I thought you'd like this study, lol - schizophrenia is largely genetic, schizotypy is associated with schizophrenia, schizotypy is related to creativity, creativity is related to sexual success - therefore sexual success of schizotypy maintains the scizophrenic genes...
Heheheh... yeah this is a nice paper to look at. It isn't as flawed as many EP papers, but that makes it good to show where methodology works and where it doesn't. That reasoning though, yikes. Reminds me eerily of Monty Python's Holy Grail.
I apologize in advance for making minimal quotes from the paper, but it is in pdf and I hate transcribing long sections or mutiple sections. I'll quote sections I believe are necessary and we can mention others in the future as needed.
Okay first for the positives.
1) Unlike many EP papers, this addresses a condition which is shown to have a genetic component. Other papers (such as the whr study) substitute correlation to population for actual evidence of genetics. In this case the genetic component is a predisposition to schiz, it can be seen branching via reproduction in the population, with mediating/provoking effects based on environmental factors.
2) They use a method for measuring schizotypy which is valid so that a (reasonably identified) genetic trait is the actual target for comparison to other variables.
3) They are not exactly seeking why a trait was selected for in humans, but rather given its patently negative effects, why it has not been deselected. There is a difference. A neutral characteristic will arise and remain without any adaptive advantage, but a negative characteristic would (reasonably) be expected to diminish which it appears is not happening.
Now for the problems.
THEORETICAL
1) They do not actually deliver a problem for stability of schiz within populations. The numbers are small (1%) and while they cite evidence full blown schiz can drastically reduce probability of reproduction, this does not pose an "evolutionary puzzle" when they go on to show that genetic predisposition is not synonymous with full blown schiz (it should be noted that later in their paper they reveal it is predominantly one manifestation of schiz which may have the deleterious effects)...
Reduced fitness in sufferers would be expected to lead to the disappearance of the heritable traits predisposing individuals to the condition. The fact that this does not appear to happen has lead many commentators to speculate that there must be other, beneficial effects of the traits, most probably manifest in healthy relatives...
Why would those carrying genes predisposed to schiz have to have beneficial effects, just because those who end up manifesting schiz do not reproduce as much? As long as there was no reproductive bar to those with such predisposition it is possible for schiz total numbers to remain stable. Those predisposed produce a consistent number of offspring, with a consistent minority that do not reproduce (or reproduce less). Given the nature of genes to actual schiz (it is dependent on environmental factors) there would be no reason for it to disappear, only to reach an equilibrium. Indeed given the neutrality (much less the positive traits they argue for within their paper) of schiz dispositive genes, they could easily increase throughout populations, resulting in positive schizophrenic numbers over time.
2) They do not address another, perhaps more obvious, puzzle. Why would %'s remain stable over time and across cultures, when there have been drastic improvements in health care (including mental health) over time and across cultures as well as differences in how artistic creativity is rewarded across cultures? I am personally skeptical of this claim given the relative newness of such testing (and knowledge of schiz) much less its possible testing across all cultures. But I am going to assume their cited studies are correct for now, and point out it poses a problem. Reasonably... evolutionarily... we should see differences.
3) They do not bother to investigate this phenomena further along epidemiological or demographic lines. How is it physically being maintained? By what populations? Instead they ASSUME they are correct that it is healthy schiz-disposed types manifesting some beneficial trait, and ASSUME that it could be based in artistry, in order to jump to a totally separate EP SPECULATION (which itself needs more investigation), and suggest that might provide an answer. In a way they attempt to kill two birds with one study. However that is an error. It is possible for there to be other answers for why schiz-disp gene carriers do not disappear, so finding that creative types might have more reproductive success is an extremely dubious piece of evidence in order to reach a conclusion that it is a likely answer. (One example of another explanation, is that families or groups with schiz-disp genes form reproductive strategies of having more children because some are or will likely become ill.)
METHODOLOGICAL
4) The study was small in scale and completely unicultural. There was no chance of weeding out cultural influences regarding how creativity and artistry in specific is treated within our culture. Within their own results section they mention that...
It is possible that these relationships arise because the specialist artist and poet groups who were recruited, and who are high in unusual experiences... have different lifestyles than the general population.
While the rerun of results within this specific study showed little difference, the point above still stands not just for artistic groups within other cultures but the inherently different lifestyles within other cultures.
5) The study was a self-assessment test. These are problematic in and of themselves, but I will lay that to the side for this discussion. I am only going to point out that "creative" types may very well skew responses, particularly regarding sexual partners or other experiences culturally linked to artists. The same may be said for people who actually have "impulsive non-conformity" issues.
6) The study focused on numbers of partners. While it states that this is a valid measure of mating success (quantity=success) in some studies, that directly contradicts other EP studies which argue longterm monogamy is an evolutionarily driven psych strategy (quality over quantity).
I will leave that inconsistency alone for now to focus on the more important point that sexual partners does NOT equate to children at all, even if potential is theoretically higher. If the issue is actual sustained numbers, potentials to have children are wholly useless for extrapolation. Interestingly they used a major cultural bias within this part of the test. From their methods section...
The questionnaire also provided information on mating success in the form of the following questions: 'Since you were 18, how much of the time...' and 'Since you were 18, how many different partners have you had...?'
Why would they restrict age at all? As long as one is capable of being pregnant or causing pregnancy, and the issue is creating offspring, that is an artificial construct which may skew results of a study. This would particularly be an issue if psych factors associated with schiz could affect when people become sexual active.
ANALYSIS
7) The first thing to note is their analysis regarding number of children...
For number of children, the only significant association with schizotypy was with cognitive disorganization... {it was negatively associated}
Given that their study assumed that number of partners should match reproductive success (they even begin to refer to it AS mating success) the fact that number of children does not correlate to number of partners is problematic. That the results hold essentially a contradictory correlation is devastating. Yet this rather obvious point is never discussed at all! The results of this study in fact challenge the citations they used to make their assumption. Number of partners here did NOT at all correlate with number of children and so such assumptions cannot be made. This alone should have killed the study as being conclusive.
8) In Figure One they show how creativity relates to numbers of partners. On can clearly see that artistic activity alone does not have an effect. Effects are only seen as artists are engaged in "serious" or "professional" artistry. The authors attribute this to a hypothesis that artistic creativity functions as a mating display, with yet another hidden assumption that serious or professional artists are more creative. While that may be true they do not show any analyses to discount, nor do they bother to discuss, the equally viable (and to my mind more obvious) possibility that success or fame is a factor in attracting partners. It certainly cannot be assumed that success and fame are objectively correlated to creative impulse and output. But strangely they appear to have done that very thing within materials and methods...
Obviously, information on quality of the participants' work was not directly available. However, it is assumed that increasingly serious engagement with the activity is generally correlated with increasing quality and visibility of work.
One generally assumes that only the best and brightest will get elected to lead nations in a free democratic state, and the more they spend time in office the better they will get, but that is not the case. I have no idea how that assumption was allowed to pass by any peer review as acceptable. Heck, even if I were to accept quality as correlated to success or fame, what does quality have to do with drive? Unless they are also assuming that artistic passion translates to artistic talents I am at a loss as to what any of this has to do with schiz-disp genetics which can only produce drive.
Here is an example: the Baldwins are all artists. I cannot say which has the greatest drive, nor that the one that has the greatest drive actually has the greatest talent, or the one that has the greatest talent has the greatest fame. The one thing I can be pretty certain of is that an equally talented though unrelated actor may never reach the same level of fame, not to mention access to the same number of sexual partners, as they do because one of them became famous first.
9) Nowhere did I see a discussion of how their results actually exhibit a statistically relevant conclusion that it is creativity as an attractor which keeps schizophrenia stable within a population. What numbers should I have been expecting to see that would disprove their theory because it would not have been enough?
Conclusion...
I think I'll leave it right there for now. It is some of the major problems I see and which characterize pop EP methodology.
What this appears to tell me (at best) is that talented or "busy" artists within Britain have greater numbers of partners. Separately some forms of schizotypy may have some correlation with numbers of partners, but to what degree such that it addresses the initial "puzzle" I have no idea. At worst it calls into question some of their supporting citations as well as ignoring a more obvious conclusion that success alone might be a factor in finding partners, and so confound making statements about creativity from these results.
I apologize if my ending is weak, but I am writing after 1:30am. Hopefully it suffices.
holmes
"What you need is sustained outrage...there's far too much unthinking respect given to authority." (M.Ivins)
™ Version 4.2