Genetics and intelligence differences: five special findings

http://www.nature.com/mp/journal/vaop/ncurrent/full/mp2014105a.html

by tokenadult • 12 years ago

91 81 12 years ago

spindritf• 12 years ago

Plominism: The Christian heresy that salvation is neither by faith nor by works, but 50% hereditary and 50% based on non-shared environment

https://twitter.com/slatestarcodex/status/500107441762074625

gliese13372• 12 years ago

You can probably guess it from context, but I had to look this up to be sure, so for the benefit of others: assortative mating is when you have kids with other people similar to you, rather than selecting mates randomly. In other words, in this case, people with high intelligence tend to marry other people with high intelligence, and people with low intelligence marry other people with low intelligence. This causes the variance in the distribution of intelligence to steadily increase, rather than everybody evening out over a few generations.

phkahler2• 12 years ago

And if a society values intelligence, they should encourage smarter people to reproduce and offer as much birth control as possible to less smart people. Following this line of reasoning and policy is sure to ignite all kinds of flame wars ;-)

fizixer• 12 years ago

And it sure did ignite flame wars and the topic is not openly pursued anymore in scientific circles, regardless of how objective it might be.

Luckily we don't have to go there. Technology is going to be the great equalizer, and might end up offering you off-the-shelf intelligence upgrade (I'm talking about a time-frame of next 30-80 years).

ArkyBeagle4• 12 years ago

It's called eugenics and it's very bad. At the very least it suffers from this self-referential craziness that nearly guarantees bad results.

People are economically unproductive because the economy slowly gets more and more hostile to more and more people. Tyler Cowan and others call this problem "Zero Marginal Product Workers".

jiggy20117• 12 years ago

The problem is that smart people tend to earn more, thus the children tend to cost them more both in terms of opportunity cost (hours away from work) and actual cost (more likely to consider things like private school as essential). To incentive them you would need to start giving already wealthy people quite significant tax breaks etc.

tjradcliffe• 12 years ago

There is an interesting and much-neglected corollary to the heritability of intelligence, which is that we are part of the least intelligent generation of humanity that has ever lived.

This follows from the two conditions:

1) intelligence is at least somewhat heritable (empirically true, according to the article)

and

2) intelligence is positively correlated with reproductive success (plausible give humans seem to have been selected for it)

The conclusion follows from the way world population has exploded in the past 250 years, increasing roughly ten-fold in twenty or twenty-five generations. That increase equates to "zero selective pressure": basically anybody could breed successfully, and they did (including my ancestors, some of whom occupied the more stagnant and brackish depths of the gene pool...)

So up until 1750 or so intelligence was being selected for, generation after generation. After that time, there was no pressure and the many small effects that this article documents as underlying the heritability of intelligence (with no single gene showing as much as a 1% effect on the overall outcome) would happily carry us all on a random walk across the landscape, creating engineers in some parts and political partisans in others.

This realization makes particularly funny the various organizations that have at times promoted Nobelists etc as pinnacles of intelligence (William Shockly, inventor of the transistor, was heavily involved in this kind of thing). Nobelists are certainly bright, but it seems more likely you'd find the most intelligent people amongst still-extant stone age tribes, whose pre-industrial life-style would still subject them to selective pressures long released in the more-developed world.

eastbayjake3• 12 years ago

Assortative mating -- among other things -- was one of the "problems" identified by Charles Murray in his book Coming Apart as a cause of greater inequality in American society[1]. As people "stick to their own kind", there are fewer opportunities for both economic and cognitive mobility: in the past, when marriage was determined by other factors, it was more likely that a highly intelligent person might have children with a much less intelligent person. That's increasingly no longer the case.

[1] http://www.nytimes.com/2012/02/12/books/review/charles-murra...

matoffk• 12 years ago

Interesting, but assortative mating is not a new phenomenon in the history of mankind. If anything, its impact has probably decreased significantly over the past centuries and decades. This makes it more difficult to take such explanations for growing income inequality at face value.

sfbsfbsfb5• 12 years ago

I first saw this concept in the context of intelligence in "The Bell Curve" by Richard J. Herrnstein and Charles Murray (1996). They suggested the process is accelerating dramatically with development of situations that make it easier for intelligent people to find each other: the movement of the population from the farm to cities, higher education, improved communications and less restricted travel. I would not be surprised if online dating sites are also playing a role. Once you start thinking about this in the context of genetics, matings and the potential for a survival advantage and increased quality of life leading to further segregation you wonder if this does not have the potential to eventually result in the development of a new species?! I would be interesting to know if the IQ "density" is significantly altered in certain communities in northern California, Boston, NY, etc. associated with industries selecting for high IQ workers. [Edit]Just amused myself thinking of the Silicon Valley crew as participants in a breeding experiment.

gliese13372• 12 years ago

Having now learned the terminology, assortative mating could indeed lead to speciation in the general case; it's just a special case of sexual selection. I find it highly unlikely that that will happen with human intelligence, though (despite the fact that it's been used in fiction more than once). The reason is that there's a limit to how big the variance can get- it doesn't grow forever, it grows until limited by other factors (i.e., there are only so many intelligence-promoting alleles that you can possibly have).

It would take intentional segregation to cut off all gene flow between the upper and lower halves of the intelligence Bell curve, thus allowing other differences to pile up between the populations, to cause speciation. And as noted elsethread, that's called eugenics and generally frowned upon in polite society.

jacquesm6• 12 years ago

Species are not 'developed'. They come into being because of isolation and sufficient time passing.

Even all the breeding done with dogs has not resulted in speciation.

The time scales are vast and the degree of separation that a barrier such as 'intelligence' (for whatever definition you wish to employ) will provide will be insufficient to cause this to happen.

No Elois and Morlocks in our future through that avenue.

Think about it: if geographic separation and very long spans of time have not been enough then why would a mere trait be enough, we have plenty of examples of the former.

gonehome2• 12 years ago

I would suspect that physical looks/features would throw a wrench into this - or at least correct things a bit.

trhway• 12 years ago

yep, until gap becomes too big so the species divergence begins as physical looks/features play role for both processes - help keep a species together as well as to help distinguish between subspecies once the divergence has started thus speeding up the divergence.

peripitea• 12 years ago

I don't follow. How would that affect this phenomenon? Given that the cited correlation refers strictly to intelligence, looks (and for that matter, all other factors) are presumably already accounted for.

cle• 12 years ago

From a cursory glance at this post, I don't see how your conclusion follows. I'd believe it if I saw the model and some data that supports it. It depends on how populations along the intelligence distribution reproduce, and what the variance of intelligence is of offspring along the continuum. If everyone reproduces at the same rate, and the intelligence variance of offspring is constant across the population, then I would expect the intelligence distribution of the overall population to remain the same. It seems like, given those constraints (which may or may not be true), the variance would remain the same--neither evening out nor diverging.

Let me know if I'm mistaken...honestly I've only read part of the article and I only have a lay understanding of this stuff.

tormeh• 12 years ago

It's kind of trite and obvious by now, but can we please kill the "Everyone gets what they deserve" line of thinking?

arethuza• 12 years ago

The idea that "they deserve whatever they can get" is one of the criticisms of modern UK/US culture made by Michael Young who actually coined the term in his satirical book The Rise of the Meritocracy:

http://www.theguardian.com/politics/2001/jun/29/comment

[Edit: I don't know about the US but here in the UK it is fairly common to define "merit" in ways that don't actually seem to include "performance" - though I think this is a far bigger problem in the public sector than the private].

roywiggins• 12 years ago

This is basically the "just world" fallacy writ large, right?

FD3SA• 12 years ago

I never understood why the politically correct crowd happily accepts that athletic ability is heritable, yet when it comes to intelligence suddenly all bets are off.

As soon as we accept reality for what it is, we can begin adapting our societies and policies to maximize opportunities for individuals with the knowledge that our talents and limitations vary quite drastically.

hackuser6• 12 years ago

the politically correct crowd happily accepts ...

I don't think I've heard anyone serious say that there was no heredity of intelligence. Could you be more specific about who says what? Perhaps you are writing quickly, but these are imaginary statements from imaginary people.

phkahler2• 12 years ago

> I never understood why the politically correct crowd happily accepts that athletic ability is heritable, yet when it comes to intelligence suddenly all bets are off.

Because athletic ability is more recreational - you can say different people are good at sports, music, art, etc... there are nice alternatives. But it's not PC to imply anyone is inherently stupid. I phrase it that way because saying "inherently smarter" is OK on the surface, but the corollary is that someone else is inherently less smart. Being "PC" is all about not offending anyone.

sliverstorm• 12 years ago

The implications of intelligence are more touchy.

Outside of professional athletes, being good at soccer is not much more important than having blue eyes.

Intelligence, on the other hand, is an underpinning of modern life.

The only reason we acknowledge the heritability of wealth, another underpinning, is because it is by far too obvious to deny.

(Quite the reversal from the origin of the species!)

thenmar• 12 years ago

Would you mind elaborating on what you mean by "the politically correct crowd"?

ArkyBeagle4• 12 years ago

Intelligence as a general topic is pretty hard for me to swallow. A lot of "intelligence" that we can test for is mathematical in nature and that can be learned. I'm pretty sure I could teach multiple-choice test taking.

Intelligence, I think, can broadly be defined as "the ability to score well on intelligence tests." The most common is supposedly correlated with freshman college survival. History is full of people who were considered "dull" as students but later shook the world in a way that means they had significant intellect.

It wouldn't be a problem except we sort people into piles and this is yet another sorting mechanism.

jiggy20117• 12 years ago

I'm not aware of any generalised test of athletic ability. The traits that make one good at archery will be different from those that make one a good sprinter. With intelligence we attempt to collapse it all down to one number and rate people as smart or dumb as a single metric.

lambdaphage5• 12 years ago

Two points about this. First, a consensus developed over more than a hundred years of study requires a little more than an off-handed dismissal-- do you understand _why_ a general factor of intelligence is acknowledged by practically everyone who has studied the issue, or why it is impossible to devise a test that purports to measure cognitive ability but varies independently of that general factor?

Secondly, I gladly accept your reductio of a "general factor of fitness". If you restrict yourself to the range of world-class athletes, I grant that performance in archery will correlate negatively with performance in sprinting. This is just Berkson's paradox, or the "restriction of range" phenomenon. If you consider the entire population, however, I would be very surprised if a "general factor of fitness" didn't fall right out of a battery of athletic tests. In general, people who are faster than average will also be stronger than average and probably more dextrous too, and it makes sense to call that factor "physical fitness".

barrkel• 12 years ago

Conversations about it often don't go well.

All to often, people start using it as justification for income disparity, wealth disparity, minority crime rates and sometimes differences in economic development between different countries. Racism and classism aren't too far behind.

I'm reminded that it is no more noble to fool a person out of his money by outwitting him, than it is to bully him out of his money with superior strength. Being smarter isn't necessarily a moral justification for greater rewards.

Similarly, we rely on the economic system using prices as an information signalling mechanism; more valuable labour is priced up, and thus supply should follow. But if the valued labour is intelligent labour, and its supply is not easily increased, then there is less of a moral case for paying its suppliers more, for that attribute alone.

jiggy20117• 12 years ago

Although assuming it was true that intelligence was mostly based on genetics rather than quality of education (I don't have a strong view one way or the other) then we could use that knowledge to improve wealth inequality by filtering people into school systems with very different curriculum where they would learn the best way to add value with their ability level.

ap222132• 12 years ago

It's not that I don't believe that intelligence is heritable. I do. It's more that I don't believe that it's all that important to be intelligent in order to be a good Human.

People have a natural attraction to those similar to them. In history, the over-emphasis of particular and possibly unimportant (who knows?) traits has often been the cause for wars, genocides and all sorts of other evils.

Further, I don't think that relative Human intelligence has all that much magnitude. That is - a 'really intelligent' Human is not all that different from a 'non-intelligent' one, taken in the context of other species. And, those non-intelligent ones may have particularly interesting genetics that make them important to the species, in other ways.

Humans have done pretty well as a species with lots of diversity. Why ruin a good thing? And, do you really want Humanity to be comprised of near clones?

jiggy20117• 12 years ago

Probably because the jobs traditionally done by the less intelligent are being shipped overseas or done by machines leaving these people in poor economic circumstances. Intelligent people would not have to be clones, smart people can be quite different from each other in terms of personality, areas of interest etc.

hackuser6• 12 years ago

Would someone decode what Nature means by "open" and "expert review"? What is "open" about it? Is this settled science, one person's hypothesis, or something in between?

w1ntermute• 12 years ago

1. Open = free (no subscription required)

2. Expert review = exactly what it sounds like (as opposed to original research)

3. Something in-between

hackuser6• 12 years ago

> Is this settled science, one person's hypothesis, or something in between?
3. Something in-between

Much appreciated (all of your answers). If someone has knowledge of where this falls on the continuum of #3, it would help those of us outside the field understand how much credibility we should give to this article.

gwern• 12 years ago

Is it really 'something in-between'? This is https://en.wikipedia.org/wiki/Robert_Plomin - if there's a greater living behavioral geneticist, his name escapes me.

socialist_coder• 12 years ago

So, it seems to follow that one could take a bunch of fertilized embryos, measure the genome-wide polygenic score (GPS) of each embryo, then select only the best one.

The only thing missing is that the genome-wide polygenic score (GPS) for intelligence has yet to be discovered.

Unfortunately, even when something like this is possible, it would probably be made illegal even though it would surely be a positive thing for humanity.

vince_refiti3• 12 years ago

Q: What is intelligence? A: Thing that is measured with intelligence tests.

Q: What are intelligence tests? A: Things that measure intelligence.

lambdaphage5• 12 years ago

This pair of rhetorical questions actually has a non-rhetorical answer, and it is far more interesting (though less precious) than the one implied here.

This being the internet, the serious answer is a mouseclick away: http://en.wikipedia.org/wiki/G_factor_%28psychometrics%29

vince_refiti3• 12 years ago

It is more correctly circular reasoning. The psychometric measure g does not break this circle at all. I will never believe in "intelligence tests" until this circular reasoning can be broken.

tokenadult• 12 years ago

Thanks for the interesting comments posted while I was watching my sons play soccer this evening. To answer some questions that came up in various subthreads, yes, both Robert Plomin and Ian Deary are mainstream researchers on the behavior genetics of human intelligence, the authors of well regarded textbooks (Plomin), popular books (both), and primary research articles (both) on various related topics. Their joint point of view as expressed in the review article published today is not the exact point of view of all researchers in the field, but I thought it would do as a discussion-starter here on Hacker News.

A crucial detail (Deary and Plomin would both agree about this, but it hasn't come up in the discussion here yet) is that heritablity has NOTHING to do with modifiability. It is quite possible in principle that a novel environmental intervention might be discovered that could boost most people's intelligence. It is even possible that the most effective intervention might have a gene-environment (G × E) interaction such that the intervention would most help people with lowest IQ, and least help people who already have high IQs. No such intervention that human beings can direct purposefully has yet been found, but it is clear from the Flynn effect[1] that something in the environment can have powerful effects in raising average IQ levels of whole countries, as has happened in the developed world throughout the last century (for as long as IQ tests have been around).

It is correct that people marry and have children on bases other than just shared level of intelligence. (But living in the same town, and completing higher education at similar ages, and pursuing compatible occupations for marriage, etc. is correlated with IQ.) It is still far too early to say how rapidly human populations might see noticeable effects from assortative mating by IQ. It is reasonably clear that often-feared dysenic trends probably are NOT happening--the lowest-IQ people in the world population don't reproduce at all, and high-IQ people actually have reasonable numbers of children to replicate their genes. In any event, the favorable environmental trends have SWAMPED whatever genetic trends are going on for IQ in the whole human population, and people are getting smarter all over the world, according to the research on the Flynn effect.

It is still a hard problem to identify anything at all meaningful and replicable about how gene differences influence IQ differences, even though it is now settled wisdom that they do. Human IQ, as the article says, is influenced by MANY genes, and many of those genes interact with one another in ways that are not understood at all yet.

[1] https://www.ted.com/talks/james_flynn_why_our_iq_levels_are_...

http://blog.ted.com/2013/09/26/further-reading-on-the-flynn-...

Genetics and intelligence differences: five special findings

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