6 ms·

Can someone explain this for someone like me with no education in biology or psychology?

by dgrant 11y ago

JoeAltmaier 11y ago
Sadly that may be impossible. Metaphors are limited - the understanding gained is always flawed and rarely actionable. A better question is, how much education in biology and psychology is needed to appreciate these findings?
- nitrogen 11y ago
  This is an interesting point and reminds me of the difference between technical and verbal understanding: http://www.yudkowsky.net/rational/technical/ http://www.yudkowsky.net/rational/technical/
jm_l 11y ago
For mentally challenged people, researchers have done an analysis of the distribution of certain genes that are associated with the handicap. They have shown with high likelihood that mental handicap is actually different than just being on the low end of the intelligence distribution. This study tries to answer the question, "is the same true for high intelligence?" The two general theories are the Continuity Hypothesis and Discontinuity Hypothesis. As its name suggests, the Continuity Hypothesis predicts that the high end of the intelligence distribution is continuous; extremely intelligence individuals don't violate the intelligence distribution the way mentally challenged people do. The Discontinuity Hypothesis predicts the opposite. By analyzing the genes of twins and other close family members, the researchers found strong evidence of the Continuity Hypothesis.
- soheil 11y ago
  I love how you accurately summarized a 10 page paper into a few concise sentences understandable most likely even by those on the low end of the intelligence distribution.
  - cba9 11y ago
    But he didn't; he stuffed the entire meat of the paper into 'By analyzing the genes of twins and other close family members'. To actually try to explain the design here: we think intelligence is caused by thousands of common genes, each of which slightly helps or hurts. When you have thousands of independent genes, then they add up to a normal distribution like the one we see when we measure a lot of people's intelligence. The exception is that there are too many retarded people; if the normal distribution was the whole story, then retarded people would be as rare as geniuses, but they are much more common than that. We explain there being too many retarded people by saying that they have one or a few very rare mutations, mutations which are very harmful. But another theory might be that the retarded have very few normal intelligence genes, or that intelligence genes don't simply add up but interact in complex ways, or that they have very harmful environments. How do we decide which theory is right? Well, we look at the retarded people vs their siblings; if their parents were lacking a lot of good genes, or they were being raised in a toxic waste dump, then we would expect the siblings to also be near-retarded themselves since they also inherited few good genes or are affected by the toxic waste. But they're not; they are almost average! This is more consistent with there being one bad mutation and the retarded sibling had bad luck than the other theories. This theory has since been confirmed by finding hundreds of unique and harmful mutations in retarded people. So we conclude that the effect of intelligence genes is indeed a normal distribution, with an occasional bad mutation overriding that and making someone retarded. This immediately raises a question. If we admit that on the low end intelligence may be controlled by a single rare mutation, why not on the high end too? Maybe there are special genius genes floating around. This would be important because it means that you can't make much progress by just looking at the genes of regular people, and it also means that SNP studies will be extremely limited in what they can find. How can we check this? We can do the same thing as on the low end: if there is a special genius gene, then geniuses will have much higher IQ than their siblings do, who will be close to average; but if their parents have lots of good genes and there is no single special gene, then the siblings will also be well above average and similar to their genius sibling. Using a very large set of siblings and twins, OP finds that very intelligent twins/teens are similar to their siblings. So this is the opposite of the retardation findings. There are rare genes for retardation, but there are not rare genes for genius.
- huangwei_chang 11y ago
  Thanks a lot for the summary. It is way better than reading the paper (I tried).
- btilly 11y ago
  BTW evolution theory suggests a priori that the Continuity Hypothesis is more likely to be correct. Intelligence is selected for in humans. Therefore any individual gene that significantly boosts intelligence should be expected to have already spread through the population. As a result we should not expect to find any rare genes that make people super-smart. So super-smart people get there with a combination of different genes, each of which contributes very little. The bottom end of the scale is the opposite story. Evolution says that individual genes that hurt intelligence should be selected against, and are therefore expected to be rare. (Mutation says that they should not be non-existent, but they should be rare.) Therefore there is no surprise in finding rare individual genes that significantly hurt intelligence. This pattern is not unique to intelligence. It is predicted for any trait that has actively been selected for by evolution over a long period. The top of the range should look continuous. The bottom of the range tends to be dominated by deleterious point mutations.
  - deleted 11y ago
    [deleted]
  - idanoeman 11y ago
    Intelligence is selected for in humans. Therefore any individual gene that significantly boosts intelligence should be expected to have already spread through the population, or has a trade-off that reduces reproductive fitness. The same can be said with drugs -- any chemical that your body could have reasonably produced on its own should be expected to reduce your reproductive fitness. So brain drugs should nearly all have side-effects.
kylemathews 11y ago
The researchers did a study of Swedish military conscripts (98%) of male population. They tested if high-intelligence is as inheritable as general-intelligence. They found strong evidence that it does as siblings of high-intelligent soldiers also tended to more intelligent than the norm.
- ambicapter 11y ago
  How does that show anything. Can't you assume that siblings would be raised in similar environments?
  - themetrician 11y ago
    Similar levels of intelligence have been seen even in switched-at-birth twin cases where one twin is raised by one family and another by another. The IQ between the twins was in every case more correlated than the IQ of each twin and their family-siblings. Look up the interview with Nancy Segal on YouTube about Twin Studies and IQ.
  - bpodgursky 11y ago
    Why is the comment by themetrician dead? (sibling to comment here) I don't understand.
  - femto113 11y ago
    They controlled for environment by considering the difference between non-twin siblings (< 2 years apart in age), fraternal (two-egg) twins, and identical (single-egg) twins. The correlation in intelligence between non-twin siblings and fraternal twins was similar, and both are significantly lower than the correlation between identical twins. The most plausible explanation for this is the genes that identical twins share.
  - vox_mollis 11y ago
    Nearly every twin study done in the history of twin studies has demonstrated minimal effects of shared environment on outcomes.
gragas 11y ago
Abstract High intelligence (general cognitive ability) is fundamental to the human capital that drives societies in the information age. Understanding the origins of this intellectual capital is important for government policy, for neuroscience, and for genetics. For genetics, a key question is whether the genetic causes of high intelligence are qualitatively or quantitatively different from the normal distribution of intelligence. We report results from a sibling and twin study of high intelligence and its links with the normal distribution. We identified 360,000 sibling pairs and 9000 twin pairs from 3 million 18-year-old males with cognitive assessments administered as part of conscription to military service in Sweden between 1968 and 2010. We found that high intelligence is familial, heritable, and caused by the same genetic and environmental factors responsible for the normal distribution of intelligence. High intelligence is a good candidate for “positive genetics” — going beyond the negative effects of DNA sequence variation on disease and disorders to consider the positive end of the distribution of genetic effects.
apalmer 11y ago
More or less the main crux is high intelligence is just a 'normal' manifestation of regular genes. Take height as an example, most people tall or short have 'regular' genetics for their height. A bunch of different factors play together along with the environment to lead to the height they actually have. its basically like a 1000 different genes interacting that each may give you or take a way a fraction of an inch and all together they sum up to your actual height. However sometimes you have people who are dwarfs, these arent just a combination of many genes, there is a overwhelming specific set of a few genes that totally overwhelm all the other height genes and give you greatly reduced height. Similarly on the other end of the spectrum you have some forms of giantism where a few genes overwhelm all the other height genes and give you greatly increased height. This study is more or less saying high intelligence follows a model like regular tall height, many different genes interacting to sum up to above average height. Not a model like giantism or dwarfism where a very limited number of genes overwhelm the 'normal' genetics of intelligence.
powertower 11y ago
They wanted to know what accounts for the difference between the high-intelligence group and the average-intelligence group. > (1) we conclude that high intelligence is familial, heritable, (2) and caused by the same genetic factors responsible for the normal distribution of intelligence. The 1st part is simple to understand, what is confusing everyone is the 2nd part... As the combination of both parts does not make sense (due to the type of "interpretation" presented). Here is the clearer version - (1) They found that intelligence was mostly hereditary (inherited via genes passed on by parents). (2) They further found that the top scorers could also be divided into their own bell-curve. That the high-intelligence group had there own distribution that followed the same pattern (which gives the bell-curve even more validity). To understand #2 just imagine a smart kid (in high-school) getting accepted into MIT, and once in, that smart kid finding out that he is now just "average" compared to some of the others. These conclusions are very politically-incorrect, especially for a progressive country like Sweden where you are not supposed to even acknowledge that different dog breeds have different behaviors.
- GPGPU 11y ago
  Of course, you can get into all sorts of trouble if you say that there's even such a thing as "intelligence" and that not everyone can be as brilliant as Einstein if they'd just had the right advantages as a child.
- GPGPU 11y ago
  Of course, you can get into all sorts of trouble if you say that there's even such a thing as "intelligence" and that not everyone can be as brilliant as Einstein if they'd just had the right advantages as a child.
- escherplex 11y ago
  Point number two above is well taken. Also there's more 'stretching' at the higher end. For example you may find a couple of individuals who can do complex del functions on a variety of topics in their head and somehow seem 'inspired' whereas others specialize on one arcane topic and spend countless weeks feeding research data into matlab or Wolfram apps while scouring onscreen .pdf tech archives for suitable algorithms they can adapt. But at this stage of the game functional genomics is in its infancy (you can't yet feed a genome's UCAG sequence into your 3D printer and expect it objectify a true object). For fuller understanding of implicit nature / nurture parameters concerning intelligence it may be more practical to select and isolate a suitably large sample from the center of the general population, where (dy/dx) = -yx is relatively flat, and insert such into a distraction-free positive artificial environment which focuses primarily on intellectual development and includes cognitive enhancement medical supplements such as nootropics or whatnot to varying degrees. Results may suggest high-intelligence is more latent than suspected, especially if sub bell curve distributions manifest.

Can someone explain this for someone like me with no education in biology or psychology?

by dgrant 11y ago

Can someone explain this for someone like me with no education in biology or psychology?

Sadly that may be impossible. Metaphors are limited - the understanding gained is always flawed and rarely actionable. A better question is, how much education in biology and psychology is needed to appreciate these findings?

nitrogen 11y ago
This is an interesting point and reminds me of the difference between technical and verbal understanding: http://www.yudkowsky.net/rational/technical/ http://www.yudkowsky.net/rational/technical/

jm_l 11y ago

For mentally challenged people, researchers have done an analysis of the distribution of certain genes that are associated with the handicap. They have shown with high likelihood that mental handicap is actually different than just being on the low end of the intelligence distribution. This study tries to answer the question, "is the same true for high intelligence?" The two general theories are the Continuity Hypothesis and Discontinuity Hypothesis. As its name suggests, the Continuity Hypothesis predicts that the high end of the intelligence distribution is continuous; extremely intelligence individuals don't violate the intelligence distribution the way mentally challenged people do. The Discontinuity Hypothesis predicts the opposite. By analyzing the genes of twins and other close family members, the researchers found strong evidence of the Continuity Hypothesis.

soheil 11y ago
I love how you accurately summarized a 10 page paper into a few concise sentences understandable most likely even by those on the low end of the intelligence distribution.
- cba9 11y ago
  But he didn't; he stuffed the entire meat of the paper into 'By analyzing the genes of twins and other close family members'. To actually try to explain the design here: we think intelligence is caused by thousands of common genes, each of which slightly helps or hurts. When you have thousands of independent genes, then they add up to a normal distribution like the one we see when we measure a lot of people's intelligence. The exception is that there are too many retarded people; if the normal distribution was the whole story, then retarded people would be as rare as geniuses, but they are much more common than that. We explain there being too many retarded people by saying that they have one or a few very rare mutations, mutations which are very harmful. But another theory might be that the retarded have very few normal intelligence genes, or that intelligence genes don't simply add up but interact in complex ways, or that they have very harmful environments. How do we decide which theory is right? Well, we look at the retarded people vs their siblings; if their parents were lacking a lot of good genes, or they were being raised in a toxic waste dump, then we would expect the siblings to also be near-retarded themselves since they also inherited few good genes or are affected by the toxic waste. But they're not; they are almost average! This is more consistent with there being one bad mutation and the retarded sibling had bad luck than the other theories. This theory has since been confirmed by finding hundreds of unique and harmful mutations in retarded people. So we conclude that the effect of intelligence genes is indeed a normal distribution, with an occasional bad mutation overriding that and making someone retarded. This immediately raises a question. If we admit that on the low end intelligence may be controlled by a single rare mutation, why not on the high end too? Maybe there are special genius genes floating around. This would be important because it means that you can't make much progress by just looking at the genes of regular people, and it also means that SNP studies will be extremely limited in what they can find. How can we check this? We can do the same thing as on the low end: if there is a special genius gene, then geniuses will have much higher IQ than their siblings do, who will be close to average; but if their parents have lots of good genes and there is no single special gene, then the siblings will also be well above average and similar to their genius sibling. Using a very large set of siblings and twins, OP finds that very intelligent twins/teens are similar to their siblings. So this is the opposite of the retardation findings. There are rare genes for retardation, but there are not rare genes for genius.
huangwei_chang 11y ago
Thanks a lot for the summary. It is way better than reading the paper (I tried).
btilly 11y ago
BTW evolution theory suggests a priori that the Continuity Hypothesis is more likely to be correct. Intelligence is selected for in humans. Therefore any individual gene that significantly boosts intelligence should be expected to have already spread through the population. As a result we should not expect to find any rare genes that make people super-smart. So super-smart people get there with a combination of different genes, each of which contributes very little. The bottom end of the scale is the opposite story. Evolution says that individual genes that hurt intelligence should be selected against, and are therefore expected to be rare. (Mutation says that they should not be non-existent, but they should be rare.) Therefore there is no surprise in finding rare individual genes that significantly hurt intelligence. This pattern is not unique to intelligence. It is predicted for any trait that has actively been selected for by evolution over a long period. The top of the range should look continuous. The bottom of the range tends to be dominated by deleterious point mutations.
- deleted 11y ago
  [deleted]
- idanoeman 11y ago
  Intelligence is selected for in humans. Therefore any individual gene that significantly boosts intelligence should be expected to have already spread through the population, or has a trade-off that reduces reproductive fitness. The same can be said with drugs -- any chemical that your body could have reasonably produced on its own should be expected to reduce your reproductive fitness. So brain drugs should nearly all have side-effects.

kylemathews 11y ago

The researchers did a study of Swedish military conscripts (98%) of male population. They tested if high-intelligence is as inheritable as general-intelligence. They found strong evidence that it does as siblings of high-intelligent soldiers also tended to more intelligent than the norm.

ambicapter 11y ago
How does that show anything. Can't you assume that siblings would be raised in similar environments?
- themetrician 11y ago
  Similar levels of intelligence have been seen even in switched-at-birth twin cases where one twin is raised by one family and another by another. The IQ between the twins was in every case more correlated than the IQ of each twin and their family-siblings. Look up the interview with Nancy Segal on YouTube about Twin Studies and IQ.
- bpodgursky 11y ago
  Why is the comment by themetrician dead? (sibling to comment here) I don't understand.
- femto113 11y ago
  They controlled for environment by considering the difference between non-twin siblings (< 2 years apart in age), fraternal (two-egg) twins, and identical (single-egg) twins. The correlation in intelligence between non-twin siblings and fraternal twins was similar, and both are significantly lower than the correlation between identical twins. The most plausible explanation for this is the genes that identical twins share.
- vox_mollis 11y ago
  Nearly every twin study done in the history of twin studies has demonstrated minimal effects of shared environment on outcomes.

gragas 11y ago

Abstract High intelligence (general cognitive ability) is fundamental to the human capital that drives societies in the information age. Understanding the origins of this intellectual capital is important for government policy, for neuroscience, and for genetics. For genetics, a key question is whether the genetic causes of high intelligence are qualitatively or quantitatively different from the normal distribution of intelligence. We report results from a sibling and twin study of high intelligence and its links with the normal distribution. We identified 360,000 sibling pairs and 9000 twin pairs from 3 million 18-year-old males with cognitive assessments administered as part of conscription to military service in Sweden between 1968 and 2010. We found that high intelligence is familial, heritable, and caused by the same genetic and environmental factors responsible for the normal distribution of intelligence. High intelligence is a good candidate for “positive genetics” — going beyond the negative effects of DNA sequence variation on disease and disorders to consider the positive end of the distribution of genetic effects.

apalmer 11y ago

More or less the main crux is high intelligence is just a 'normal' manifestation of regular genes. Take height as an example, most people tall or short have 'regular' genetics for their height. A bunch of different factors play together along with the environment to lead to the height they actually have. its basically like a 1000 different genes interacting that each may give you or take a way a fraction of an inch and all together they sum up to your actual height. However sometimes you have people who are dwarfs, these arent just a combination of many genes, there is a overwhelming specific set of a few genes that totally overwhelm all the other height genes and give you greatly reduced height. Similarly on the other end of the spectrum you have some forms of giantism where a few genes overwhelm all the other height genes and give you greatly increased height. This study is more or less saying high intelligence follows a model like regular tall height, many different genes interacting to sum up to above average height. Not a model like giantism or dwarfism where a very limited number of genes overwhelm the 'normal' genetics of intelligence.

powertower 11y ago

They wanted to know what accounts for the difference between the high-intelligence group and the average-intelligence group. > (1) we conclude that high intelligence is familial, heritable, (2) and caused by the same genetic factors responsible for the normal distribution of intelligence. The 1st part is simple to understand, what is confusing everyone is the 2nd part... As the combination of both parts does not make sense (due to the type of "interpretation" presented). Here is the clearer version - (1) They found that intelligence was mostly hereditary (inherited via genes passed on by parents). (2) They further found that the top scorers could also be divided into their own bell-curve. That the high-intelligence group had there own distribution that followed the same pattern (which gives the bell-curve even more validity). To understand #2 just imagine a smart kid (in high-school) getting accepted into MIT, and once in, that smart kid finding out that he is now just "average" compared to some of the others. These conclusions are very politically-incorrect, especially for a progressive country like Sweden where you are not supposed to even acknowledge that different dog breeds have different behaviors.

GPGPU 11y ago
Of course, you can get into all sorts of trouble if you say that there's even such a thing as "intelligence" and that not everyone can be as brilliant as Einstein if they'd just had the right advantages as a child.
GPGPU 11y ago
Of course, you can get into all sorts of trouble if you say that there's even such a thing as "intelligence" and that not everyone can be as brilliant as Einstein if they'd just had the right advantages as a child.
escherplex 11y ago
Point number two above is well taken. Also there's more 'stretching' at the higher end. For example you may find a couple of individuals who can do complex del functions on a variety of topics in their head and somehow seem 'inspired' whereas others specialize on one arcane topic and spend countless weeks feeding research data into matlab or Wolfram apps while scouring onscreen .pdf tech archives for suitable algorithms they can adapt. But at this stage of the game functional genomics is in its infancy (you can't yet feed a genome's UCAG sequence into your 3D printer and expect it objectify a true object). For fuller understanding of implicit nature / nurture parameters concerning intelligence it may be more practical to select and isolate a suitably large sample from the center of the general population, where (dy/dx) = -yx is relatively flat, and insert such into a distraction-free positive artificial environment which focuses primarily on intellectual development and includes cognitive enhancement medical supplements such as nootropics or whatnot to varying degrees. Results may suggest high-intelligence is more latent than suspected, especially if sub bell curve distributions manifest.