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

Thursday, February 17, 2011

Flashbangs and Flashbulb Memories

M84 Flashbang Grenade

I woke up this morning, at 5:15 a.m. to a loud sound that I was sure was a gun shot. I could feel vibration from the noise in my chest and I could tell that it was happening just outside my window. Without stirring, I waited and listened for something else to happen. I heard violent yelling, then at least three more shots followed, each accompanied by a bright flash of light that filled my room. I heard a person scream and then the words: “break it open, just break it open.” I could tell that the sounds were clearly coming from my next door neighbor’s backyard but then I heard people walking right next to my bedroom window – on my side of the fence. Lying still in bed, I felt like a person with post traumatic stress disorder who brings the battlefield home win their nightmares, except what woke me up was not a dream. Harshly disquieted, I grabbed a bat and went looking for a cordless phone to call 911. After a half-hour of suspecting a violent crime I finally got a hold of the local watch commander who told me that police had served a warrant next door and used flashbangs to gain entry. Flashbangs, also known as stun grenades, are used as incapacitants by law enforcement and the military to subdue and disorient. The grenades detonate with a flash of light that maximally activates all light sensitive cells in the eye, making vision impossible for about five seconds while also producing a blast of sound that disturbs fluid in the inner ear producing mental disorientation.

Once I was apprised of the fact that the noises I heard were law enforcement and not criminal I felt much better. I knew I was no longer in danger. My cat Niko on the other hand, couldn’t understand this and he was engaged in all kinds of nervous behavior that I have never seen from him. I tried my best to calm him but was disappointed that I couldn’t communicate to him that we were safe now. I quickly grabbed my things and left for the bus in an effort to make the 8:00 a.m. statistics discussion section that I teach. On the way out, I saw a swat truck and about 15 camouflaged, masked, heavily-armed men. These images were poignant but I tried to move on mentally with my day. I also tried to become aware of my memories of the event and aware of my responses to it.
Memories of surprising or traumatic events are thought to be much more accessible and are called flashbulb memories. Flashbulb memories are exceptionally vivid “snapshots” of a surprising or consequential event. Highly resistant to forgetting, these autobiographical memories are distinctive, contextually inflexible and thought to represent an adaptive, biological response aimed at preserving information about injurious or otherwise noteworthy circumstances. Studies have shown that, unlike most contextual memories that necessitate the involvement of higher-order association areas (such as the PFC and mediotemporal lobe), flashbulb memories can be brought quickly to consciousness without sustained thought. Thus it seems that our brains are equipped to rapidly reconstitute imagery about fearful or emotionally arousing situations. Normally, when higher-order areas are involved, we need a large number of coactivated representations to drive specific memorial imagery. Flashbulb memories on the other hand, can be brought back in full force with the coactivation of just a few relevant representations.
When I got back from school, stimuli at home were evoking flashbulb memories. I looked at my bedroom window and clearly heard the words, “break it open.” I didn’t summon these words, I didn’t want to hear them. My amygdala and other subcortical brain areas activated the circuits responsible for the words after being triggered by the environment. Clearly, intrusive imagery like this is more frequent and more vivid in schizophrenia or in drug-induced episodes of psychosis. Normally, the areas that cue up this invasive imagery serve as protective devices that are innately sensitive to loud noises, fast movement and threats of danger. Here this form of memory is working against me but in the hunter-gatherer past they would have been forced me to take precautions necessary to ensure my survival.
My conscious self knew better, knew that there was no real danger. But, like my cat, other unconscious brain areas and neural circuits - that don’t speak English - didn’t know this. These unconscious brain modules, like small, scared animals, continued to be emotional simply because they do not have access to the explicit, declarative knowledge that there was no real threat.