Questionnaire Papers Genetic and Environmental Influences on the Development of Intelligence Measures of intelligence were collected in 209 twin pairs at 5, 7, 10, and 12 years of age, as part of a longitudinal project on intelligence, brain function, and behavioral problems. Intelligence was measured at 5, 7, and 10 years of age with the RAKIT, a well-known Dutch intelligence test, consisting of 6 subscales. At 12 years of age, the complete WISC-R was administered (12 subscales). Both intelligence tests resulted in a measure of full-scale IQ (FSIQ). Participation rate is around 93% at age 12. New scientist Environmental Genetic Research reveals genetic link to human intelligence 09 Aug 2011 University of Manchester scientists, working with colleagues in Edinburgh and Australia, have provided the first direct biological evidence for a genetic contribution to people’s intelligence. Previous studies on twins and adopted people suggested that there is a substantial genetic contribution to thinking skills, but this new study – published in the journal Molecular Psychiatry – is the first to find a genetic contribution by testing people’s DNA for genetic variations. The team studied two types of intelligence in more than 3,500 people from Edinburgh, Aberdeen, Newcastle and Manchester. The study examined more than half a million genetic markers on every person in the study. “The study confirms the earlier findings of the research in twins. “We can now use the findings to better understand how these genes interact with each other and the environment, which has an equally significant contribution. Ends Notes for editors A copy of the paper is available on request.
Heritability of IQ Research on heritability of IQ infers from the similarity of IQ in closely related persons the proportion of variance of IQ among individuals in a study population that is associated with genetic variation within that population. This provides a maximum estimate of genetic versus environmental influence for phenotypic variation in IQ in that population. "Heritability", in this sense, "refers to the genetic contribution to variance within a population and in a specific environment".[1] There has been significant controversy in the academic community about the heritability of IQ since research on the issue began in the late nineteenth century.[2] Intelligence is a polygenic trait under normal circumstances according to recent research. Heritability and caveats[edit] Caveats[edit] There are a number of points to consider when interpreting heritability: Estimates of the heritability of IQ[edit] Shared family environment[edit] Non-shared family environment and environment outside the family[edit]
Research reveals genetic link to human intelligence University of Manchester scientists, working with colleagues in Edinburgh and Australia, have provided the first direct biological evidence for a genetic contribution to people's intelligence. Previous studies on twins and adopted people suggested that there is a substantial genetic contribution to thinking skills, but this new study -- published in the journal Molecular Psychiatry -- is the first to find a genetic contribution by testing people's DNA for genetic variations. The team studied two types of intelligence in more than 3,500 people from Edinburgh, Aberdeen, Newcastle and Manchester. The paper, by Dr Neil Pendleton and colleagues, found that 40% to 50% of people's differences in these abilities could be traced to genetic differences. The study examined more than half a million genetic markers on every person in the study. The new findings were made possible using a new type of analysis invented by Professor Peter Visscher and colleagues in Brisbane.
Intelligence changes 'driven by evironment' Thursday January 19 2012 The results of the study remain uncertain The Daily Mail has reported that “lifestyle is key to staying alert into old age”, and that genes are not to blame for changes in intelligence as we age. This news is based on an unusual long-term study that examined how a group of nearly 2,000 Scottish people varied in intelligence across the course of their lives, and whether genetic and environmental factors could be responsible. This research combined relatively new genetic technology with a long-term study of intelligence. Where did the story come from? The study was carried out by researchers from the Universities of Edinburgh and Aberdeen, along with other institutes throughout the UK and Australia. What kind of research was this? This was a genome-wide association study that looked for links between genetic variation and changes in intelligence among members of a long-running cohort study in Scotland. What did the research involve? What were the basic results?
Effects of Heredity and Environment on Intelligence It is often difficult to separate the relative influences of heredity and environment on human characteristics. People who have similar genetic makeup (e.g., brothers and sisters, parents and their children) typically live in similar environments as well. So when we see similarities in IQ among members of the same family, it is hard to know whether those similarities are due to the genes or to the environments that family members share. Evidence for Hereditary Influences Earlier we mentioned that measures of information processing speed correlate with IQ scores. Twin studies Numerous studies have used monozygotic (identical) twins and dizygotic (fraternal) twins to get a sense of how strongly heredity affects IQ. Most twins are raised together by the same parent(s) and in the same home, and so they share similar environments as well as similar genes. The correlation of .72 indicates that identical twins raised in different environments tend to have very similar IQ scores. Notes
» Genetics Largely Underlies Intelligence to School Acheivement Link : Home – Child Mental Health Blog : University of Vermont While the genetic influence on intelligence has been well studied, less is known about school achievement and the genetic/environmental links between intelligence and school achievement. Previous work has also struggled with potential measurement and sampling bias. This study used national data from large Dutch and English samples to address some of these concerns. The total sample included nearly 174,000 11 year old children in England and 166,000 children in the Netherlands. Intelligence was measured using the Cognitive Ability Test for the English sample while achievement was assessed through schools’ standard school performance tests. Intelligence assessment for the Dutch sample of children ages 8, 10, and 12 came from two tests of nonverbal intelligence while school achievement was measured using scores on arithmetic and language. In the English dataset, the heritability of intelligence was found to be high at 70%. Reference Calvin CM, et al.
Intelligence and IQ Intelligence and IQ Dr. C. George BoereeShippensburg University Intelligence is a person's capacity to (1) acquire knowledge (i.e. learn and understand), (2) apply knowledge (solve problems), and (3) engage in abstract reasoning. Intelligence Quotient (IQ) is the score you get on an intelligence test. Under 70 [mentally retarded] -- 2.2% 70-80 [borderline retarded] -- 6.7% 80-90 [low average] -- 16.1% 90-110 [average] -- 50% 110-120 [high average] -- 16.1% 120-130 [superior] -- 6.7% Over 130 [very superior] -- 2.2% Descriptive statistics To understand IQ and the research involving IQ, we need to understand the basics of descriptive statistics: 1. 2. 3. To understand the next discussion, we need to know about correlation. A perfect correlation is +1. Perfect correlation can also be -1. Most things have a correlation of 0. In psychology, we are generally impressed by correlations of .3 and higher. .8 or .9 blows us away. But one thing correlation cannot tell you is what causes what. 1.
Best evidence yet that a single gene can affect IQ - health - 16 April 2012 A massive genetics study relying on MRI brain scans and DNA samples from over 20,000 people has revealed what is claimed as the biggest effect yet of a single gene on intelligence – although the effect is small. There is little dispute that genetics accounts for a large amount of the variation in people's intelligence, but studies have consistently failed to find any single genes that have a substantial impact. Instead, researchers typically find that hundreds of genes contribute. Following a brain study on an unprecedented scale, an international collaboration has now managed to tease out a single gene that does have a measurable effect on intelligence. "It seems like the biggest single-gene impact we know of that affects IQ," says Paul Thompson of the University of California, Los Angeles, who led the collaboration of 207 researchers. Two teaspoons The variant is in a gene called HMGA2, which has previously been linked with people's height. "C is the good one," says Thompson. Brain ager