Could Hiccups Represent An Evolutionary Reflexive Response to Choking?

I have long wondered about the evolutionary or adaptive value of hiccups. As a child I used to hiccup a lot and they seemed strange and inexplicable. Some recent experiences helped me to see that hiccups may play a role in swallowing. More precisely they may serve to help mammals recover from choking by clearing the esophagus. On several occasions I have had a mouthful of food block my esophageal airway. When this happens with a particularly large mouthful, it can partially occlude the tracheal airway making it hard to breathe. Several times now I have been saved by a hiccup. The hiccup literally squeezed the food down my esophagus and into my stomach.

A hiccup is like a cough in reverse. During a cough the diaphragm expels air from the lungs as the glottis opens. During a hiccup the diaphragm pulls air into the lungs while the glottis is closed and I firmly believe that this can pull food down the esophagus. Most people experience several hiccups in a row usually not coinciding with a meal or with choking. Perhaps these normal hiccups are the body practicing this important reflex. I would be very interested to know how many other people have experienced a hiccup while choking and had their airway cleared because of it.

It happened to me again today. I was eating way too much food, way too fast and I had an uncomfortable feeling in my throat. It is a strong sensation that usually induces a bit of panic. This often happens when I eat something dry without drinking anything. Have you ever eaten a hard-boiled egg first thing in the morning? When this happens I always hiccup, but only a couple of times. The hiccuping tends to push the food down my esophagus, relieving me of the choking feeling. Could most cases of the hiccups represent misfirings of this important, hair-trigger reflex meant to keep our airway clear?

Important reflexes come out sometimes even when they are not needed. At times we salivate despite the fact that we are not about to eat. We often stress out, releasing adrenaline and cortisol despite the fact that we are not about to engage in strenuous physical activity. For a long time now I have concluded that random bouts of hiccuping are triggered accidentally but represent a  means to constrict the middle respiratory tract forcing large boluses of food down so that they do not obstruct the trachea. I can think of many ways to test this hypothesis experimentally, anyone want to help?




Here are some of my favorite books that explain how common human traits are actually adaptive biological responses:

Psychopathy is a Selfish Behavioral Strategy that may be Programmed by Ecological Adversity

Psychopathy, sometimes known as antisocial personality disorder, is characterized by a lack of empathy and severely amoral conduct. Because people with psychopathy have so much trouble empathizing they are much less afraid to cross social boundaries, insult or hurt others. Because about 1% of the population are psychopaths evolutionary psychologists have come to believe that psychopathy may represent a viable ecological strategy that helps an individual to selfishly gain resources by taking advantage of others. Our hunting and gathering ancestors have relied on cooperation for millions of years and this is why most people are not psychopathic. Perhaps though, in small numbers, genes that influenced individuals to be less helpful and more selfish benefitted those that bore them explaining why psychopathy is heritable and why genes for psychopathy exist in the human genome. It is too bad that these genes can’t tell if the environment is a healthy, friendly one that is conducive to team playing or if it is a bad one which would reward those that defect from the team. Maybe the genes can tell...

A good deal of very interesting research points to the fact that environmental cues can switch on genes that would normally stay dormant, resulting in changes to the body and brain. For instance, water bugs whose mothers are stressed out by the scent of their natural predators make babies that have totally different protective armor. A huge number of similar “predictive adaptive responses” to environmental adversity have been documented in animals and even humans – many arising from prenatal stress. Studies of the Dutch Hunger Winter of 1944-1945 have shown that individuals born just after this famine are more likely to have lower metabolisms. This is thought to represent a predictive response to low food availability. Interestingly, these studies also show that these famine-born individuals are more likely to be psychopathic.

It is difficult to say exactly what this means, but it suggests to me that humans may be programmed by early environmental stress (and perhaps postnatal adversity too) to be selfish, manipulative, guiltless and antisocial. It would make sense for natural selection to program us to be more deceitful and cunning in a hostile environment that is marked by scarcity and thus high levels of competition. Such a change would force the person or animal to look out for number 1 – to look out for its genes. Peruse the following clinical rating scale from the PCL-R and ask yourself: “what kind of environment would these traits go along well with?”

Psychopathic Traits:

Factor 1: Aggressive narcissism

1. Glibness/superficial charm
2. Grandiose sense of self-worth
3. Pathological lying
4. Cunning/manipulative
5. Lack of remorse or guilt
6. Emotionally shallow
7. Callous/lack of empathy
8. Failure to accept responsibility for own actions

Factor 2: Socially deviant lifestyle

1. Need for stimulation/proneness to boredom
2. Parasitic lifestyle
3. Poor behavioral control
4. Promiscuous sexual behavior
5. Lack of realistic, long-term goals
6. Impulsiveness
7. Irresponsibility
8. Juvenile delinquency
9. Early behavioral problems
10. Revocation of conditional release

Here are some of my favorite books that explain how common human traits are actually adaptive biological responses:

Mapping the Spatial Relationships Between Cortical Inputs

The cerebral cortex is a big sheet of neurons about 2 millimeters thick with a surface area of about four 8.5 x 11 pages of paper. Under this thin sheet of gray matter (neuron bodies) lies all of the white matter that creates the connections between neurons. The physical characteristics of neurons differ a little throughout the sheet but the main differences - that determine what the neurons process – are found in the inputs. Inputs from the sense organs and other brain areas feed into the cortex in a distributed way. I believe, that if you want to know, in general, what a small patch of cortex does, the best way to do this is to look at the inputs that feed into it. Particular areas of cortex are programmed by not only the nearest input, but other nearby inputs. These inputs probably work together, triangulate or overlap like circles in a Venn diagram, to determine the relevant functional properties of nearby cortical tissue.

 Input from the retina feeds right into cortex in the back of the brain and this is why occipital cortical areas there process visual stimuli. Up near the top of the head, in the somatosensory strip, are inputs from sensors on the skin. This strip of cortex is thus responsible for processing touch information from all over the body. But what about half-way in between these two areas? What is processed in the space between visual and tactile? The parietal cortex sits in between these two areas and its main function seems to be almost a split between visual and somatosensory processing. The parietal cortex is responsible for our mental representations of personal space, the areas right around our body. Could it be that the function of parietal cortex is determined by a combination of its nearest inputs? I think so. As another example, consider the temporal lobe which receives inputs directly from the cochlea of the ear. As you might guess much of the temporal lobe is involved in identifying the source of heard sounds. Guess what the area intermediate between visual and auditory cortex is involved in? It is involved in the recognition of conceptual objects, normally things that both have visual forms and make audible sounds.

 In more complex areas you have several inputs, very close to each other, coming from sensory organs, other cortical areas and also neuromodulatory systems that release transmitters like dopamine, serotonin and adrenaline. This gets very complicated, very quickly, but I have a strong hunch that the unique connectional trigonometry of patches of cortex determines what kinds of things their neurons are exposed to and how they "perceive" the world. Many diagrams that I have seen in neuroscience display the inputs and outputs associated with different areas but contain no information about the spatial orientation of these inputs relative to each other. For many reasons, I think that the spatial configuration of cortical inputs is very important and will be instrumental in determining function in different cortical areas - especially those with multiple, multimodal, overlapping inputs such as the prefrontal cortex.  

The “Solitary Forager” Hypothesis of Autism: www.solitaryforager.com

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:  www.epjournal.net/filestore/EP09207238.pdf


You can also find an early and unabbreviated version here: http://www.solitaryforager.com/
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

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.