If we reiterate the definition of ‘intelligence’ as an ability to acquire and apply knowledge and skills, we might recognise that this definition possibly encompasses two distinct aspects of intelligence, first, as an innate ability of a physical human brain and, second, a subsequent ability to acquire knowledge and skills. In this context, even the most naturally intelligent brain would be limited in its ability if denied all access to learn from the world, which is often debated in the form of nature versus nurture. However, we might first introduce aspects of this debate in terms of the next chart.
This chart reflects the correlation of IQ scores, not actual IQ scores, with the relationships between sibling types plus the parent/child relationship. In the first column, we see that identical twins living together have a higher IQ correlation than twins living apart. In the next column, we see that fraternal twins of the same gender have a higher IQ correlation than fraternal twins of opposite gender. In the third column, we see siblings living together have a higher IQ correlation than siblings living apart. Finally, in the last column, we see that children living with their biological parents will have a higher IQ correlation than children living with foster parents. While the following summary is not authoritative, it possibly provides a starting point for discussion.
- In the case of fraternal twin that shared almost identical DNA,
the very high correlation of IQ seems to suggest the importance of their
inherited DNA, which is slightly reduced if these twins are reared apart,
i.e. nature dominates nurture. However, what is not obvious is this
secondary condition is the degree of difference between the two ‘reared
apart’ environments, e.g. first world to third world. While the
innate intelligence of both identical twins might be similar, it is
possible that if one twin was reared in a third world environment, the
acquired knowledge and skills may be severely compromised.
- In the case of the fraternal twins, who may have significantly
different DNA, the correlation of IQ is much lower, which is slightly
further reduced, if the twins are of different gender. Here the IQ difference
between fraternal twins of different gender may simply be reflecting
the general IQ differences between genders previously outlined in the
- In the case of normal sibling, we might question why IQ is any
different to fraternal twins given that both cases imply different DNA
makeup. One possible reason may be linked to the fact that fraternal
twins are identical in age and therefore will probably have very similar
nurturing environments, while normal siblings with a significant age
gap may be subject to differing nurturing environments at home and at
school, although this is just speculation at this stage.
- Finally, in the case of the parent child relationship, the child growing up with natural parent has to some extent inherited aspects of their DNA, while a fostered or adopted child will not. Again, the difference might be suggesting that nature dominates nurture.
Note: The scope of the discussion surrounding IQ correlation with other variables is often predicated on statistical analysis. While this subject is not the focus of this discussion, a section entitled ‘
In essence, the previous chart has defined various correlation coefficients associated with various cognitive abilities, which might be characterised in terms of an IQ score. However, correlation coefficients have to be interpreted with some care for two basic reasons, first, they only infer a statistical relationship between the variables selected and, second, high correlation may not always be linked to a direct causal relationship. In this context, aspects of the nature versus nurture debate are not necessarily conclusive, so while it might reasonably be assumed that genetics plays an important role in inherited intelligence, nurture must still have a role to play in the acquisition of knowledge and skills. While this is not an unreasonable starting position based on the assumption that DNA contains the blueprint for all cells underpinning the development of the human physiology, including the brain, there is still limited knowledge of which combination of genes actually play an active role in inherited intelligence. This position is then possibly complicated by the relatively new field of epigenetics, which appears to suggest that certain genes may be activated and/or deactivated due to environmental factors. However, while it is not practical for this discussion to pursue such detail, the following links to earlier discussions may provide a wider overview.
- Biological Models
- The DNA Model
- The Cellular Model
- The Inheritance Model
- The Epigenetics Model
- The Genetic Model
- The Brain Model
Given the implied complexity surrounding the concept of intelligence, especially if realised in terms of possibly millions of discrete cognitive processes within the human brain, we might question how any deterministic genetic enhancements might ever be made to the brain.
So what is the potential scope of genetic enhancement?
The scope of this question is essentially technical and the focus of previous discussions, e.g. ‘genetic developments’ . However, this discussion is attempting to put this question into some perspective in terms of the implications on future social evolution and while the general idea of enhanced intelligence as a future catalyst of social change is the main focus, we might need to recognise that any enhancement may have unintended consequences. For example, even small improvements in physique, health and aging may all have causal effects on social developments that lead to an increasing stratification of society in terms of ability and potential. However, as previously outlined, we might consider a staged development, where genetic enhancements are first accepted as a treatment for inherited diseases, which is then extended to include other personality traits, e.g. neuroticism, which are known to have some genetic cause. In this context, such genetic enhancements might be perceived as a net benefit to the individual, who might otherwise be afflicted with medical problems, but also by both economic and political institutions that may perceive the same problems in terms of lower productivity and increased welfare costs.
Note: At this point in time, some genetic manipulation of the human genome is possible and considerable research is now focused on genetic treatments for muscular dystrophy, Alzheimer's, cancer, liver disease, congenital blindness and blood disorders like haemophilia and sickle cell disease. Other inherited diseases like Huntington's disease and cystic fibrosis are also being targeted. However, it is recognised that many of these diseases involve multiple genes, possibly hundreds if not thousands. As such, the development time in which treatments might be perfected may be much longer than any marketing hype might currently imply. However, by way of a caveat to this somewhat negative assessment might be parallel developments in AI and robotics that lead to exponential progress in all other fields of research.
However, should technology ever reach this level of genetic manipulation, it is possibly naïve to assume that it will not pursue other forms of more fundamental enhancements to the human genome, e.g. intelligence. In a recent study of over 78,000 people, 52 genes were identified and thought to be significantly associated with intelligence, although there are potentially many more thousands of genes that contribute to a multitude of different cognitive abilities. While the nature versus nurture debate can cloud the discussion of the correlation factors that quantify cognitive abilities within genetics, we might again consider an initial computer analogy with respect to the division of hardware and software. Within the general and limited scope of this analogy, we might assume that it may be possible to load the latest software onto old hardware but then quickly realise that the old hardware lacks the processing power, both in terms of processing speed and memory, to support all the functionality of the new software. In this context, if we assume that the human brain may be analogous to hardware, i.e. it is the physical platform on which all cognitive processes operate, we might gain some insight regarding the correlation weighting between the genetic nature versus the educational nurture of intelligence.
Note: The Wilson Effect suggests that environmental factors can dominate the measure of IQ in early years, when genetic factors may only have a 20% influence, but grows during adolescence such that genetic effects may come to account for 80% of an IQ score in adulthood. As such, this suggests a correlation weighting biased toward the underlying genetic nature of intelligence in adulthood. However, even if we were to assume a 50-50 split between nature and nurture, selecting for genes known to enhance the general idea of intelligence could lead to significant improvements in IQ scores in adulthood.
While recognising that this is still speculation, not a proven future reality, it still appears to be a reasonable assumption that research will continue in the direction of genetic enhancements, irrespective of the wider public debate on ethical issues. The rationale for this assumption is based on economic and political considerations in a competitive world, where all sides assume the other to be secretly pursuing an advantage. Of course, over time, such developments would still presumably filter into certain sections of society, which may then contribute to the social stratification previously suggested, which would undoubtedly be compounded by other developments.