Intelligence is in the genes, researchers report

**European blood** · 08-11-2011, 12:22 PM

Intelligence is in the genes, researchers reported Tuesday in the journal Molecular Psychology.

The international team, led by Ian Deary of the University of Edinburgh in Scotland and Peter Visscher of the Queensland Institute of Medical Research in Brisbane, Australia, compared the DNA of more than 3,500 people, middle aged and older, who also had taken intelligence tests. They calculated that more than 40% of the differences in intelligence among test subjects was associated with genetic variation.

The genome-wide association study, as such broad-sweep genetic studies are known, suggested that humans inherit much of their smarts, and a large number of genes are involved.

Booster Shots asked Deary to answer a few questions about the research. The following is an edited version of our questions and his emailed responses.

What exactly were you looking for when you looked at test subjects' genetic information?

We studied over 3,500 people. We looked at over 500,000 individual locations on the chromosomal DNA where people are known to differ. We looked at the association between those DNA differences and two types of intelligence. One type of intelligence was on-the-spot thinking (fluid intelligence) and the other was vocabulary (crystallized intelligence).

You wrote in your paper that 40% of the variation in crystallized intelligence and 51% of the variation in fluid intelligence is associated with genetic differences. How did you calculate those figures? And where does the rest of intelligence come from? Other genes, or environmental factors?

To estimate the proportion of variance associated with common genetic differences (in what are called single nucleotide polymorphisms, or SNPs) we used a new genetic statistics procedure invented by Professor Visscher and his colleagues in Brisbane, called GCTA. The rest of people's differences in those types of intelligence could come from genetic differences we were not able to capture, or from the environment.

Certainly, twin and adoption studies tell us that the environment makes an important contribution to intelligence differences throughout life, and especially in early childhood.

Is this the first time such a study has been attempted? How have scientists studied the relationship between genes and intelligence in the past?

There have been some studies looking at individual genes and sets of genes. And some smaller studies have been conducted with coarser genetic sweeps. This is the first study to use thousands of people, half a million genetic variants and to apply this new GCTA procedure to
estimate the genetic contribution directly from the genes.

Why would it be surprising that intelligence is an inherited trait? Many people might say this seems obvious.

It is not surprising to find that intelligence differences have some genetic foundation. Twin and adoption studies have been suggesting that for decades. But those studies make assumptions -- for example that the environment is just as similar for non-identical twins as for identical twins -- and people have questioned those assumptions.

Here, we bypass all that and test the DNA. What is not at all obvious is what the genetic contribution is. From our results, we can suggest that a substantial amount of the genetic contribution to intelligence differences comes from many, many small effects from genetic variants that are in linked with common variants (SNPs).

What parts of your study and analysis do you suspect might receive criticism, and on what grounds?

We don't point to individual genes among the 40%-50% of the variance we detected. We need far larger numbers to do that. We know now that it would be better to have ten times or more subjects than we tested.

We did not have exactly the same intelligence tests in each sample, so that might have led us to underestimate some effects. The GCTA procedure is not easy to understand, so it is hard for people to get their head round how the estimate for the genetic contribution is derived.

http://www.latimes.com/health/booste...,3811470.story

**~~Aces High~~** · 08-11-2011, 12:25 PM

By the look of that colour chart,obviousley not in black genes.

**Oreka Bailoak** · 08-11-2011, 12:51 PM

40% of the variation in crystallized intelligence and 51% of the variation in fluid intelligence is associated with genetic differences.

Based on adoption studies, twins raised apart studies, and studies of family members I've seen the correlation between genetics and general intelligence at 70% (G-Factor).
http://en.wikipedia.org/wiki/General...ligence_factor

I've also seen studies that show that general intelligence is not as changing as we'd like to think. For example 99% of people cannot raise their IQ above 15 points and a very high percentage cannot raise their IQ above 7 points. As well as many other tests of intelligence g-factor tests.

The book "The Blank Slate" does a good job showing the social ramifications of learning that everyone's mind is not as capable as we'd like to think. This has huge changes for school structure, school funding, expectations of others, even parenting expectations and crime.
http://www.amazon.com/Blank-Slate-Mo.../dp/0670031518

And I'd like to point out that an IQ below 70 is considered mildly retarded. But there is quite a bit of intelligence variance within each race.

And also 4% of people lack conscious minds. I think this is incredibly important to understand as I've known many people like this and they will skrew you over.
http://www.amazon.com/Sociopath-Next...3066864&sr=1-1

**Frederick** · 08-12-2011, 04:58 AM

This is a map I made from these numbers:
http://www.rlynn.co.uk/pages/article...ligence/t4.asp

Only limited to Europe and only to the "tested" numbers, not the "guessed" ones.

And this is a list from another study:
(someone posted this in another thread but I recall exactly these numbers from an article in a newspaper.

it agrees on the same "effect" of highest European IQ grades beeing on a NOrth to South line (Sweden to Italy), right in the middle of Europe.

Both aswell agree on the Poles beeing the most intelligent "Slavs", but on a different level. (second posted study actually puts the Poles very close to the topranking Dutch and Germans.

**Groenewolf** · 08-12-2011, 05:06 AM

This is pretty much old news for everyone who is familiar with the so called London School, even if they do not know that term. The pure nurture side is practically filled with scientists who do not research intelligence and policy makers.

**Gamera** · 08-12-2011, 05:19 AM

The Southern Cone is the most intelligent in South America, I wonder why...

**boogeyman** · 08-12-2011, 05:43 AM

South-east Europe is a bit stupid according to this data. Perhaps it is because of larger rural population which tends to have lower IQ than urban population.