Genes and intelligence: The 3% solution

9. May 2014

Date: 08-05-2014
Source: The Economist

A potent source of genetic variation in cognitive ability has just been discovered

Genes IntelligencePEOPLE are living longer, which is good. But old age often brings a decline in mental faculties and many researchers are looking for ways to slow or halt such decline. One group doing so is led by Dena Dubal of the University of California, San Francisco, and Lennart Mucke of the Gladstone Institutes, also in San Francisco. Dr Dubal and Dr Mucke have been studying the role in ageing of klotho, a protein encoded by a gene called KL. A particular version of this gene, KL-VS, promotes longevity. One way it does so is by reducing age-related heart disease. Dr Dubal and Dr Mucke wondered if it might have similar powers over age-related cognitive decline.

What they found was startling. KL-VS did not curb decline, but it did boost cognitive faculties regardless of a person’s age by the equivalent of about six IQ points. If this result, just published in Cell Reports, is confirmed, KL-VS will be the most important genetic agent of non-pathological variation in intelligence yet discovered.

Dr Dubal and Dr Mucke made their discovery when they looked at 220 volunteers aged 52 to 85, to study the effects of KL-VS on ageing. They assessed their volunteers’ faculties of memory, attention, visuo-spatial awareness and language. From these, they constructed a composite measure of cognition. Read the rest of this entry »

Human intelligence: Cleverer still

20. December 2012

Date: 19-12-2012
Source: The Economist

Geniuses are getting brighter. And at genius levels of IQ, girls are not as far behind boys as they used to be

SCIENCE has few more controversial topics than human intelligence—in particular, whether variations in it are a result of nature or nurture, and especially whether such variations differ between the sexes. The mines in this field can blow up an entire career, as Larry Summers found out in 2005 when he spoke of the hypothesis that the mathematical aptitude needed for physics and engineering, as well as for maths itself, is innately rarer in women than in men. He resigned as president of Harvard University shortly afterwards.

It is bold, therefore, of Jonathan Wai, Martha Putallaz and Matthew Makel, of Duke University in North Carolina, to enter the fray with a paper that addresses both questions. In this paper, just published in Current Directions in Psychological Science, they describe how they sifted through nearly three decades of standardised tests administered to American high-school students to see what had been happening to the country’s brightest sparks.

They draw two conclusions. One is that a phenomenon called the Flynn effect (which weighs on the “nurture” side of the scales because it describes how IQ scores in general have been rising over the decades) applies in particular to the brightest of the bright. The other is that part, but not all, of the historic difference between the brainiest men and women has vanished. Read the rest of this entry »