Wednesday, February 23, 2011

The “Solitary Forager” Hypothesis of Autism:

I created a new web page recently to post my “theory of autism.” The theory attempts to explain why autism exists by elucidating its evolutionary history. Consistent with Simon Baron-Cohen’s systemizing theory of autism and with Temple Grandin’s positions, I see most autistic individuals as intelligent and autism as having compensatory advantages. Clearly, sometimes autism is accompanied by disease states, but the psychological "symptoms" of autism are seen here as attributes that would have benefitted a solitary forager (see the table at the bottom).

"To the extent that neurotypical individuals can be thought of as social foragers, autistic individuals can be thought of as solitary foragers."

There has been a lot of recent speculation and controversy over autism and what its existence "means.” A number of theoretical articles have been written on the subject such as the “Neanderthal theory of autism,” the “neoteny theory of autism,” the “extreme male brain theory,” the “imprinted brain theory” and the argument that autism is the “next stage in human evolution.” These are all interesting interpretations some of which may have some explanatory utility. I think that the “solitary forager hypothesis,” however; explains autism from the perspective of natural history.

Please take a look at:

You can also find an early and unabbreviated version here:
Abstract:This article reviews etiological and comparative evidence supporting the hypothesis that some heritable genes associated with the autism spectrum were naturally selected and represent the adaptive benefits of being cognitively suited for solitary foraging. The systemizing theory of autism is extended here and people on the autism spectrum are conceptualized as ecologically competent individuals that could have been adept at learning and implementing hunting and gathering skills in the ancestral environment. Upon independence from their mothers, young autistic individuals may have been psychologically predisposed toward a different life-history strategy, common among mammals and even some primates, to hunt and gather primarily on their own. Many of the behavioral and cognitive tendencies that autistic individuals exhibit are viewed here as adaptations that would have complemented a solitary lifestyle. For example, the obsessive, repetitive and systemizing tendencies in autism, which can be mistakenly applied toward activities such as block stacking today, may have been focused by hunger and thirst toward successful food procurement in the ancestral past. 

Individuals on the autism spectrum share a variety of behavioral traits with solitary species. Both solitary mammals and autistic individuals are low on measures of gregariousness, socialization, direct gazing, eye contact, facial expression, emotional engagement, affiliative need and other social behaviors. The evolution of the neurological tendencies in solitary species that predispose them toward being introverted and reclusive may hold important clues for the evolution of the autism spectrum and the natural selection of autism genes. Solitary animals are thought to eschew social contact as part of a foraging strategy often due to scarcity and wide dispersal of food in their native environments. Similarly, it is known that, due to frequent and prolonged dry spells, the human ancestral environment was often nutritionally scarce as well, and this may have driven human parties to periodically disband. Inconsistencies in group size must have led to inconsistencies in the manner in which natural selection fashioned the social minds of humans, which in turn may well be responsible for the large variation in social abilities seen in human populations. This article emphasizes that individuals on the autism spectrum may have only been partially solitary, that natural selection may have only favored subclinical autistic traits and that the most severe cases of autism may be due to assortative mating. This solitary forager hypothesis of autism is explored in the context of
anthropology, comparative neuroscience, epidemiology, evolutionary biology, neuroethology, and primatology.


Table 1: Behavior in autism, then and now

Trait or Symptom
Psychological  Consequences
Implications for Moderns
Implications for Solitary Foragers
High systemizing ability
A tendency to systematically explore the laws governing nonsocial processes
Eccentric or narrow but substantial knowledge and skills
An impetus guiding the acquisition of food procurement techniques
Obsessive, repetitious tendencies
Perseveration in behavior and thought
Repetitious play and need for sameness
Order, structure and autonomous self-regulation
Gaze aversion and absence of shared eye contact
Minimal eye contact and diminished attention to the faces of others
Unfortunate social hurdle
Instinctually prepared not to challenge or provoke conspecifics
Low oxytocin
Reduced social interest, learning and expressiveness
Unfortunately hindered social cognition
Programmed for a socially impoverished environment
Anomalies in anterior cingulate cortex, orbito and medial frontal cortex
Reduced social learning, capacity for empathy and affiliative need
Hindered social integration
Decreased reliance on others
Amygdala hyperactivity
Potentiation of innate and conditioned fears
Excessive anxiety and withdrawal from social world
Healthy caution, and fear of unfamiliar conspecifics
Hippocampal hyperactivity
Hyperaccessibility of contextual and episodic information
Proficiency with spatial tasks and contextual memory
Skill in tests of spatial intelligence


  1. Thanks for this fascinating analysis. It adds to my own work on "Autism and creativity" on which I have been doing research for the past twelve years? It started with a hypothesis on a link betwenn autistic savant art and late Palaeolithic decorated caves paintings and drawings.
    Later on I developped a broader analysis including as creativity sources, several autism related cognitive differences (as Francesca Happé says, rather than disabilities)

    Indeed some autistic traits generaly considered detrimental can be seen in a very different way and be at the origin of creativity.
    See my paper on my website:

    Under that link look for the section "Autism" and a paper entitled :

    "Autism and Creativity: A Different view of Autism
    Competences and Potentials alongside Disabilities"


    Most publications on autism emphasise the disabling and handicapping aspects of autism or the medical and psychological basis and consequences of autism. But not all characteristics of autism have negative impacts on the lives of individuals who have autism. Some peculiarities of autism can indeed prove to have positive effects, provided that they are identified as such and nurtured through an educational program and used to broaden the scope of interests of these individuals.

    Among those positive aspects of autism one should here distinguish exceptional talents on the one side and on the other side, otherwise well known autistic functioning which can in some cases have positive effects on the expression of special abilities. These should be used as leverage for the development of social skills, without which the less positive
    characteristics of autistic behaviour will hide all the positive aspects benefits.

    I will analyse exceptional talents in drawing, painting, music, languages or calculation and mathematics found among individuals with autism. We will analyse how some of the characteristics usually seen as negative in autism, such as social abilities deficits, “theory of mind impairment”, lack of central coherence, repetitive behaviours and echolalia may also be seen more positively. We will then see how all these aspects could be used as leverage for educational strategies and for developing quality of life. Finally, we will develop some of the possibilities to use these “positive” aspects of autism even when there are no apparent exceptional talents.

    Paul Trehin

  2. Neoteny provides opportunity for organization of further complexity. All creative processes are fallible and not all adaptations are successful. My story is from the time when maternal rejection was the designated cause of autism, and psychotherapy for mother was the treatment.
    Berthajane Vandegrift