
Thinking positively: The genetics of high intelligence - gwern
http://www.sciencedirect.com/science/article/pii/S0160289614001676
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danieltillett
I would be very surprised if high intelligence was anything other than the
extreme edge of a normal distribution of the human population. For it to be
anything other than this it would require people of high intelligence to be a
sub-population that did not breed with the rest of humanity.

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vixen99
'would require people of high intelligence to be a sub-population that did not
breed with the rest of humanity' \- which is increasingly what is happening
with people of high ability & potential income of both sexes attending the
same universities and mating. This polarization has been documented.

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civilian
It's not even that mating like that is increasingly happening--- it's been
that way in nobility for a long time.

What is the True Rate of Social Mobility in Sweden? A Surname Analysis,
1700-2012
[http://www.econ.ucdavis.edu/faculty/gclark/papers/Sweden%202...](http://www.econ.ucdavis.edu/faculty/gclark/papers/Sweden%202012%20AUG.pdf)

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amag
Skimmed through that one a bit.. I think he misses that having a patronym
surname (ending with son) is very much out of fashion in Sweden today (and has
been for quite some time), so people change it. The people most likely to
change it are probably found in the more "elite" professions the author lists.
If you're a blue-collar it may feel a bit presumptuous to change your surname,
you will be ridiculed by your coworkers. OTOH if you're an attorney, it's
almost mandated, "no one" will trust you if you have a patronym surname.

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civilian
Good point, but I believe he addresses that:

 _> One thing we have to be wary of in this calculation of persistence is
surname changing. If people going to the university born with the surname
Anderson were changing this to Wigonius, then there would appear more
persistence than there really was. The biographical sources for some of the
student nations at Lund and Uppsala, Blekingska, Göteborgs, Skånska,
Smålands, and Vermlands at Lund, and Östgöta at Uppsala, allow us to estimate
the fraction of Latinized surnames which were newly adopted in each generation
at the universities, since it gives fathers’ and mothers’ surnames for most
students also. Figure 19 shows what fraction of students in each generation
inherited rather than adopted a Latinized surname.18 For the earlier
generations, 1730-1819, 96% of students acquired the name by inheritance from
their father. However, 1820-1909 that proportion fell to 88%, even though by
design these are all surnames that first existed before 1730.19 This will bias
upwards my estimate of b, but can be corrected for by calculating for each
period a b based just on the relative representation of the surname among the
inheritors in that period._

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

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jm_l
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.

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btilly
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.

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idanoeman
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.

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aklemm
What if being retarded and being highly intelligent aren't ends of the same
spectrum? High intelligence seems much more situational than being retarded. A
retardation is fairly objective and would stand out in almost any scenario,
whereas high intelligence can be invisible when the subject isn't taking an IQ
test.

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sygma
Saw it on your monthly newsletter today. Thanks for compiling those!

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josephjrobison
Was hoping that thinking positively would help increase your own intelligence
- seems to not be that way?

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munchbunny
Maybe not your intelligence. But this article is just about intelligence as a
trait, not about how to live.

The question you ask for yourself is "how do I live well?"

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throwawayaway
So time for GATTACA right?

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hyperion2010
Actually not time for GATTACA because you'd have to tweak 1000s of genes not
one. Which was the finding of this paper.

