Professor Steve Hsu has given a Google Tech Talk on human intelligence (presentation in 2011). Steve has worked with the BGI(Beijing Genomics Institute). BGI has been sequencing over 2000 people with an IQ over 160 and 4000 people with an average IQ distribution (controls). The project is trying to determine the exact genetic components of intelligence.
Intelligence is as inheritable as height
Intelligence is broadly 80% inherited and 60% for positive inheritance.
The Near Future
Expect full sequencing (not just SNP genotyping) of 100,000 to 1 million individuals within next few years. (BGI reached a rate of 1000 per day in 2012.) Probably paid for by science agencies of national governments. (Total cost roughly US $1billion or so … comparable to first genome sequenced by Human Genome Project.)
If sufficient phenotype data is collected about these individuals, will have very well-powered GWAS (Genome Wide Associative Study) studies within next few years – enough statistical power to capture a good fraction of total additive variance (about .6 for intelligence)
BGI is expected to announce the results of the analysis of sequencing 2000 geniuses and 4000 controls in two months)
The Future: genetic engineering
• Suppose that we can non-destructively sequence gametes (sperm and egg cells).
• We can imagine parents choosing which gametes to unite in order to constitute their offspring.
• In particular, they might choose to unite gametes bearing many g-enhancing alleles.
Suppose that we have 100 g-affecting loci, each with minor allele frequency (MAF) of 0.1 and an average effect of 0.02.
• Instead of using a random sperm cell to conceive, a couple might go through 500 cells and choose the one with the most + alleles.
• If all couples in the population do this, what will happen to the level of g ?
In the offspring generation, the mean level of g will increase by 0.2 SDs (standard deviations, IQ has a mean of 100 and standard deviation of 15. So even the relatively early selection capability would be an increase of 3 IQ points each generation. More complete sequencing to allow for more comprehensive allele selection would increase this).
• Consequences will be especially prominent at the tails
There will be more than twice as many individuals exceeding 4 SDs above the parental mean.
• Recall the accomplishments of the SMPY cohorts. An enrichment of individuals blessed with this potential!
• Since there are hundreds (if not thousands) of manipulable loci, this would be only the beginning ..
Nearer Term Pre-Implantation Screening
In vitro fertilization exists now. It would be possible to economically produce about 10-30 embryos and then to genetically screen them for the alleles. One could use a mathematical analysis to determine the distribution intelligence contributing alleles and then select for the embryo with a favorable genetic distribution.
This would be less effective than screening sperm and egg cells and then combining the best ones.