Nature versus Nurture Debate

As a basic introduction of the ‘nature versus nurture’ debate, the issue of evolution is often polarised in terms of two factors, i.e. internal genetics versus external environment. While we might accept that this debate can applied to other biological lifeforms on planet Earth, the main focus of the debate is invariably orientated towards human life, as depicted right, without really giving too much thought about the direction this debate might go in the future. However, we will first attempt to extend this introduction by making some basic distinction between ‘nature’ and ‘nurture’, where the former is essentially biological in scope and subject to genetic adaptation, while the latter might be linked to any form of environmental effect. Generally, we might accept that nature and nurture can operate on very different timescales, which then leads to an initial question of interest.

Will the future be determined by nature or nurture?

In order to even start addressing the question above, we possibly need to be a little more specific about the scope of nature and nurture plus clarify the underlying assumption that humanity will play a key role in determining this future. In this context, it might be highlighted that the opening page of website-4 suggested that past evolutionary processes have presented humanity with an opportunity to define the purpose, and future, of its own existence. However, it also suggested that this opportunity may never be realized by many, possibly for no fault of their own, due to the makeup of their DNA. This statement is based on the assumption that life is subject to a unique blueprint, encoded into DNA, which determines the scope of both the physiology and psychology of all species on planet Earth, including humanity. The empirical evidence in support of the role of DNA has previously been outlined in the Biological Model discussion, such that this detail will not be repeated. However, while there is empirical evidence that the evolution of any species has been based on mechanisms outlined in the ‘Inheritance Model’ discussion, it is also highlighted that the Genetic Model of inheritance is also subject to random mutations plus many additional mechanisms, such as ‘genetic recombination’ and ‘genetic dominance’, which lead to changes in the genotype and phenotype of a species.

Note: At this point, it might be highlighted that the central premise of Darwinian natural selection is that all life has adapted to environmental change, which it is assumed takes place over many generations. However, today, it is recognised that environmental change in the form of social developments may take place within a single generation.

In addition, a developing 'Epigenetic Model’ suggests that phenotype changes may take place via a mechanism that does not involve direct alteration to the overall DNA sequence. Within this model, genes can be switched on or off as a result of environmental factors, possibly internal and external, such that it might blur the previous distinction between ‘nature’ and ‘nurture’. Of course, if humanity continues to develop the ability to change both the nature of its genetic blueprint and its external environment, then the question about nature and nurture may not be the central issue of concern as both will increasingly become man-made.

But do the various assumptions about man-made evolution need to be challenged?

While humanity might rightly assume itself to be the pinnacle of intelligent sentient life on planet Earth, this does not necessarily guarantee that man-made evolution will be a success. For even a brief review of human history might suggest that a multitude of other factors will play a role in future developments – see Brave New Worlds for further details. Therefore, we might still need to consider the idea of the ‘human condition’ being the result of both nature and nurture - see The Elephant in the Room for a possible wider perspective.

Note: The ‘human condition’ is undoubtedly a multitude of complex factors built into our DNA and then compounded by ever-changing developments in our surrounding environment, i.e. modern society. However, we might possibly attempt to characterise the net effect of all these factors in just four words: “Not in my backyard”. While grossly simplistic, we might recognise that people have a tendency to only agree to change as long as it does not adversely affect them.

Let us continue by initially assuming that genetic evolution provides the explanation of the spread of physical and mental abilities of ‘homo sapiens’ in the world today, which possibly dates back some 250,000 years. Of course, we might also recognise that the human condition has been affected by nurture factors, which might initially be introduced in terms of Maslow’s Hierarchy of Needs, although this hierarchy needs further consideration in terms of the growing complexity of modern society. Within this evolutionary timeline, Darwin’s theory of natural selection was forwarded long before the development of present-day genetics, although it was generally accepted as a potential mechanism by which characteristic traits of a species might be passed on to subsequent generations. In this historic context, the term ‘natural selection’ might be seen in contrast to some form of ‘artificial selection’, which for the purposes of this discussion will be described as ‘man-made’. However, it has to be recognised that this very brief and overly simplistic summary of the evolution of ‘homo sapiens’, undoubtedly omits many important facts, such as the apparent 10% reduction of the human brain over the last 20,000 years.

Note: There is still much controversy about the cause and effects of the apparent reduction in brain size. One idea simply relates brain size to body mass, another forwards the idea of diet as a key factor. However, there is also the possibility that the larger brain size of earlier hominids was a reflection of the broader range of survival skills initially needed in prehistory long before Maslow’s needs could be adequately provided by extended social groups. Given this controversy, it might be premature to equate brain size with the general concept of IQ.

Despite highlighting a note of caution in the last sentence above, we might still consider the potential interaction between nature and nurture, especially over the last few hundred years, where humanity has become increasingly dependent on the protection offered by modern society. In this context, we might return to a quote by Darwin, even though it may now appear politically incorrect in today’s world, for it highlights a potential consequence of social evolution on human genetics.

“With savages, the weak in body or mind are soon eliminated and those that survive commonly exhibit a vigorous state of health. We civilized men, on the other hand, do our utmost to check the process of elimination; we build asylums for the imbecile, the maimed, and the sick; we institute poor-laws; and our medical men exert their utmost skill to save the life of every one to the last moment. Thus, the weak members of civilized societies propagate their kind. No one who has attended to the breeding of domestic animals will doubt that this must be highly injurious to the race of man.

As previously highlighted, the genetic nature of evolution was not understood by Darwin, when he published the 'Origin of Species by Means of Natural Selection ’ in 1859 or 'The Descent of Man’ in 1871. However, the results of selective breeding of domestic animals had been empirically understood for centuries, such that the quote cannot simply be ignored just because modern sensibilities do not like the inference. Therefore, the next question has to be considered.

Is humanity immune to selective breeding?

Note: First, by way of immediate clarification, this discussion is not a veiled disguise to introduce any ideas that might be associated with the dark side of eugenics, where selection is predicated on race or ethnicity. However, the question above has to be legitimate, if we accept the empirical results of selective breeding, whether by design or accident.

Having hopefully clarified the purpose of the discussion to follow, the focus will now return to some potential causes and effects associated with both genetic and social evolution. At this point, it will now be argued that humanity has operated outside the normal definition of natural selection for possibly tens of thousands of years and, as such, has submitted itself to a form of selective breeding that, in part, is alluded to in Darwin’s quote above. However, in opposition, there is a school of opinion that claims there has been no significant genetic change to the human genome in the last 50,000 years, such that the astounding development of successive human civilisations over the last 10,000 years must have been built on the same basic physical and mental abilities of our ancestors. If so, the perceived evolution of humanity throughout recorded history must be attributed to developments within the external environment, i.e. nurture not nature. Of course, today, there are many obvious racial and ethnic differences in physical appearance that would seem to contradict the certainty of this position. Although there is still considerable ambiguity surrounding the correlation of brain size to IQ. This latter issue may also be considered a taboo subject, for while people seem to accept the reality of a statistical distribution of physical abilities in sports by both race and ethnicity, there appears to be extreme reluctance to consider a similar statistical distribution when correlated to IQ.

Note: Charles Murray’s book entitled ‘The Bell Curve’ was published in 1994, although its findings and conclusions are still the subject of much controversy, possibly more political than scientific – see discussion ‘Social Background’ for more details. While this issue will not be revisited at this point, it will be stated for clarification that statistical distribution deals with the probability within a population as a whole and does not make any inference about any individual within this population.

Again, having taken a detour to hopefully provide some reassurance to those adherents of political correctness, we might return to the issue of human evolution up to the present-day. While somewhat speculative in scope, the following evolutionary changes are supported by varying degrees of empirical evidence. At the genetic level, these evolutionary changes include known physical and biological adaptations, e.g. skin colour, disease resistance and lactose intolerance, but also suggest personality and cognitive adaptations, although these are often more difficult to quantify. There also appears to have been a trend towards reduced physical strength and aggression in some populations, which while probably counter-productive to survival in hunter-gatherer groups proved to be less of an issue in earlier agricultural communities and possibly actively ‘nurtured’ in some modern societies. If we accept this type of general trend in physical attributes, it seems unreasonable to assume that the general notion of intelligence, especially as it pertains to abstract concepts such as mathematics, would not have been subject to some evolutionary change over the last 10,000 years. If so, we might speculate that evolutionary change, both physical and mental, have continued based on selective adaptations to changes in the external environment, i.e. increasingly sophisticated social groups. Of course, history tells us that the developments of ever more sophisticated civilisations was not uniform and varied enormously by geography.

Note: Today, the genome of various people around the world can be catalogued in terms of racial and ethnicity traits, which may then be traced as genetic markers linked to earlier human migrations into different regions and geographies. While this type of evidence is still subject to much research, it does not seem unreasonable to correlate the activation or suppression of certain genes to earlier migrations and cultural differences. Simply by way of an example, it is estimated that nearly 65% of the global population show symptoms of lactose intolerance, although this intolerance is subject to much geographic variants. Northern Europeans show less than 10% intolerance, while 95% of Asians and Africans exhibit this intolerance. Genetics has traced this mutation back 10,000 years to Northern Europe with the suggestion that the mutation was possibly linked to the domestication of dairy animals in Europe some 12,000 years ago. These earlier populations potentially relied on various dairy products as an essential source of food, such that the natural ability to tolerate lactose in infancy extended into adulthood. As the domestication of dairy animals did not occur until much later in Asia and Africa, the indigenous population in these regions did not develop the same degree of lactose tolerance.

While some of the ideas being presented are somewhat anecdotal, it does appear that the internal genetic nature of humanity has continually adapted in response to changes in the external environment over thousands of years. However, whether such adaptations can really explain the exponential increase in technological developments over just the last 200 years may appear questionable, such that other explanations may be necessary. One possible explanation for the increasing rate of development, which can be traced back to the earliest civilisations, is an ability to better share and distribute information that initially provided the foundation on which all human knowledge ‘evolved’. Ten thousand years ago, information sharing was initially restricted to the spoken word and therefore confined to very localised regions. However, the development of the written word was clearly a step change in this ability, although the means of distributing the information to a wider population was still limited. Again, we might recognise another step change in ability with the invention of the printing press, which not only allowed the information to be replicated in volume, but also distributed across a much wider geography. Today, we might easily see the extrapolation of these earlier developments into the information age, which is now supported by computer processing, global communication networks and a multitude of graphic and application interfaces.

But what of the future?

While any prediction about future developments has to be considered in terms of probability, not certainty, it might be accepted that an era of accelerating AI-Robotic Developments is no longer science fiction. If so, such development will impose a profound environment change on humanity, where many may not have time to adapt – see AI Perspective for more details.

 Note: Again, at this point, we might question whether the line between nature and nurture will become increasingly blurred as the scope of the environment, as defined by modernity, becomes dominated by accelerating technological change. While we started out with the assumption that natural selection might have been partially superseded by man-made selection, we might now have to consider whether the future might ultimately be determined by an entirely different form of selection.

To underlined the potential implication of the last sentence above, the image right is being used to highlight what many might see as a disturbing prospect of a purely technology-led evolution, should it come to challenge humanity’s dominant role in the future of life on planet Earth. However, before addressing this concern, the image right was originally used as part of an evolutionary model called Hybrid AI, where incremental developments take place over a timeline of some 200-300 years. This timeframe was based on what was felt to be a more practical assessment of the acceptance of technology developments, when considered within the wider scope of society as a whole, i.e. political, economic and social – see Catalysts of Change for more details. In addition, it was hoped that this timeframe might provide more time for certain sections within each future generation to adapt to the changes being suggested, although this might be more reflective of wishful thinking than any deep conviction.

Note: By way of another aspect of the how and why society changes - see discussion entitled ‘The Nature of Consensus’. This discussion suggests that accumulating change in society is not really planned, invariably has unintended consequences and is never decided by anything that truly represents a democratic majority.

In part, the general inference of these earlier discussions is that the Darwinian idea of ‘survival of the fittest’ does not simply disappear in some utopian future, if winners and losers remain a consequence of any process of change. In retrospect, we recognise the process of natural selection also created evolutionary winners and losers that applied to all lifeforms. However, probability suggests that a future, which remains subject to the human condition, will still continue to produce its own form of winners and losers brought about by technology developments of all kinds. Of course, probability also suggests that this on-going process of man-made evolution will undoubtedly trigger corresponding changes in the political, economic and social infrastructures that now underpin most modern societies.

But are there other possible implications associated with the image above?

As outlined in this discussion, the line between nature and nurture may become increasingly blurred, if the scope of man-made manipulation of the genetic code continues to develop. Of course, society might place restrictions on such developments, but probability suggests that this will only slow and not stop future developments in this field. Likewise, as outlined in the discussion ‘Technology Catalysts’, developments in genetics is but one of many potential technology developments that will undoubtedly change human society and possibly affect all species on planet Earth. However, the implication in the image possibly suggests something more profound than just the manipulation of the human genome, which has been previously discussed in terms of both ‘AI and Robotic Developments’. While the timeline of these developments might be debated, the general trend that many are predicting might be characterised in the diagram below.

Here we see the suggestion that complexity will increase exponentially, primarily driven by technology change, while human ability remains constrained by genetic evolution. If so, humanity may have little choice but to surrender control of many of its critical infrastructure to autonomous AI systems. Of course, should such developments continue, the combination of AI-Robotic Automation would have the potential to replace humans in many areas of employment and, in so doing, become an Economic Catalyst of change. So, while this is only a prediction, not certainty, it is difficult to see how the current trajectory of human society can avoid this future without some form of regression, the consequences of which would then threaten the lives of billions, who are almost totally dependent on the complexity of the modern world.

So, does humanity have a long-term future?

While this might appear to be an extremely depressing question to table towards the end of this discussion, it too has to be put into evolutionary context. Any review of the earlier evolution of life on planet Earth shows the transitory nature of all species when subject to environmental change to which they cannot adapt. While humanity might assume itself to be an exception, which is questionable, it is not necessarily without some foundation, if characterised in the form of a more specific question.

Will humanity exist in ten, hundred, thousand or even a million years?

There are two aspects of this question that need to be considered, first, the length of time involved and, second, what do we infer by the word ‘humanity’. Clearly, as the timeframe extends ever further into the future, our ability to foresee all possible change, both genetic and environmental, possibly reduces ever closer to zero. However, it is in the nature and nurture of the human condition to consider the issue of change as a somewhat academic issue, provided it does not affect us personally, which we might initially perceive in terms of our own life time and then extend to that of our grandchildren, if already born. While each generation possibly has its own perception of humanity, both in terms of its genetic nature and nurturing environment, it is clear that this perception not only changes with time, but also in the details of its reality. In this context, we each come to some understanding of our own humanity, which is a subjective product of ‘time and place’ into which we are born. However, what this discussion has attempted to highlight is that natural and man-made selection have come to operate on very different timescales and that humanity, whether by design or accident, appears to be destined to initially follow a path of man-made evolution, which will continue to create both winners and losers. Of course, in the longer term there is the suggestion that even man-made evolution might be superseded, but this is possibly the subject of another essay.