/Achromatopsia https://en.wikipedia.org/wiki/Achromatopsia

by ggreer 11y ago

BoardsOfCanada 11y ago

Exactly, it feels very strange that anyone would find it "rather curious" that the eye has evolved toward a local optimum. And moving the wiring out of the light's path would allow for even more of this concentration mechanism in front of the retina.

brudgers 11y ago

The picture of the guinea pig says a lot about the intellectual heft of the article...fluffy and not addressing the scientific reality. I'm not a member of PETA, but thinking about the messy reality of experiments on guinea pig eyes is not something I take as being without karmic costs. Grass, sunshine and a bowl of kibble are not what laboratory experiments on animals conjure to my mind.

wyager 11y ago

>Evolution hill-climbs, so the backwardness (and ensuing disadvantages like the blind spot) can never be fixed. Well, there's some randomness in there too. I'm sure genetic local maxima get busted sometimes.

Retra 11y ago
The problem with randomness is that it is overwhelmingly likely to produce worse performance, not better. So much so, that it is practically impossible to improve through random effects.
- verbin217 11y ago
  It's really not all that impossible for singular mutations, hence evolution. Further, adaptations composed of independently maladaptive mutations can occur. This is the point of the comment you responded to. They are unlikely, but he alluded to that.
- zck 11y ago
  Random mutations don't have to produce better performance to end up with better results. They just need: 1. To move you to a "bigger hill". Imagine going from no eyes to skin spots that are slightly more delicate than regular skin, but are precursors of light-sensing skin cells^1. Over the course of generations, eyes can evolve. 2. To not be too deleterious. One spot of more sensitive skin won't cause the mutation to be immediately evolved away from; it's just not that bad for the individual. When you say it's "practically impossible to improve through random effects", what is "practically impossible"? How have you weighed that against the number of individuals in a population, the number of random mutations each offspring has, and the length of time we're talking about? The question isn't "what are the chances a blind fish today has a baby with eyes tomorrow?" This question both understates the number of trials evolution has to generate something, and pins the target of evolution. Instead, we should ask "over millions of years, what are the chances that a given population evolves something useful?" [1] I'm not claiming this is exactly how eyes evolved.
  - Retra 11y ago
    There are two different concepts at play here. The first is the notion of optimization by randomness and the second is evolution by natural selection. For the first issue, there are is a simple way of seeing what I'm talking about; If you are trying to optimize an algorithm for given results, there are three broad techniques which I will categorize for simplicity as 'stupid', 'random', and 'smart.' For instance, if I wanted to sort a deck of cards, I could just shuffle it until I had a sorted deck. That's 'random.' This is not the worst you can do, and only if you do worse can random be an improvement. To do worse, you have to actively prevent the deck from becoming sorted. (For example, by using an algorithm that guarantees a 1-3-2 order at the start.) Randomness is not optimization, and stupidity is optimization away from the goal. Smart is convergence on a goal. However, evolution is not a goal directed process. Those who exist are simply those who lived long enough in the environments they happened find themselves. Randomness doesn't improve any organism or any feature of any organism: it only improves diversity, which allows for more niches to be filled. I mean, maybe this increases the availability of food or the amount of space per organism or something, but it doesn't actually improve organisms. It improves the environment by making it less hostile to life in the abstract. So it has nothing to do with hill climbing or optimization per se.

mtooth 11y ago

You make a good point regarding the author's understanding of color blindness, however gray-scale vision absolutely does exist in humans, albeit in a much smaller proportion of the population than common red-green colorblindness: https://en.wikipedia.org/wiki/Achromatopsia https://en.wikipedia.org/wiki/Achromatopsia