Recently, I heard the latter portions of the radio version of a play, “Lucy” by Damien Atkins, relating to autism and produced by L.A. Theatre Works. “Lucy” was originally performed and reviewed as long ago as November of 2007, but I was not aware of it until I encountered the production for radio about one week ago. The plot revolves around a couple (Vivian and Gavin) with a daughter (Lucy) who is 13 years old and has a severe form of autism. Of particular interest for the EMR readership is how Lucy’s mother, Vivian, views the relationship between the direction of human evolution and the prevalence of autism and the need for individuals with autism to receive therapy.
According to one review of the play (Siegel and Siegel, 2007), a key plot point that I missed in the earlier portion of the play was that after Lucy was born, Vivian gave her to Gavin, the father, to raise so that she could pursue her professional career as an anthropologist. Of high relevance to the playwright’s apparent message as embodied by the play, Vivian is presented as both brilliant and socially awkward, i.e. similar in key respects to her daughter.
The plot moves forward by virtue of Gavin’s request that Vivian take Lucy for one year so that he can deal with personal matters that were either not specified or were alluded to before I began listening. Based on two reviews of the play (Siegel and Siegel, 2007; Zinoman, 2007), the early scenes involving the relationship between mother and daughter portray Vivian as struggling to communicate with Lucy, who exhibits limited verbal ability.
Near the end of the play, when the mother plans to move to Africa for her work as an anthropologist, the father objects. He also disagrees with the mother about the therapy that Lucy has been receiving. The father favors continued treatment but the mother objects. In the ensuing argument between the parents, the mother suggests that Lucy is not merely fine as she is, but that she is actually more evolved than other children who do not have autism. Although it is only implicit, the suggestion appears to be that individuals with autism-related attributes will be favored by natural selection.
After the end of the performance, the host for the radio program interviewed the eminent UCLA neurogeneticist Daniel Geschwind. I have high respect for Dr. Geshwind’s research into the genetics of autism and have briefly corresponded with him some years ago.
Consequently, I was quite disappointed when Dr. Geschwind, while refusing to directly endorse Vivian’s highly dubious thesis that individuals with autism are evolutionarily superior to individuals who do not manifest the autistic profile, sort of obliquely granted this questionable idea some credibility. Dr. Geshwind noted that when he has a serious writing project to complete, he prefers social isolation. This observation, whatever Geschwind meant by it, could be interpreted by some to suggest that it can be advantageous to be “autistic” or “autistic-like” if, like Vivian, you aspire to major accomplishments.
Statements about the advantages of traits often linked to autism (such as intense focus on one or a few subjects of interest) have the potential to arouse strong responses from people with diverse interests, including those involved in what can be called the autism rights movement. I am offering no definitive broad-based value judgment about attributes associated with autism because the net impact of any given trait can vary widely with circumstances intrinsic or extrinsic to an individual, affected or otherwise. But I am wary of assertions about the overall superiority of autism-associated traits because I have previously seen how misleading they can be (Greenspan, 2010).
While some may praise the playwright, Damien Atkins, for posing such a provocative notion, it is only tenable in the absence of much insight into how evolution by natural selection operates. Given the difficulties in social interaction associated with autism, it would not be expected that individuals affected by autism would on average have greater reproductive fitness or genetic success than individuals without autism.
Evidence consistent with the above expectation has been published (Power et al., 2013). The study was based on a cohort of over two million individuals in Sweden who were born between 1950 and 1970. For males affected with autism, the fertility ratio was decreased more than 70% compared to the general population. In addition to the reduced reproductive fitness of affected males and females (fertility ratio decreased about 50%), their genetic success was probably also reduced since brothers of affected individuals had a modestly reduced fertility ratio (5-6% reduction from general population average) and sisters of affected individuals had a fertility ratio comparable to the general population average.
Another recent study suggests that parents of children with autism tend to have fewer children than parents who do not have children with autism (Hoffmann et al., 2014). These results, in conjunction with those cited directly above, argue strongly against any notion that manifesting the behaviors associated with autism will provide an evolutionarily relevant advantage.
References
Siegel B, Siegel S. Sensational performances by Lisa Emery and Lucy DeVito highlight this rich new play that seamlessly combines science and theater. November 1, 2007.
http://www.theatermania.com/new-york-city-theater/reviews/11-2007/lucy_11967.html (last accessed on 10/10/14)
Zinoman J. An anthropologist evolves with help from her autistic child. November 2, 2007. http://www.nytimes.com/2007/11/02/theater/reviews/02lucy.html (last accessed on 10/09/14)
Power RA, Kyaga S, Uher R, MacCabe JH, Långström N, Landen M, McGuffin P, Lewis CM, Lichtenstein P, Svensson AC. Fecundity of patients with schizophrenia, autism, bipolar disorder, depression, anorexia nervosa, or substance abuse vs their unaffected siblings. JAMA Psychiatry. 2013 Jan;70(1):22-30. doi: 10.1001/jamapsychiatry.2013.268. PubMed PMID: 23147713.
Hoffmann TJ, Windham GC, Anderson M, Croen LA, Grether JK, Risch N. Evidence of reproductive stoppage in families with autism spectrum disorder: a large, population-based cohort study. JAMA Psychiatry. 2014 Aug;71(8):943-51. doi: 10.1001/jamapsychiatry.2014.420. PubMed PMID: 24942798.
Greenspan, N.S. Autism conceptualized: “cloud vs. “spectrum.” The Huffington Post, May 25, 2010. http://www.huffingtonpost.com/neil-s-greenspan/autism-conceptualizing-au_b_586546.html (last accessed on 10/10/14)
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The argument that people with autistic traits will reproduce less is not valid. The statistics given in the article refer to people with an autism diagnosis. Since we know that the effects of autism range from mild to severe, it could be imagined that only those individuals with severe symptoms will receive a medical diagnosis. That fraction of the population will surely have a lower fertility ratio. However, it is still unproven that people who are ‘ “autistic” or “autistic-like” ‘ will have decreased fertility.
8/06/16
Robert, you assert on the basis of zero evidence, that the “argument that people with autistic traits will reproduce less is not valid.” On the other hand, the thesis in my post at evmedreview.com from October 10, 2014 (http://dev-evmedreview.pantheonsite.io/wrong-with-geschwind-dubious-ideas-about-autism-and-human-evolution/) concerned the claim by a character in “Lucy”, a play by Damien Atkins, that the direction of human evolution is such that over time increasing proportions of individuals will exhibit autistic traits. My key point is worded quite cautiously:
“Given the difficulties in social interaction associated with autism, it would not be expected that individuals affected by autism would on average have greater reproductive fitness or genetic success than individuals without autism.”
In using the phrase “affected by autism” I was referring to those individuals with a diagnosed condition. Even if one extends the range of reference to individuals who are not formally diagnosed but exhibit some traits associated with autism, there is no reason to expect that these people would, on average, procreate more than others. In fact, given that even individuals in this population will in many cases have deficits of one sort or another in social skills, it be reasonable to expect reproductive fitness no better and possibly less than the population average.
Furthermore, the data I cite indicate not merely that individuals with diagnosed autism have reduced fertility, but that parents and male siblings of those individuals also have reduced fertility. Female siblings had fertility comparable to, but not better than, individuals in the general population.
I did not claim that anyone with an autism-associated trait would necessarily have fertility below that of the population average, although that remains plausible. At this point, I see no justification for revising my argument.
On the other hand, evolution works on alleles, not on individuals. So maybe the question is not “do an autistic person have less/more children than average” but “are ASD risk alleles under positive selection”. They are. https://doi.org/10.1371/journal.pgen.1006618
I also see two problems with ASD research in general.
1. There are two kinds of ASD – familial and sporadic. Treating these in research as one can lead to false conclusions, especially if we speak about evolution.
2. High-functioning ASD persons often do not have a formal diagnosis. So the stats are usually based mostly on low-functioning individuals.
I think we can’t say it’s “better” to be an autistic person, especially low-functioning. But we can say it’s better to have ASD alleles, of course not all of them in one person. And as we speak about the evolution of population, we can look at other social species. It’s good to be social when you are for example an ant or a bee, right? But not all bees are social. Those who build the beehive aren’t. And these are genetically different – they have one of the human ASD-risk allele.
Evolution can be defined with respect to allele frequencies, but the thesis expressed in the play by Vivian, who was the mother of the nominally central character, Lucy, was about people with particular phenotypes, not genotypes. My point was specifically that, on average, individuals with autistic phenotypes are not likely to be favored by selection.
As for autism-related alleles being under positive selection, that is likely not true for the majority of alleles or other genetic variants that have so far been implicated as causes of neurodevelopmental disabilities that are associated with clinical manifestations typical of autism. Most of these alleles are rare or even unique. Some are de novo and others are private mutations that may be of recent origin.
Because the sickle allele of beta-hemoglobin is favored by selection in areas where falciparum malaria is endemic, it does not make individuals with sickle cell disease favored by evolution or “more evolved.” I am aware that the pertinent inheritance patterns in autism may not typically be the same as in sickle cell disease, but the point still applies.
By the way, as noted in my article, Lucy is described in the play as having a fairly severe form of autism and is only modestly verbal. If Lucy is not especially “high-functioning,” as that term is typically used, it is made more likely that she has one or more autism-associated alleles that are not being positively selected. Nevertheless, Vivian appears to suggest that individuals like her daughter, Lucy, are preferred by evolution and therefore the future of humanity in some sense. I regard this thesis as highly doubtful.
The distinction between familial and sporadic forms of autism may be useful, but it is a major oversimplification. Some individuals with autism have two or more contributory genes (oligogenic etiology), and these genes can be mixtures of common and rare alleles at different loci. Of course, you are correct that averaging over heterogeneous patient cohorts can lead to faulty inferences in this context and more generally in the study of clinical conditions.
The term autism (or “ASD”, which I prefer not to use) is now so broad as to render it not very useful. Some high-functioning people who claim they have autism but lack a formal diagnosis may not merit a diagnosis. Diagnoses are most useful when they convey information that is useful for treatment, prognosis, or at least give the patient and/or family members insight about why the condition has the manifestations it does. Therefore, it makes sense to focus diagnosis on those individuals who, at least in many cases, actually need medical and/or other types of assistance to lead decent lives because they are not self-sufficient.
You say: “I think we can’t say it’s “better” to be an autistic person, especially low-functioning.” That was my point in the commentary, in contrast to the implied view of the playwright.
You then state: “But we can say it’s better to have ASD alleles, of course not all of them in one person. And as we speak about the evolution of population, we can look at other social species. It’s good to be social when you are for example an ant or a bee, right? But not all bees are social. Those who build the beehive aren’t. And these are genetically different – they have one of the human ASD-risk allele.”
It may not always be better to have autism-associated alleles depending on both the genetic and environmental context. These alleles may have effects of which we are currently unaware due to epistasis or gene-environment interactions.