1. A study that is sensitive to rare variants which are implicated in schizophrenia risk has been completed. These rare variants add to the heritability already associated with common variants, estimated to be at least 32%.
2. In related work, mutations affecting schizophrenia risk were shown to depress IQ in individuals who did not present for schizophrenia.
A genome-wide association study (GWAS) of educational attainment was conducted in a discovery sample of 101,069 individuals and a replication sample of 25,490. Three independent single-nucleotide polymorphisms (SNPs) are genome-wide significant (rs9320913, rs11584700, rs4851266), and all three replicate. Estimated effects sizes are small (coefficient of determination R2 ≈ 0.02%), approximately 1 month of schooling per allele. A linear polygenic score from all measured SNPs accounts for ≈2% of the variance in both educational attainment and cognitive function. Genes in the region of the loci have previously been associated with health, cognitive, and central nervous system phenotypes, and bioinformatics analyses suggest the involvement of the anterior caudate nucleus. These findings provide promising candidate SNPs for follow-up work, and our effect size estimates can anchor power analyses in social-science genetics.
Steve’s Hsu guess is that most intelligence alleles have negative effect. That is, the majority of genetic variation in cognitive ability is determined by the number and type of somewhat deleterious mutations we all carry around. (There are probably also minor alleles of positive effect, but fewer of them.) Note the CNVs in this article, while having a significantly (1 SD) negative effect on IQ, do not prevent reproduction (fecundity is reduced, but not to zero), so clearly mutations of large effect can linger for some generations. Mutations of smaller effect might even be neutral due to pleiotropy, etc.
According to Steve Hsu’s estimates (based on actual data) most humans have (order of magnitude) 1000 rare (-) alleles for intelligence and height, and someone who is one standard deviation above average has (very roughly) 30 fewer (-) variants. A human with none of the negative alleles might be 30 SD above average! Such a person has yet to exist in human history…
When current IQ tests were developed, the median raw score of the norming sample is defined as IQ 100 and scores each standard deviation (SD) up or down are defined as 15 IQ points greater or less, although this was not always so historically. By this definition, approximately 95 percent of the population scores an IQ between 70 and 130, which is within two standard deviations of the mean.
30 SD above average would be and IQ of 550.
Crispr, RNA targeted gene therapy, was used to genetically modify monkeys. If human embryos were modified and if all intelligence intelligence related genes are identified and if Steve Hsu’s theory of intelligence is correct then such IQs of approximately 550 could be possible for fully genetically modified people.
SOURCES – Information Processing (Steve Hsu’s site), Wikipedia, Journal Science
Brian Wang is a Futurist Thought Leader and a popular Science blogger with 1 million readers per month. His blog Nextbigfuture.com is ranked #1 Science News Blog. It covers many disruptive technology and trends including Space, Robotics, Artificial Intelligence, Medicine, Anti-aging Biotechnology, and Nanotechnology.
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