4 ms·

I share DNA with blue-green algae and would hope I share a bit more with someone who looks like me.

dekhn 4y ago
Sure, but that's not the narrative of this research result. The narrative is that people who look similar have similar DNA- by some metric, a person clusters more closely to people who are visually similar. But, it's really hard to tease out how much of that is population structure (for example, siblings resemble each other and their parents to a high degree, and people from populations that were isolated for long periods resemble each other), and what/how much in facial structure is caused by specific genes. And what the differences are between people, genetically. Complex phenotypes like face shapes aren't trivially determined by a single gene . Instead, the face is formed through the interactions by many gene products, and the differences in genotypes between individuals contribute in highly non-linear ways. For many years people tried to apply fairly simple reasoning (first just mendelian, then later SNPs, then copy number, then SNVs) on small numbers of genes but you can't explain all the hereditable genotype/phenotype variation without the whole genome (and possibly the epigenome). For faces they generally noticed a bunch of changes in a subset of genes that are involved with embryonic and later development. And specific patterns of changes across multiple genes. It's generally believed now that we could sequence millions of people and take normalized photos of their faces (see eigenfaces), sampling roughly from global population clusters in a balanced way, and build a joint genotype/phenotype embedding that would allow us to probe those complex, multivariate, non-linear rules. You would be able to do prediction and generation (given this genotype, show the most probable phenotype/face, or given this face, give a plausible genotype). Unfortunately this would be a highly politicized process makign it challenging to complete.
- fakethenews2022 4y ago
  You are way overthinking this and going down a rabbit hole of your own making. Facial features are correlated with and coevolve with other group/tribal characteristics. See the proliferation of blonde hair, tallness in the Dutch, prevalence of epicanthic folds, stockiness of bodies in colder climes, etc...
  - fakethenews2022 4y ago
    See also relatively isolated populations and how they look distinct. There are population bottlenecks, sexual selection, natural selection, etc...
  - dekhn 4y ago
    Overthinking this? Rabbit hole? I've worked in the area for ~3 decades. I don't even understand what point you're making, beyond what I just said. We know facial features are correlated with population structure, but that's an "average" effecet. I'm saying we can predict/explain the high resolution details of individual face structure from genotype, which is not yet possible.
    - cestith 4y ago
      Okay, I've read this archive of the article. I see some resemblance in the people in the photos, but I really, seriously could tell any pair of these people apart after spending about 30 seconds with them. I might think they were siblings or cousins if I didn't know better, but they are not easily mistaken for one another like "dopplegänger" suggests. But that goes to the same point, doesn't it? That we just expect this to be true, that people who resemble one another probably do because they share some genes? It seems so much as that suspicion is confirmed could have been said without the hype running all through the article and headline. https://archive.ph/Z9jMU https://archive.ph/Z9jMU
    - fakethenews2022 4y ago
      You are on your own side quest to predict facial structure from genotype. That and perhaps intelligence agencies. Your quest makes you concerned with discerning from averages. Outside your world, people don't have to be concerned with averages. Instead, they can see multiple correlated features. Perhaps a jawline, a brow, and a hairline.
- cestith 4y ago
  All that and a single offhanded mention of epigenetics and no mention of methylation? I would guess that people who resemble me more than the average person would not just have more of the same genes, but especially more of the same expressed genes. What do I know, though? I'm not a geneticist. That said, though, you've typed something so unless you're sitting for the Turing test soon I'd guess you do resemble me more than a box turtle does. Knowing that features are influenced by genes, the idea that similar features imply similar genes is a very simple hypothesis to make. I'm a little puzzled why it's so interesting to test whether genetics and epigenetics influence appearance in 2022. To me, it's near meaningless unless they start with a very strict definition of resemblance. Is it based on some measurement or someone's subjective interpretation of who looks like whom? I'm not paying $4.25 a week to read TFA and I've been told I "look like" plenty of people I don't. There are two people I know of in the world who resembled me very closely at some point in my life. One was fairly local and I disbelieved he really looked so much like me until my own aunt approached him in public and he said he'd heard the same about me. The other was a guy I knew from a BBS (actually a talker, if anyone here knows what that is) who decided he had a crush on me and sent me a photo of himself. I printed it out, held it up beside my face, and my mother asked when I had that photo taken. Freaky resemblances do exist. Should I be surprised that the people who looked like me are closer genetically and possibly in traceable genealogy than another human of another gender, another nationality, another ethnicity, another culture, and another society?
  - dekhn 4y ago
    epigenetics got a lot of press a few years ago but in the long run it seems ot have a limited impact on the total variation seen in phenotype.
deleted 4y ago
[deleted]

Sure, but that's not the narrative of this research result. The narrative is that people who look similar have similar DNA- by some metric, a person clusters more closely to people who are visually similar. But, it's really hard to tease out how much of that is population structure (for example, siblings resemble each other and their parents to a high degree, and people from populations that were isolated for long periods resemble each other), and what/how much in facial structure is caused by specific genes. And what the differences are between people, genetically. Complex phenotypes like face shapes aren't trivially determined by a single gene . Instead, the face is formed through the interactions by many gene products, and the differences in genotypes between individuals contribute in highly non-linear ways. For many years people tried to apply fairly simple reasoning (first just mendelian, then later SNPs, then copy number, then SNVs) on small numbers of genes but you can't explain all the hereditable genotype/phenotype variation without the whole genome (and possibly the epigenome). For faces they generally noticed a bunch of changes in a subset of genes that are involved with embryonic and later development. And specific patterns of changes across multiple genes. It's generally believed now that we could sequence millions of people and take normalized photos of their faces (see eigenfaces), sampling roughly from global population clusters in a balanced way, and build a joint genotype/phenotype embedding that would allow us to probe those complex, multivariate, non-linear rules. You would be able to do prediction and generation (given this genotype, show the most probable phenotype/face, or given this face, give a plausible genotype). Unfortunately this would be a highly politicized process makign it challenging to complete.

fakethenews2022 4y ago
You are way overthinking this and going down a rabbit hole of your own making. Facial features are correlated with and coevolve with other group/tribal characteristics. See the proliferation of blonde hair, tallness in the Dutch, prevalence of epicanthic folds, stockiness of bodies in colder climes, etc...
- fakethenews2022 4y ago
  See also relatively isolated populations and how they look distinct. There are population bottlenecks, sexual selection, natural selection, etc...
- dekhn 4y ago
  Overthinking this? Rabbit hole? I've worked in the area for ~3 decades. I don't even understand what point you're making, beyond what I just said. We know facial features are correlated with population structure, but that's an "average" effecet. I'm saying we can predict/explain the high resolution details of individual face structure from genotype, which is not yet possible.
  - cestith 4y ago
    Okay, I've read this archive of the article. I see some resemblance in the people in the photos, but I really, seriously could tell any pair of these people apart after spending about 30 seconds with them. I might think they were siblings or cousins if I didn't know better, but they are not easily mistaken for one another like "dopplegänger" suggests. But that goes to the same point, doesn't it? That we just expect this to be true, that people who resemble one another probably do because they share some genes? It seems so much as that suspicion is confirmed could have been said without the hype running all through the article and headline. https://archive.ph/Z9jMU https://archive.ph/Z9jMU
  - fakethenews2022 4y ago
    You are on your own side quest to predict facial structure from genotype. That and perhaps intelligence agencies. Your quest makes you concerned with discerning from averages. Outside your world, people don't have to be concerned with averages. Instead, they can see multiple correlated features. Perhaps a jawline, a brow, and a hairline.
cestith 4y ago
All that and a single offhanded mention of epigenetics and no mention of methylation? I would guess that people who resemble me more than the average person would not just have more of the same genes, but especially more of the same expressed genes. What do I know, though? I'm not a geneticist. That said, though, you've typed something so unless you're sitting for the Turing test soon I'd guess you do resemble me more than a box turtle does. Knowing that features are influenced by genes, the idea that similar features imply similar genes is a very simple hypothesis to make. I'm a little puzzled why it's so interesting to test whether genetics and epigenetics influence appearance in 2022. To me, it's near meaningless unless they start with a very strict definition of resemblance. Is it based on some measurement or someone's subjective interpretation of who looks like whom? I'm not paying $4.25 a week to read TFA and I've been told I "look like" plenty of people I don't. There are two people I know of in the world who resembled me very closely at some point in my life. One was fairly local and I disbelieved he really looked so much like me until my own aunt approached him in public and he said he'd heard the same about me. The other was a guy I knew from a BBS (actually a talker, if anyone here knows what that is) who decided he had a crush on me and sent me a photo of himself. I printed it out, held it up beside my face, and my mother asked when I had that photo taken. Freaky resemblances do exist. Should I be surprised that the people who looked like me are closer genetically and possibly in traceable genealogy than another human of another gender, another nationality, another ethnicity, another culture, and another society?
- dekhn 4y ago
  epigenetics got a lot of press a few years ago but in the long run it seems ot have a limited impact on the total variation seen in phenotype.

deleted 4y ago

[deleted]