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 (ie. 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)…