MadSci Network: Genetics

Re: Is there a way to change the DNA that we now have permantly?

Date: Fri Apr 13 18:19:24 2001
Posted By: Joshua Chai, Medical student, Medical Sciences, University of Cambridge
Area of science: Genetics
ID: 982014507.Ge

Hi Nezos, I think your question is the “dream” of million people!:-) 
Intelligence has been of interest of both developmental neurobiologists 
and psychologists for many decades. One important aspect of studying 
intelligence is that it is often very difficult to evaluate 
the “intelligence” of people subjects. Obviously a practical solution to 
this is to device some sort of tests and then to make some score about 
intelligence. Hence the invention of the Stanford-Binet test, Wechsler 
test, Raven’s Matrices, etc. and the score “IQ”. But do IQ test really 
measure intelligence? Some IQ testers have argued that if IQ is 
genetically determined, then IQ must represent some sort of measure of 
innate ability. Twin concordance studies and other related studies 
comparing IQ of adopted children, their adoptive parents and their 
biological parents have indicated that, while heritability of IQ is 
probably greater than zero, it does NOT necessarily mean that IQ tests 
measure any “innate abilities”. Moreover, IQ tests have long been 
criticised for being unreliable and unrepresentative. So in the light of 
all these, there still have not been any really reliable test to measure 
intelligence, hence I would doubt anybody can claim that our kids will be 
more intelligent, etc.

Evolutionists will of course argue the other way, claiming that as nature 
chooses the “fittest” to survive, natural selection must have put on 
selective pressure in favour of the more intelligent people. However, one 
must pay attention to the fact that selective pressure in the nowadays 
modern population is much much less than it used to be when people are 
gathering fruits or hunting animals for obvious reasons. In addition, even 
if people are becoming more intelligent, this does not mean that we can 
MAKE ourselves (or our kids) more intelligent in anyway, Nature does it, 
not us! From a biologist point of view, as our society becomes wealthier, 
people’s diet and education both improved dramatically over the last few 
decades, it is not surprising that people nowadays can “perform” better in 
those IQ tests, but it could as well be merely that our education system 
tends to emphasise and train our students to perform well in the areas 
that IQ tests rely on.

Concerning your question about DNA/genetic modification, it is now 
possible experimentally to introduce new genes into a zygote so, apart 
from the ethical aspect, I cannot see why we cannot “modify” our next 
generation’s genome. Nevertheless, importantly, intelligence is NOT 
controlled by any single gene, it is polygenic (controlled by many genes) 
so it is virtually impossible to pin down all those related genes using 
present technology. As to the second part of your question, it is possible 
to change the DNA of some cells relatively “permanently”, and this is the 
central idea about gene therapy, e.g. introducing the gene for chloride 
channels back to the cells lining the respiratory epithelium of patients 
with cystic fibrosis using adenoviruses. However, intelligence is 
obviously controlled by our brain and involves billions of neurones wired 
up in a way even more complex than any maze you can imagine, so if we are 
already born, with our brain more or less developed, I don’t see any 
possibility to change the DNA of all the neurones in one’s brain to make 
oneself any smarter, at least not in the near future!  :-)

Joshua Chai
Medical Student
University of Cambridge, UK

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