Tuesday, 15 December 2015

Why is group selection necessary? To solve the fundamental problem of life, which is error catastrophe/ mutational meltdown

The situation where group selection is a necessary explanation, is in order to solve the primary problem of life - which is the sustaining of life in the face of the tendency to mutational meltdown (which is the biological special case of the general phenomenon of error catastrophe).

The main problem of life is not in the initial arising of replicating entities - but in their remaining alive across generations given the intrinsic tendency of informational errors to occur and to accumulate - leading to extinction.



The problem of error in information can be diminished by better quality replication, and by repair of errors - but to do this requires relatively complex adaptations, and these must arise in a context where errors are accumulating all around.

It seems that the simplest and most reliable - and indeed, ultimately always necessary - mechanism for controlling informational errors is selection. In other words, there must be reproductive suppression (preferably elimination) of those entities which have accumulated significant informational errors - these errors must be eliminated from reproductive lineages before the information becomes so corrupted that extinction occurs.

This is the basic role of group selection. All living things need to develop networks of inter-individual communications; that is the individual entities must become a complex system. Complex systems are - by their nature - able to act to maintain and continue themselves; and the first and necessary self-perpetuation of the system is to suppress individuals with corrupt information.

In biological terms, individual entities gain deleterious mutations; and the first job in sustaining life is to eliminate individuals with deleterious mutations. This is most straightforwardly done by suppression of reproduction of mutationally damaged individuals (up to and including killing them).

This is a classic, indeed archetypal, situation of group selection. The reproductive interests of the group (that is the lineage) must prevail over the individuals - the group benefit is imposed upon the individuals - and this happens because the group has itself become an entity (i.e. the group has become a complex system) due to its relatively dense network of inter-individual communications.

So, the necessary step in the evolution of any potentially multi-generational form of life is that group selection must apply.

Absent group selection, and life will be snuffed-out by mutation accumulation and mutational meltdown almost as soon as it has arisen.

Hence, group selection is absolutely necessary to life.

Group selection does not require competition between groups

An important consequence of reconceptualising group selection in terms of complex systems theory is that group selection no longer requires competition between groups.

this was a serious constraint on old concepts of group selection, because it was a stringent criterion for groups to replicate, over multiple generations, the kind of competition which is so often seen between individuals - with additional problems of group cohesion, and the need for the spread of adaptive mutations (beneficial for inter-group competition) within a group.

Instead, group selection is assumed to occur whenever there is a sufficiently dense network of communication and interaction between individuals sustained across a sufficient number of generations (how many generations are required for group selection to have a significant effect depends on the density, hence selective strength, of the system of communications) - remembering that 'the system' is abstract and consists of communications, and the system is not the physical individuals.

(The physical individuals are termed 'communication units' and are strictly regarded as outside of the abstract system - not a part of the system - but their function is instead to generate and receive the communications.)

So group selection can occur even when there is only one group.

Group selection should therefore be conceptualised as something that happens individually, to each group - rather than as a consequence of competition (or any other form of interaction) between groups.

The divergence between group characteristics is a consequence of the different selection pressure operating on each group - as a consequence of each group having a different system of dense inter-communications.


Monday, 14 December 2015

Reconceptualizing group selection in terms of complex systems theory

Group selection can roughly be defined as a form of natural selection by which the fitness (probable reproductive success) of the group is maintained or enhanced, even at the cost of reduced fitness of individuals in that group.

It is generally considered, within current or recent evolutionary biology, that group selection is an error, a misunderstanding, the explanation or last-resort or so rare in nature as to be insignificant.

By contrast, I regard group selection as necessary for any other kind of selection - in other words, without group selection there can be no build-up of complex adaptations: group selection is necessary in order to maintain complex entities - indeed group selection is necessary to the sustainability of life itself.

So, group selection - far from being insignificant or a last resort, is ubiquitous, found everywhere.

However, in arguing this I am engaging in a re-conceptualization of group selection - in particular I am using definitions derived from a particular theory of complex systems: that associated with Niklaus Luhmann.

[See Appendix and associated references in:


In considering group selection it is worth having a definition of what constitutes a group of the type capable of acting as a selection pressure on the individuals composing the group; since the minimal requirement of group selection is the presence of a suitable group that is stable (in those key respects which enforce selection) over a sufficient number of generations.

(Most of the ways of conceptualizing groups selection are, I believe inadequate)

This question can be reduced to the definition of a biological entity.

A biological entity is a (relatively) concentrated and sustained network of communications and interactions. Thus a single cell, a multicellular organism, an organ (such as the heart, or a gland) within a multicellular organism, and the social group in social organisms may all be considered to be entities.

For example, in social animals (including humans) that which makes them social animals can be defined as a sufficient density of particular types of communications and interactions between individuals - sustained across sufficient numbers of generations - such that this acts upon the individuals to shape behaviour by mechanisms that are transmissible between generations (for example, by inducing genetic, or some types of epigenetic, change of individuals).

In other words, the group itself displays a system-autonomy from the individuals which compose the group - therefore the group itself is a selection pressure on the individual animals within the group.

What is meant by autonomy? That the group entity operates to sustain and expand and/or reproduce itself - this being a defining property of all complex systems.

If an emergent complex system (occurring by chance) were to lack the ability to sustain and reproduce itself, it will soon simply cease to be - and would not be observable (or only momentarily so).

This is because a system is defined in contrast to its environment, and the basic property of a system is to separate itself from the environment in a context where chance/ entropic change will tend to assimilate the system into the environment (e.g. this happens after death).

Therefore any complex system which is sustained, must have the ability to sustain itself - to re-make and re-produce itself in the context of its environment - and for social groups individual organisms are a part of its environment. Therefore, social groups are buffered against the individuals which constitute it - but this is not a paradox, because what makes the social group definable as a complex system is the interaction of inter-individual communications, therefore not the actual physical individual organisms.

This may clarify the current confusion about what is 'doing the selecting' versus what 'gets selected' - the so-called levels of selection problem (with levels such as genes, organisms or groups). Instead, of physical things, the problem is reconceptualized in terms of communications; instead of physical things, the problem is reconceptualised in terms of abstract systems; instead of hereditary information conceptualized in terms of physical things, the problem is reconceptualised in terms of systems having the intrinsic property of self-sustaining and reproduction.

Instead of looking at things such as gene frequencies in populations, the focus moves to things like the density, frequency and complexity of communications and interactions.

This, of course, represents a 'paradigm shift' in discussing selection in biology - and it is notoriously difficult to argue in favour of a paradigm shift - especially when the current paradigm is yielding security, status and funding.

Nonetheless, if the new complex-systems paradigm can be grasped, I think its explanatory superiority - especially in terms of clarity, and in terms of explaining some of the key problems of biology such as 1. the origins of biological life and 2. the major transitions in evolution (e.g. evolution of the cell, the eukaryotic cell, multicellular organisms, sexual reproduction, social organisms) is very clear.


What makes a human group capable of group selection - including the role of agriculture in the evolution of geniuses

Group selection can roughly be defined as a form of natural selection by which the fitness (probable reproductive success) of the group is maintained or enhanced, even at the cost of reduced fitness of individuals in that group.

In considering group selection it is worth having a definition of what constitutes a group of the type capable of acting as a selection pressure on the individuals composing the group; since the minimal requirement of group selection is the presence of a suitable group that is stable (in those key respects which enforce selection) over a sufficient number of generations.

(Most of the ways of conceptualizing groups selection are, I believe inadequate)

This question can be reduced to the definition of a biological entity.

A biological entity is a (relatively) concentrated and sustained network of communications and interactions. Thus a single cell, a multicellular organism, an organ (such as the heart, or a gland) within a multicellular organism, and the social group in social organisms may all be considered to be entities.

For example, in social animals (including humans) that which makes them social animals can be defined as a sufficient density of particular types of communications and interactions between individuals - sustained across sufficient numbers of generations - such that this acts upon the individuals to shape behaviour by mechanisms that are transmissible between generations (for example, by inducing genetic, or some types of epigenetic, change of individuals).

In other words, the group itself displays a system-autonomy from the individuals which compose the group - therefore the group itself is a selection pressure on the individual animals within the group.

What is meant by autonomy? That the group entity operates to sustain and expand and/or reproduce itself - this being a defining property of all complex systems.

If an emergent complex system (occurring by chance) were to lack the ability to sustain and reproduce itself, it will soon simply cease to be - and would not be observable (or only momentarily so).

This is because a system is defined in contrast to its environment, and the basic property of a system is to separate itself from the environment in a context where chance/ entropic change will tend to assimilate the system into the environment (e.g. this happens after death).

Therefore any complex system which is sustained, must have the ability to sustain itself - to re-make and re-produce itself in the context of its environment - and for social groups individual organisms are a part of its environment. Therefore, social groups are buffered against the individuals which constitute it - but this is not a paradox, because what makes the social group definable as a complex system is the interaction of inter-individual communications, therefore not the actual physical individual organisms.

So, when we consider group selection of humans, we should be looking at the frequency and complexity of communications between individuals. from this perspective, I think we can see that the emergence of complex agriculture will have had the effect of increasing the density of inter-individual communications by expanding both the size of the social group and also the necessity for planning, specialization and coordination of agricultural (and also industrial) economic activities - with the extra communications necessary to enable this.

What about the industrial revolution? From a communications perspective, the key factor about the industrial revolution is expansion of the population, and a much more extensive but less concentrated network of communications. I would conjecture that the switch from face-to-face to written (and later digital) interpersonal communications was associated with a great reduction in the complexity of communications.

Direct, face to face communication is informationally far richer, far denser, than the abbreviated, abstract, precise but simplified communications of electronic media (or than the preceding bureaucratic communications such as 'memos' and the 'minutes' of meeting). So, it is likely that industrialization is associated with a reduction in the complexity of group-level entities, and a reduction in the strength of group selection - and therefore with the re-emergence of individual level selection.

Hence, modernity is characterized by increased atomism of individuals, increased individual versus individual competition; and a loss of the strength of 'communities'. This will lead onto changes among individual humans, to make them more individual and less adapted to group cooperation.

In conclusion, it is reasonable to assume that in human history, group selection was strengthened by at least some forms of agriculture; and that individual humans in complex agricultural societies are more strongly group selected than the individual humans in 'simple' hunter-gatherer societies (i.e. 'simple' hunter gatherers are those without either food storage or complex technologies).

In terms of genius, which Dutton and I argue (in our forthcoming book The Genius Famine) to be a group selected phenomenon (with the genius serving a specialized function to benefit the reproductive success of the group), this fits with the historical evidence that some types of complex agricultural society seem to provide the optimal selective environment for producing the highest density of geniuses - since these are probably the most group selected of societies.

Monday, 7 December 2015

Where to look for group selection (globalization reduces the strength of human group selection)

The 'standard' attitude to group selection in mainstream evolutionary biology is that it is an explanation of last resort - which should only be invoked when the possibilities of organism-level selection (by 'selfish gene' mechanisms) have been exhausted.

But from a complex systems theory perspective group selection should be investigated, as the first line of enquiry, whenever certain conditions prevail - as follows:

A complex system can be identified when there is a concentrated and lasting network of communication-interaction between entities - when we find such a situation in biology (or elsewhere), then we may assume that we have an entity which may be selected. 

For example, such dense communication-interactions may be identified within a single cell, between the cells of a multi-cellular organism, or between the organisms in social organisms.

Therefore each relatively discrete human group (of whatever size) - where there is a much greater density of communications within that human groupings than exists between such human groupings - is a situation where group selection would be expected.

Group selection was therefore usual through much of human history when there were groups that had little or no communication-interaction between them (for example, when geographically separated, or separated by any other 'barrier').

But the strength of group selection is reduced by any significant increase of communication-interaction between groups.

Therefore (all else being equal) 'globalization' is expected to reduce the strength of group selection for whatever groups are included; since globalization refers to a significant increase in the communication-interaction between groups.

The modern 'globalized' world is therefore a world in which levels of local and national group selection has been weakened; and the most modern parts of the world are those in which group selection has most been weakened for longest.

In such a situation, it can be assumed that individual level selection will have been weakening group selected traits for several generations - with the effect of diminishing the instinctual basis of social cohesion. 

In summary; group selection is not so much a consequence of competition between groups, as it is an intrinsic aspect of dense communication-interactions within groups in a situation with little communication-interaction between groups.

Reference - see Appendix of: http://www.hedweb.com/bgcharlton/modernization-imperative.html

Monday, 30 November 2015

Religion as the proximate method of Group Selection in humans - implications of its removal

It seems reasonable to regard religion as the proximate method of group selection in humans - in other words, when humans groups compete and evolve group adaptations, these are instantiated by means of religions. Individual humans have adapted to live in a context of religion; and when religion is absent, human behaviour becomes maladaptive - because human instincts are 'designed' to function in a religious environment.

It has long been a consensus among (secular) social theorists that the main (secular) function of religion is social cohesion - that is, religion can enable larger and more complex forms of social functioning; including the stimulation and enforcement of motivation, altruism, long-termism.

Since all humans - until recently in The West - have evolved in the context of religion; therefore religion must, over multiple generations, have had gene-selective consequences that shaped individual instincts and behaviours.

Group selection entails that group behaviour be referenced to something outside the group. This is what groups cohere-around, organize around, cooperate to promote. Throughout history this 'something' has been religion - variously the spirits, the gods, or One God.

Since this has apparently been the case throughout all known history and stretching back into pre-history, individual humans have evolved to be coordinated by religion: religion is a built-in, innate expectation for each individual human; and if religion is absent, then individual behaviour lacks a necessary adaptive context.

Having been under group selection for so long, where each individual functioned as a 'component' part of a religious society; then individual level instincts will relatively have atrophied. So, remove the religion from an individual human being, and the behavioural rules and patterns lack context, and are maladaptive.

Individual humans absent religion are un-equipped to pursue their own reproductive success.

Religion is therefore the medium for, and regulation of, altruism - which is the propensity of individuals to sacrifice their own short-term comfort and pleasure, health, survival, and ultimately their reproductive success, to that of the group.

In sum: Humans just are adapted to serve the group via religious structures which reference individual behaviour to some-thing outside the group.

Clearly, 'the group' in group selection will be bounded - and cannot be scaled up or down, made larger or smaller, indefinitely; since there must be mechanisms for rewarding group-helpful, and suppressing group-harmful, behaviours - and such mechanisms (like status or material rewards, shaming or physically-coercive sanctions) differ between religions, and these do not scale indefinitely in either direction.

Group selection is strong: it must be stronger, in significant respects, than individual selection: group selection must be strong enough to overcome individual preferences.

This means that group selection operates to affect the nature and strength of individual preferences - individual preferences have until recently always operates in the context of religiously-mediated group imperatives; because, over many generations, selection will (overall) tend-to mould individual preferences significantly to serve the needs of the group.

While group selection has been significant on all humans everywhere and at all times; European populations (also probably East Asian populations, perhaps to an even greater extent?) have been strongly group selected for large-scale cohesion over many dozens of generations; so that the effects of group selection are more significant in those of European descent than in most other populations.

This implies that the selection effects of religion on individual behaviour has been more significant in those of European descent than in most other populations. 

European populations had Christianity as the proximate mechanism of group selection for hundreds of years; shaping the instinctual basis of the individuals. And Christianity must have been an extremely powerful mechanism of group selection, because it enabled what are, by world historical standards, very large cooperating groups persisting over multiple generations.

(By contrast, simple animistic religions are able to enforce cooperation of some scores of people; more complex totemistic religions can enable the cohesion of thousands; and the complex and literate Temple religion of Ancient Egypt enabled some millions of people to cohere for three thousand years! Christianity seems to have been similarly powerful to the ancient Egyptian religion, sustaining complex cooperation among millions of people.)

It may therefore be assumed that the people of Western nations inhabited by those of European descent evolved to become extremely dependent on Christianity in order to be adaptive.

These same people, with the same instincts that operated within a strongly Christian context for so many generations, now find themselves in a society from which Christianity has been (all but) deleted.

Individual behaviours now have a very different environment in which to operation - indeed, the environment is in multiple respects and increasingly anti-Christian. Little wonder that grossly maladaptive behaviour is currently rife - indeed mainstream.  

Sans religion, Western populations lack the instinctual basis for individual level survival and reproduction, since these instincts long since atrophied - and atrophied to a more extreme degree than in most populations.

Now basic instincts such as reproduction, group survival, defence, long-termism for group goals, self-sacrifice for the group are defective or absent. The interaction between individual instincts and the non-religious environment is producing multiple, population-lethal pathologies. Voluntary subfertility is nearly universal; native population-replacement is advocated and celebrated; maladaptive forms of sexuality are common and actively-promoted; self-mutilation is escalating, normal and admired; the clamour for on-demand, comfortable, 'assisted' suicide grows greater with each year...

Living without religion, but with a genetic makeup that had evolved to assume religion, to expect religion, and to live-within religion; the instinctual basis of Europeans, including their powers of evaluation and judgement, are revealed as both ineffective and inappropriate.

Of course, under current conditions and continuing present trends; eventually and after many generations individual level selection may lead to the evolution of new effective and appropriate instincts that aimed-at individual survival and reproduction - then, presumably, large scale societies would break down into much smaller competing units, since such individuals would have evolved to be resistant to the social cohesion mechanism of religion.

Alternatively, the adaptiveness of European populations may be strengthened by the restoration of Christianity.

The 'scientific method' of genius - Attention, Intuition, Imagination

THE big problem in the philosophy of science is: Where do valid hypotheses come from?

The problem is that the 'search space' for valid hypotheses is vast, and nearly all possible hypotheses are wrong.

So how do creative scientists discover true hypotheses - that is, hypotheses that are basically valid explanations, suitable for research and development by standard methods?

Another problem is that most of what gets called science is not primarily creative, but uses already-made/ discovered hypotheses to extrapolate and interpolate (fill the gaps between) their assumptions, by deploying fairly standard methods of 'trial and error' in the domain of 'research and development'.

In other words, creative science corresponds closely with what Thomas Kuhn termed 'revolutionary' science (although the creative and paradigm-changing 'revolution' is mostly at a much smaller and more specialized scale than the example Kuhn used); while non-creative science corresponds to what Kuhn termed 'normal' science.

In practice, I think creative science uses something like the following 'method':

1. Focus
2. Effort
3. Honesty

Focus: The scientists focuses on some problem or topic - this is in one sense chosen by the scientist; but in another sense the problem chooses the scientist: he is firstly gripped by a problem and secondly consents to work on it and thirdly he is able to do this.

Effort: The scientist then puts in a sustained and considerable effort directed at the problem. This requires motivation, since it is seldom that external influences will be pushing him to pick this specific problem, and to keep working on it in the face of distraction and discouragements.

Honesty: The scientist must be honest - he must want to know the truth, must behave truthfully, and must communicate his findings and beliefs truthfully. Creative science is difficult and rarely accomplished, and unless the individual is honest he will find it much quicker and easier to fake a discovery (more or less) than actually to make one; easier to hype or otherwise distort a discovery rather than to communicate it as clearly as possible.
     Also, an attitude of honesty is necessary in order that the phenomenon comes more clearly into view; to clear-away the clouds and distortions that obscure it. The ability to know is typically prevented by wishful thinking and other types of preconception - unless there is a honest desire to know the truth, then the truth will not be known.

Given the above general set-up - which as-it-were places the scientist into a position from which creative science can be done - what then is the micro-method of the creative scientist?

1. Attention
2. Intuition
3. Imagination

What happens with creative science is that the scientists is paging attention, is absorbed-by the phenomenon; then looking within himself (intuition) he apprehends the reality of the situation by his imagination.

In effect, the 'answer' appears in the scientists imagination - or, to put it more exactly, the answer is communicated to the scientist's imagination by non-perceptual means.

Negatively expressed, creative understanding does not come via the senses (vision, hearing, touch, taste, smell); it does not come via the perceptions; it does not come from memory.

How then does the answer arrive in the imagination? I imagine it as a process akin to sympathy or empathy - in which an understanding of the phenomenon induces the same phenomenon in the imagination (or rather some kind of 'model of the phenomenon).

This entails either that the scientist has some sort of built-in prior understanding which is elicited by the process of contemplating the phenomenon (rather as Plato said that 'learning' was actually a matter of making explicit what was already known) - or else that the understanding is communicated-to the imagination from some external source (which would correspond to 'inspiration').

So, the primary source of creative understanding is located in the imagination of the scientist, and by this account it is valid - the understanding is valid, albeit neither complete nor undistorted due to the constraint of any phenomenon being more complex than the finite representation of it in the imagination).

But so far, the understanding is 'subjective' in the sense of being private, inside the mind of the scientist - the scientist must then communicate this understanding into the public domain via language - and in doing this there will inevitably be selection, distortion and also the possibility of misunderstanding from those trying to understand the phenomenon from its public description.

That is about as far as I can go in describing what happens - and it leaves open (or, at least, open to dispute) some fundamental aspects of the problem - such as where the imaginative understanding comes from and what makes it valid.

It creates the apparent paradox, that real, creative science comes from outside science - but this is surely true, in the sense that this is also found in other creative realms such as literature, music and art.

I think it would be found that the above psychological description fits the actuality of valid discovery - when such things are known. In my own experience I have found that my successes at valid creative breakthroughs - such as 'the malaise theory of depression' came after a sustained period of focused attention and contemplation of a phenomenon to which I was spontaneously drawn.

And when I failed to make a breakthrough in understanding (for example, I have not been able t understand Anorexia Nervosa) this was because I was not spontaneously interested and had failed to regard the matter with sustained attention.

Plus, of course, there is no guarantee of my reaching an imaginative understanding of any given topic - since I may have may have been insufficient attention so far (and the breakthrough still lies in the future), or I may personally be incapable of understanding for numerous reasons - or the phenomenon may be too difficult for anyone to understand, or I may have failed to be sufficiently honest and devoted in the nature of my contemplation.

But my point here is that the true 'scientific method' for creative discovery is not an algorithm or protocol - following which will yield breakthroughs; but rather a psychological, and indeed somewhat mystical, thing.

And that it involves a match-up between the scientist and the phenomenon which could be termed 'destiny' - a scientist may have a destiny to solve a particular problem, or a limited set of problems - but others will not be possible for him, since he lacks not just competence, but the necessary deep-motivation absolutely required in order to embark on focused, effortful, sustained contemplation of a particular phenomenon - a thing that may be discovered, but cannot be manufactured or imposed.

Friday, 20 November 2015

Negative emotionality, hyper-emotionality and hypo-emotionality as potenital causes of depression

Bruce G Charlton and Joseph Shaw

The broad diagnostic category of DSM Major Depressive Disorder (MDD) was established in 1980 – in practice it seems that MDD can be interpreted as inclusive of patients with a wide range of dysphoric feelings including depression, anxiety, mood swings and emotional blunting/ unemotionality [Watson 1988a, Nutt 2007]. In other words, depressive symptoms may be regarded as a consequence of more than one emotional state; rather as pain may be a consequence of many causes [Charlton 2009].

It has been argued that Major Depressive Disorder is therefore heterogeneous, and can be subdivided into at least three groups, each characterised by a distinctive emotional state.

Negative-emotionality (Negative-E) describes the most obviously depressive group, who mainly experience strong negative emotionality such as misery, anxiety, guilt, fatigue etc.

A second group would be Hyper-emotional (Hyper-E) who experience strong emotions in both negative and positive directions (e.g. they are emotionally unstable, hyper-responsive, subject to mood swings).

A third group would be Hypo-emotional (Hypo-E), with weak or blunted emotions in both negative and positive directions (e.g. they are ‘flat’, demotivated, unresponsive) [REF 1 Charlton].

These states may be characterized by each having a different pattern of
1. emotional strength and 2. Emotional direction (i.e. positive/ negative, both or neither).

As a first test of this hypothesis we conducted an internet survey on 251 subjects recruited through advertisements posted on several depression-related online communities (www.reddit.com/r/depression; www.nomorepanic.co.uk; www.depressionforums.org; http://talk-depression.org). Strength of depressive symptoms was measured using the Beck Depression Inventory [Beck et al 1961], while the strength and directionality of emotions was measured the PANAS (Positive and Negative Affect Scale) [Watson 1988b].

217 subjects were classified into groups of Controls, Negative-, Hyper- and Hypo-Emotionality by using the Positive-Affect (PA) and Negative-Affect NA) sub-divisions of PANAS:

Controls n=27, Lowest 25% NA, Highest 25% PA
Negative-E n=50, Highest 50% NA, Lowest 50% PA
Hyper-E n=76, Highest 50% NA, Highest 50% PA
Hypo-E n=64, Lowest 50%NA, Lowest 50% PA

Severity of depressive symptoms are shown in Table 1:

BDI Mean
BDI       SD
Positive-E Control

The results show that despite the ‘control group’ being in the Mild range for depressive symptoms on the BDI; all three of the hypothesized emotionality groups scored were significantly more severe in depressive symptoms than Controls; indeed within the ‘Severe’ depressive symptoms range for BDI scores.

These preliminary results seem clear and consistent with the hypothesis that depressive symptoms may be a consequence of at least three different emotional patterns – Negative-E, Hyper-E and Hypo-E. This conclusion, of course, requires replication in a clinical subject sample evaluated by face-to-face diagnostic interviewing. If correct, one potential implication may be that different emotionality sub-types could benefit from a different therapeutic approach; for example Hyper-E from a trial of serotoninergic agents, and Hypo-E from noradrenaline/ dopaminergic agents [Nutt et al 2007; Charlton 2009]. 


Watson, D., Clark, L. A., & Carey, G. (1988a). Positive and negative affectivity and their relation to anxiety and depressive disorders. Journal of Abnormal Psychology97, 346.

Nutt, D., Demyttenaere, K., Janka, Z., Aarre, T., Bourin, M., Canonico, P. L., … & Stahl, S. (2007). The other face of depression, reduced positive affect: the role of catecholamines in causation and cure. Journal of Psychopharmacology, 21, 461-471.

Charlton, B. G. (2009). A model for self-treatment of four sub-types of symptomatic ‘depression’ using non-prescription agents: neuroticism (anxiety and emotional instability); malaise (fatigue and painful symptoms); demotivation (anhedonia) and seasonal affective disorder ‘SAD’. Medical Hypotheses72, 1-7.

Beck, A. T., Ward, C., & Mendelson, M.  (1961). Beck depression inventory (BDI). Archives of General Psychiatry4, 561-571.

Watson, D., Clark, L. A., & Tellegen, A. (1988b). Development and validation of brief measures of positive and negative affect: the PANAS scales. Journal of Personality and Social Psychology54, 1063.

Tuesday, 10 November 2015

Genius as the ultimate altruist

Genius emerges from individualism - the genius just is an individual who is significantly and personally responsible for some major human accomplishment.

So the seedbed of genius is a society, or a kind of person, who is individualistic - and such societies and persons have been absent for much of human history. When the individual feels himself to be immersed in the group - genius is not possible; only when persons are self-aware, at least somewhat differentiated from their social group is genius possible.

This is presumably partly a matter of genetic change - but it is surely a matter of historical and cultural change: to all appearance, there has been evolution (in the sense of change) of consciousness. Socrates would not have been possible in most of the human world up to that time - perhaps in no other part of the human world until some parts of Ancient Greece?

But the genius is Altruistic as well as individualistic - and I mean, here, altruistic in terms of differential reproductive success (or 'fitness'). The average genius seems, as a matter of measurement, to have lower than average reproductive success - especially when we consider that throughout most of human history it was necessary to produce more than four children for the minimum replacement number of two of them to survive to adulthood in a sufficiently healthy state to reproduce. Not many geniuses had five children; many had none.

And aside from the estimated numbers; it is clear that the genius has less than usual interest in social and sexual success - and that this is intrinsic to genius, since the genius must have (at least during the years of his greatest accomplishment) a focus on his work that is intense and often obsessive - and such an investment of time, energy and resources entails a major shift in priorities away from those of normal (non genius) people.

Consider the sheer impact of a genius - of that one single person. The impact of a genius on the reproductive success of his group may orders of magnitude faster and greater than that of any possible person operating via natural selection. Some high status men may have had hundreds of children; but some geniuses have affected the survival and reproduction of millions of people.

As a recent example, Alan Turing (presumably) had no children and made zero genetic impact on the species; but without him the German Enigma code would not have been solved and the 1939-45 World war would have lasted longer and the casualties on the Allied side would have been significantly greater - without Turing the development of the computer would also have been delayed or impaired, with large and widespread effects.

My point is that (when his work is beneficial) a genius has an effect on a broad population of genetically unrelated and mostly unknown people which far outstrips the genetic level of impact. So the genius is both an individual yet, in effect, he is 'working for' other people (in the sense that any personal gains he may make from his work are likewise utterly dwarfed by his contributions to the larger group).

The situation therefore seems to be that when there occurs an increase in the incidence of genius, this arises from a human population in which individualism has been intensified; but that the genius does not pursue individualistic goals for individual benefit - it is as if the genius had been called-forth or created by the group in order to serve the group (not just his kin, not just those in the group who have a relationship - but a much wider group).

It is as if the genius is set up so that as an individualistic-individual, he willingly and by choice and effort, sacrifices his own (relatively modest) chance of genetic success in altruistically attempting to generate a much greater success in terms of survival and reproduction of his group.

Since altruism in biology is defined as acting to increase the reproductive success of other at cost to oneself, this makes the genius the ultimate altruist.

Monday, 9 November 2015

General properties of Group Selection and the 'group mind' (in relation to the adaptive production of geniuses)

The major function of group selection is presumably directly to promote the sustained reproductive success (lineal survival) of the group, in face of the spontaneous tendency for random change to promote the individual (and other lower level, below group) levels of selection.

For example, group selection would be of value in sustaining the cell in face of the tendency of cell components (for example the nucleus, or of evolvable organelles such as the mitochondria, chloroplast or centriole) to become 'free-riders' or parasites (taking net reproductive benefits from the cell, while contributing less than this to the cell, or nothing, or actively-harming the probability of the survival and ultimately reproduction of the cell).

A more clear cut example is the individual specialized cell in the context of a multicellular organism; there is a tendency for individual cells to evolve towards 'opting out' of the coordinated cooperation of the whole organism  - and taking more than they give. This is termed neoplastic change, and the tendency is what leads to cancers - cancers constitute an internally-generated cellular parasite.

But the main posited role for group selection has been in the context of animal society - especially in social animals (social insects such as ants or bees, and social mammals such as many primates including Man - as well as other mammals with differentiated social roles such as naked mole rats or meerkats).

The problem for the sustained survival of social animals over many generations is that individuals tend to evolve to enhance their personal reproductive success at the expense of the group - taking benefits from social living while avoiding the costs and duties of social living - thereby destroying the social structure.

The fact that social animals are known to have existed over many generations is evidence that his problem has been solved historically - and the underpinning mechanism is usually regarded to be kin selection (aka inclusive fitness) together with reciprocity (the mutual benefits of cooperation).

The difficulty with such individual level mechanisms as kin selection is that they must themselves evolve in a context where the spontaneous tendency is for adaptations to be lost - on top of the spontaneous tendency for kin selection and reciprocity to be damaged by spontaneous mutations. In other words it is very difficult to evolve a high level mechanism of social living on top of all the other layers of cooperation at sub-cellular and cellular levels - all of which are vulnerable to destruction by spontaneous mutations.

This is presumably one reason why social animals have been a late arrival on the evolutionary scene, in the past couple of hundred thousand years - however, once a stable and sustainable adaptation had arisen to enforce sociality, these animals have more-or-less taken over the earth by becoming the dominant species. Thus ants and termites dominate the tropical regions (in terms of biomass) while more recently humans have come to dominate the temperate zones.

Clearly sociality is a tremendous advantage - the difficulties are in evolving it, and sustaining it in the face of continued spontaneous mutations with each generation; and the tendency of sub-lethal deleterious mutations to accumulate generation-upon-generation; plus any environmental change and variety which is itself a consequence of the high adaptiveness of these species.

However, the very success of social animals, their dominance, would be expected to contain the seeds of destruction - since the conditions for free-riding and parasitism are greatly increased by the expansion in numbers and the relative autonomy from environmental constraints such as food supply and predation.

(This can be seen very clearly in modern human society, where the large surplus of modern economies above subsistence allows for unprecedented levels of parasitic behaviour by individuals, and also groups - such as bureaucracies.)

A successful social species can therefore find itself in the situation when the main proximate constraint on reproductive success is competition within the species - and this creates many niches for more-or-less parasitic and exploitative behaviours (the individual profiting at the expense of the group).

In the short-term, the fastest and most secure route to enhanced reproductive success is to exploit other humans (rather than cooperate with them) - and this would tend to destroy the social structure by reproductively favouring the least social individual animals.

Group selection entails that the group has an identity, that this identity must have integrity over time, and that it be transmissible between generations. This group identity must be able to sustain itself and should also be potentially further-adaptive to some extent.

Group identity needs to be of a cognitive and behavioural nature - in other words there must be strategizing knowledge and also some kind of reasoning from this knowledge. In sum, group selection requires a group identity; and group identity requires a teleology, aim or purpose; and that purpose should 'know' (with better than random probability) how to implement itself in individuals within that group.

This is probably the basis of the intense modern suspicion of and hostility to group selection - this idea that group selection entails something like a group purpose, memory and 'mind' - which superficially sounds like a non-biological, maybe even supernatural, kind of thing.
However, social animals are based on communications between networks of individuals, and the idea of conceptualizing the complex interactions of individuals in terms of being a type of 'computational' or 'cognitive' process is actually fairly mainstream - for instance in the theories of complex systems, the mathematics of chaos and complexity and elsewhere.

So, in principle, there is no reason to exclude the possibility that webs of complexly interacting social animals can be considered as higher level, group entities - which have a tendency to sustain and reproduce themselves.

Furthermore, these networks of communications fall into patterns, and these patterns may be self-sustaining and with a tendency to expand - so there is a potential mechanism for non-genetic inter-generation transmission.

In other words, the group-level entity is a pattern of communications which is both influenced by and also influences the communications (and behaviours) of the individual components of that patter: the individual organisms. And this pattern of communications will tend to fall into relatively stable forms, forms that resist change.

(Such a stability of forms is something which has cropped up in many areas of science over more than 2000 years - since at least the time of Aristotle with his elaboration of a finite number of archetypal 'forms' or relatively stable conformations into which all things will tend to 'fall; modern conceptualizations of the same basic idea include 'strange attractors' and 'morphic fields'.)

I do not see any fatal difficulty in supposing that relatively stable and 'cognitive' patterns of inter-individual, group communications would be transmissible between generations of social animals - given that these generations are overlapping (with new group members incrementally arriving and maturing, while others are leaving and dying - but without a break in the continuity of communications).

Such a concept of 'group mind' would have implicit purpose (survival and self-propagation) implemented by problem solving and strategizing properties including memory and intelligent processing.

Therefore, in principle, this group mind entity could identify problems among individuals within the group, and (to a significant extent) suppress selfishness at the individual level - also it could foresee (with better than random probability) the need for (or potential benefits from) certain types of individual which would be useful to the group survival and reproduction. Then individuals of this type might be induced to arise from the group - perhaps by the kind of developmental switching posited by Life History theory.

So, for the putative example of genius - it seems possible that the group mind might detect and appreciate the need for, or potential benefits from, an increase in the production of geniuses (i.e. those individuals characterized by what I have termed an Endogenous personality comprising a triad of high intelligence, intuitive thinking and inner motivation).

Having calculated that such individuals would probably be of value to the group - it seems possible that either the developmental trajectory of individuals might be directed towards becoming a genius - or more fundamentally that suitable pairs of individual parents (especially those characterized by high intelligence - low mutational load) might (perhaps by broadly 'epigenetic' means, by affecting gene switching, activation, suppression etc) lead to the sexual conception of more potential geniuses who are designed to benefit the group survival and reproduction, even when this tends to reduce the probability of reproductive success in the individual geniuses.

So this above scheme could, in broad brush terms, provide a group selection mechanism by which the group benefits of genius might be acquired when the group circumstances require, despite that many or most geniuses have below average reproductive success due to their energies and efforts being directed at non-reproductive, non-social goals.

Monday, 26 October 2015

Sexual selection has been done mostly by the bride's parents - i.e. middle aged couples - hence it is much more economically-rational, and culturally sensitive, than is generally supposed

Mate choice, throughout human evolutionary history, has been mostly done by parents, that is by middle aged people - and especially the woman's parents:


Therefore, there has not been much in the way of natural selection for women to be good at choosing their sexual partners or husbands - and it should not be surprising if modern women are in fact not good at this.

(Which, clearly, they aren't.)

This means that it is not a valid test of sexual selection in humans to ask young women to rate men for attractiveness - from an evolutionary perspective this is all but irrelevant.

If modern young women happen to prefer to choose 'hot' young men as sexual partners or husbands (charming men, dominant men, men with strong jaws and big shoulders and narrow hips in a V-shape, 'guns' or 'six pack' etc...) this kind of preference is highly likely to be a contingent and ephemeral cultural artefact - resulting from women's instinctive susceptibility to peer pressure, as amplified and distorted by the modern mass media.

The fact is that modern young women - instinctively speaking, in terms of evolved adaptations - haven't a clue about how to choose a good sexual or marriage partner! Indeed - why should they? since such preferences had little or no impact on human evolutionary history.

(Sex outside of marriage may lead to children being born, but in the past - in a context of average child mortality rates of more than a half - these children lacking the support and resources of a long-term marriage type relationship would almost certainly have died before maturity, and/ or been unhealthy and low in status.)

To test for what traits have been sexually selected, a far better test would be to ask middle aged parents to choose what kind of men they would want as a husband for their daughter - because that decision is the one that was under strong selective pressure over many generations.

I think it would be found that parents chose - on average - rationally, on the basis of whatever (unglamorous!) traits best indicated a faithful, steady and good provider for their grandchildren.

In other words, sexual selection as it actually was would quite often (in many types of economy - although not all situations) favour 'Dads' not 'Cads' - and if their daughters found the Dad type of man was not much of a turn-on... well so what! There are more important things when life is harsh and very few children survive to maturity.

Under most ancestral conditions, the sexual preferences of young women would not make any difference - one way or the other.

Reference: Apostolou, M. (2012). Sexual selection under parental choice: Evidence from sixteen historical societies. Evolutionary Psychology, 10, 504-518. This paper makes clear why, in traditional societies, Dads need not fear spousal infidelity with Cads. Apostolou looked at the level of punishment when a woman is discovered to have committed adultery. Three levels were coded: No punishment/ light punishment; moderate (!) punishments including beating and divorce; severe punishment such as beating to death. No punishment/  light punishment were found in 5 out of 54 of agropastoral societies; while severe punishments for adultery were found in about two-thirds of these societies - a large majority of 35 out of 54.

Sunday, 18 October 2015

The relationship between Asperger's syndrome and Genius

Asperger's syndrome arose to public awareness very quickly during the 1990s, and without a clear or coherent underlying basis. It has remained as a kind of short-hand way of describing boys and men of high intelligence who are socially uninterested but instead focus upon abstract, nerdy or geeky topics.

It has been noticed that many of the archetypal geniuses of the past seem to be, more or less, of this type: for example, Alan Turing was depicted as such in the recent movie The Imitation Game - and this links Asperger's to the cult English actor Benedict Cumberbatch's other famous role as Sherlock. Turing was, of course, a real-life Aspergery-genius; and Sherlock is a fictional example.

And the most famous media depiction of Asperger's is probably Sheldon Cooper in the sit-com Big Bang Theory - and this character refers to himself, and is often referred to by others, as a 'genius'. Much of the humour in the series comes from Sheldon's ineptness in social situations - he is blind to, as well as uninterested by, other people's intentions and emotions; he takes things literally instead of as they were meant.

But there is an ambiguity in the way that 'genius' is used in popular culture. Strictly, the term ought to mean creative intelligence - as seen in such Asperger's types as Turing, Isaac Newton and Kurt Godel; but it is perhaps more often used in popular culture to mean precocious ability in childhood; as when a young teenager excels in university admissions-type examinations.

Precocious intellectual ability is usually a predictor of high adult intelligence; and high adult intelligence is necessary to creative genius - but it is not sufficient. Most precocious children do not turn-out to be creative geniuses - merely adults of higher than average ability.

But some precocious children do turn out to be creative geniuses - the philosopher John Stewart Mill was a well documented example; and DNA structure discoverer James D Watson was notably precocious - appearing on a radio quiz for smart children, attending the elite University of Chicago at 15, and getting his PhD (supervised by a Nobel Laureate) at 22.

On the other hand, Watson's co-discoverer Francis Crick shows that some geniuses are not at all precocious, but on the contrary are late developers - Crick went to his second choice university, got a second class degrees, started and dropped out of two PhDs and changed fields's three times when in his mid thirties he finally found 'his problem' and became one of the greatest and most creative biologists of his generation. Einstein was also of this late-flowering type, although less extreme than Crick.

So preciosity cannot be equated with genius.

As well as high intelligence, genius also requires a personality type which I have termed the Endogenous personality


This is an intuitive, inner-motivated type of personality - and people who get called Asperger's are usually inner-motivated but they are not usually intuitive; indeed perhaps they are stereotypically ultra-logical and mistrusting of intuition.

And there is an ambiguity in the way that Asperger's is defined and discussed. Sometimes it is seen as a person with a deficit in social intelligence; at other times as someone with a lack of interest in social matters.

The difference can be important, because the genius is primarily someone who is (relatively) uninterested in social (including usually sexual) things - mainly because he is so intensely interested in his 'work' - is focused and concentrated on his work, pours most of his effort into work. The genius is best understood as specialized for creativity, rather than as merely having a deficit (although, in a sense, specialization in one area does almost inevitably show-up as at least a relative deficiency in other areas). 

Sometimes the Apserger's person is depicted at lacking in emotion - but if so, this would be fatal to genius.

Because the genius absolutely requires emotion in order to be creative at the highest level: he uses emotions in evaluating. (Intuition can be defined as using all aspects of psychology in thinking - not just reason and logic - therefore necessarily including the emotions.)

In sum: unemotional = uncreative; and the reason is that the emotions are necessarily used in creativity: creativity requires intuition; and emotions are part of intuition.

Therefore a Mr Logic or Mr Spock kind of person cannot be creative - and the same applies to a personal labelled as Asperger's who is lacking in emotion - he will not be able to use intuition.

Furthermore, lack of emotion also entails lack of inner motivation - it is our emotions which motivate us; and anything which blunts or reduces emotions will be demotivating (for example, the antipsychotic/ neuroleptic drugs are horribly demotivating, or more weakly the SSRI antidepressants).

And geniuses must be highly motivated if they are to accomplish work at the highest level.

In conclusion - the genius will often be an Asperger's type of person, in the sense that he will tend to be relatively un-interested by social and sexual relationships; as a side effect of being internally driven to focus and work on that which is his creative destiny (e. Shakespeare's poetry and plays, Rembrandt's painting, Beethoven's music, Einstein's physics - or whatever it may be).

So the true genius will usually appear to be Aspergers-like to the normal person.

On the other hand, most people with Asperger's syndrome are not geniuses (not even partial or potential geniuses), even when they have exceptionally high intelligence - because they lack the intuitive style of thinking which is vital for real creativity.


Here is some further background reading, to explain the reason why Asperger's syndrome and Genius share the trait of lack of interest in social matters.

The following passage comes from the chapter "Identifying the Genius" from my forthcoming book The Genius Famine - by Ed Dutton and Bruce G Charlton, University of Buckingham Press (2015, in the press).

The Asocial genius

Humans are social animals: most Men see the world through social spectacles.
But a genius is not like this. The genius does not have a single, stereotypical, positive personality type (because Endogenous personalities are very various in terms of traits such as likeableness, helpfulness, and personal warmth) – but geniuses are characterised by not being primarily social animals. A genius is one whose main focus and motivation is not social, nor sexual; but instead abstract, asocial – whether artistic, scientific, technical, or whatever it may be.
Could it then be that the genius uses for abstract thinking, those brain-systems which in most people are used for social intelligence? That in the genius the social intelligence system is wired-up to internal stimuli instead of to social situations? It seems that the genius deploys the social intelligence parts of the brain for other purposes – and that therefore the usual spontaneous motivation and attention that goes to social material is instead – automatically – being harnessed and deployed to deal with other and inner-generated material. This seems to us very likely; although such aspects of brain structure have not yet been reliably measured. But given that the genius brain seems to be hard-wired for both creativity and intelligence; it is plausible that this may be made possible by functional re-deployment of at least some aspects of social/ sexual circuitry.
So, it is not that geniuses lack social intelligence (the genius is not ‘autistic’ in the sense of having a deficit or defect in social intelligence); rather that geniuses have all the ‘equipment’ necessary for social intelligence, but are ‘wired-up’ to use their social intelligence for other and not-social purposes.
Specifically, the genius’s social intelligence may be wired-up to internally-generated material (instead of attending to actual people in the environment and from memory). The spontaneous interest and concern with ‘‘other people’’ that is characteristic of most people is, in the genius, directed to whatever ‘abstract’ subject the genius has a vocation-for.
Another way of thinking about this is that the genius may be able to deploy extra ‘‘brain power’’ in problem solving, by ‘‘co-opting’’ the brain regions normally used for social intelligence. And not only brain power – but the distinctive ‘‘theory of mind’’ mode of thinking which characterises social intelligence. So the genius often thinks about ‘‘his subject’’ in a social-like way – as a world populated by entities with motivations and dispositions and each having a purpose.
Social intelligence could be much of what is creative about creativity; because to think about abstract things ‘anthropomorphically’ with social intelligence, or animistically as if they were sentient social agents, perhaps opens-up a new and probably more creative, intuitive and flexible way of thinking.[1]
The Endogenous personality also has very high intelligence. This may be apparent through good exam results in a ‘g’-loaded evaluation, but may require formal intelligence testing to detect, if the individual has either suffered from poor or absent education, or else lacks the conscientiousness to apply himself to his studies. And sometimes intelligence tests won’t do justice to the genius’s abilities.
That the intelligence of the Endogenous Personality can sometimes not be identified in a conventional way is of crucial importance. Often, the genius will have extremely pronounced abilities in one area of intelligence – such as verbal intelligence – but will be less skilled in other areas.

Einstein, for example, had such high mathematical abilities that he developed an original proof of Pythagoras’ theorem at the age of 12. However, his linguistic abilities were so deficient that he failed the entrance exam for the Federal Institute of Technology in Zurich.[2] Consequently, though an IQ test can capture general intelligence it will not necessarily be able to capture genuine genius.

So, the Endogenous personality may be recognized not just by their relative autonomy – that is, their lack of need for social validation and consequent lack of interest in social and sexual matters – but also by their high intelligence and positive motivation to do (or to find) ... whatever it is that they are equipped by their nature to do.

[1] Charlton, B. G. (2000). Psychiatry and the Human Condition. Oxford: Radcliffe.
[2] Miller, A. (1999). Albert Einstein. In M. Runco & S. Pritzker (Eds). Encyclopedia of Creativity. New York: Academic Press.

Thursday, 8 October 2015

Rate of deleterious mutations per generation, expected decline in fitness per generation - estimates from Michael Lynch

From Michael Lynch. Rate, molecular spectrum and consequences of human mutation. PNAS 2010; 107: 961-8. 

What is the likely magnitude of the per-generation loss in human fitness caused by recurrent introduction of deleterious mutations? From the present results, we infer that an average human gamete acquires approximately 38 de novo base-substitution mutations, approximately three small insertion/deletions in complex sequence, and approximately one splicing mutation. Transposable-element insertions, microsatellite instabilities, and segmental duplications and deletions of total or partial gene sequences will almost certainly sum to several additional events per gamete, so it is likely that an average newborn acquires a total of 50 to 100 new mutations at the diploid level, a small subset of which must be deleterious.

The net fitness consequences of human mutations remain unclear and will likely continue to be a major challenge, but some general arguments allow an order-of-magnitude assessment of the situation. Using rather different approaches, Yampolsky et al. and Eyre-Walker et al. have derived similar estimates of the distribution of fitness effects of new amino acid altering base-substitution mutations: approximately 11% cause fractional reductions in heterozygote fitness with s < 10−5, 12% with 10−5 < s < 10−4, 50% with 10−4 < s < 10−2, and 27% with s > 10−2, with an overall average selective disadvantage of approximately 0.04. Only approximately 1.5% of the human genome consists of coding DNA and approximately 25% of coding sites are silent, so we expect approximately 0.86 novel amino acid altering mutations per newborn. Approximately 5% of such mutations will lead to nonsense mutations, many of which will likely be in the category of s > 10−2, but the remaining 95% will be missense in nature, with deleterious fitness effects averaging approximately 4% or less according to these results. Thus, with a complete relaxation of natural selection, the expected decline in fitness associated with mutations in coding DNA alone appears to be on the order of 1% to 3% per generation.

Less clear is the added contribution from other forms of mutations. The vast majority of point mutations reside outside of coding regions (on the order of 40 per gamete), and it is likely that most of these will have very minor fitness effects, with average s almost certainly << 10−2. Nevertheless, Eöry et al. make a compelling case that approximately 4% of intergenic, 15% of UTR, and 22% of silent sites are under weak purifying selection in humans, which is consistent with the arguments presented above for base-composition selection. Most major deletions and splicing mutations are probably highly deleterious, as they will generally render their host genes nonfunctional. Most transposable-element insertions and gene duplications appear to be at least weakly deleterious; the average deleterious effects of such mutations are likely to be at least 1% per event, and as noted earlier, at least one such event is likely to arise per zygote per generation. Thus, although there is considerable uncertainty in the preceding numbers, it is difficult to escape the conclusion that the per-generation reduction in fitness due to recurrent mutation is at least 1% in humans and quite possibly as high as 5%.

Although such a mutational buildup would be unnoticeable on a generation timescale, over the course of a couple of centuries (approximately six generations), the consequences are likely to become serious, particularly if human activities cause an increase in the mutation rate itself (by increasing levels of environmental mutagens). A doubling in the mutation rate would imply a 2% to 10% decline in fitness per generation, and by extension, a 12% to 60% decline in 200 years... 

Unfortunately, it has become increasingly clear that most of the mutation load is associated with mutations with very small effects distributed at unpredictable locations over the entire genome, rendering the prospects for long-term management of the human gene pool by genetic counseling highly unlikely for all but perhaps a few hundred key loci underlying debilitating monogenic genetic disorders (such as those focused on in the present study)…