Mark Schaller is a psychological scientist and Professor of Psychology at the University of British Columbia. He graduated from the University of North Carolina in 1984 and obtained a PhD in Psychology at Arizona State University in 1989. He's been at his current position at the University of British Columbia since 1996. Schaller's research looks into the cognitive processes that contribute to stereotypes and prejudices, as well as the implications of evolutionary fundamental human motives on social behavior, the psychology of kin recognition, and the psychological consequences of fame. The reason that he's important for our class at this very moment has to do with his research into and coining of the term "behavioral immune system."

Department of Psychology
University of British Columbia
So, to talk about the Behavioral Immune System, first we have to talk about the immune system. You know, that pesky little piece of your body that throws out fevers, sweating, swelling, et al. to deal with the stress you put your body through? Well, this system is actually very metabolically costly in its attempts to keep the body healthy. To mitigate the risk of these costs ever being incurred in the first place, human immune systems have also developed behavioral mechanisms that can prevent contact with foreign and harmful pathogens. We call this system of preventative behaviors the Behavioral immune system. Any time that you feel the need to stay away from people with known illness, you're experiencing the most obvious results of this system.
Other examples of this kind of proactive avoidant behavior can be seen in nature: Schaller lists tadpoles, mice, and chimpanzees as animals that are known to actively avoid other members of their species that are noticeably ill. The primary emotion that is associated with studies of this system is disgust, and Schaller seeks to examine how these feelings can effect social cognition and interaction within a given social ecology.
So, the Behavioral Immune system can be subdivided into two sorts of behaviors- detection and response. Detection primarily depends on smell and sight to find possible risks of infection around you. This includes both objects and behaviors of those around you who may be a vector of disease. The objects that subjects experience revulsion towards seem obvious-- fecal matter, vomit, etc. When it comes to how you react to those around you, however, that's where the research gets interesting. Test groups not only responded with avoidant behavior to those who were obviously sick or clearly unhygienic, but also to those who seemed visibly different from the cultural norm. The reasoning seems to be that those who are from outside of the local culture pose a threat not only because they may carry unusual pathogens, but also because they haven't been taught the local methods of hygiene. The findings don't stop there, however; there is also revulsion associated with those who are a part of the culture but differ from the "healthy" norm: the obese, the very old, the disabled. This can all be explained by the vast array of symptoms that may be signs of disease; the system over regulates because a false positive is less likely to cause harm than a false negative assumption of disease.

Interestingly enough, test groups didn't always experience these feelings of xenophobia or revulsion. Subjects who were more cognizant of the risks of disease were more likely to want to avoid outsiders and less likely to even be friendly within their own social groups. In one experiment, groups who were exposed to a video warning about the dangers of disease and foreign pathogens were much less likely to want to recruit workers from less well known or "unsafe" countries than those who watched a video about workplace accidents. In the real world, this translates into stronger feelings of xenophobia and fewer allowances for those who are "free thinkers" or otherwise non-normative in cultures which have historically higher rates of pathogen activity and greater diversity of pathogens, such as in equatorial regions.

This sort of predisposal towards those that the behavoiral system interprets as safe can also be seen in mate selection. Part of Schaller's findings showed predispositions towards less sexually promiscuous and more attractive partners that followed the same sort of increase in areas where pathogenic activity is high. This stems both from the increase in possible vectors of infection when partners are sexually active with multiple persons as well as the perceived genetic purity of those with symmetric faces.
Schaller concludes the article with a look into the portions of the system that are as yet not well understood. The Behavioral immune system does not exist in a vacuum, and many of the systems and behavioral cues that the system encourages also serve to help other, older systems. An easy target is the fact that the eyes and olfactory system obviously didn't evolve purely to spot pathogens. However, even disgust and revulsion, the primary forces of the system, were most likely coopted from the need to vomit and expel harmful substances once ingested. Additionally, though xenophobia, regulatory behavior within a social circle, and distrust of non-normative behavior are all tools of the system, there are other behaviors thought to play a role. People like doctors, soldiers, and youth and aged caretakers are all constantly participating in behaviors that increase the risk of pathogen infection, yet they enjoy positions of respect in most cultures. The sorts of assumptions of personal risk in exchange for lowered risk for the larger culture are still not very well explained by the Behavioral Immune System model.
I found this an interesting read because I happen to be a person with a particularly overactive behavioral immune response system. My friends and family call me a hypochondriac. After reading this article, I understand why a little better. When I was a kid, I had a type of chronic strep throat that caused me to come down with a severe case of strep throat once a month. Even when I felt fine, my body was still fighting off this horrible infection. I used to play hooky from school, complaining that my throat hurt even though I was perfectly fine- just trying to skip a test or something. My mom would try and “bust” me by taking me to the doctor and having me swab tested for strep throat. Without fail, every time, the test came back positive, although I would have no symptoms or discomfort whatsoever. As a kid, I obviously milked this odd occurrence more than once. Unfortunately, I eventually got so sick that my spleen almost burst and ended having to have my tonsils removed and adenoids burned. Since then, I haven’t had a case of strep throat but I think the mentality that I am always sick has stuck with me. I absolutely refuse to share drinks with others and am a little OCD about having physical contact with strangers/acquaintances in general. Ironically, my best friend and current roommate is the exact opposite of me, which I did not fully realize until we moved in together. What is odd is that both of her parents are doctors…I always figured that doctors, being most aware of all of the pathogens and such, would also be the most precautious but through my personal experience with this family, I’ve found this not to be totally true. Immunity is built up through exposure to such pathogens so the ones that are consistently being exposed to them (like doctors) are of course building up their immunity. Therefore their behavioral immune response system does not factor in certain risky situations that others might find disgusting. I think the fact that doctors can become so “used” to repulsive things like corpses and open wounds is a strong support for the behavioral immune response system. One thing I found very interesting about this article was the correlation between social gregariousness and the perception of vulnerability to illness. Relating back to my personal life, my roommate (the extremely messy and unhygienic one) has never really come down with more than a cold. This is positively correlated with the data found in the study mentioned in the article. Although the behavioral immune response system cannot encompass the entire scope of personal risk in exchange for lowered risk for the larger culture, it definitely has a valid basis and was very interesting to read about.
I found our discussion in class on Thursday, based on this article and post, very interesting. I've always thought important to delve deeper into the reasons why we think/function/interact in certain ways, and this is reason, a Behavioral Immune System that "developed behavioral mechanisms that can prevent contact with foreign and harmful pathogens" is not one I've really considered before. And seeing the huge list we put up on the white board, it's obviously a highly developed trait of our primal consciousness.
However, I do think it is more important for us, in a developed country, to recognize it for what it is: primal. It is interesting to consider and identify, but I don't think we should rationalize acting upon this behavioral mechanism. Many of the things that made it on our list include some of the ignorant prejudices of society that we ought to be advocating against: racism, ableism, ageism, sexism, xenophobia, homophobia, et cetera. In a country with our level of development, education, and medicine, such -isms and phobias are ignorant and, while some are based in legitimate biological concerns, unfounded in practice.
If anything, this understanding of 'disgust' should actually lend itself to being more informed and tolerant.
"Why are we, as human beings, often racist/xenophobic/ableist/homophobic?"
"Because other races/foreigners/homosexuals might carry disease," our Behavioral Immune System cautions.
"You have a point, well-meaning Behavioral Immune System, however, we know that's not really a significant concern. With today's information, modern medicine and vaccines, that African American/Asian/handicapped/gay man most likely will not make us sick. We can go be their friend now."
exactly!
I loved learning about this because it gives some interesting perspectives on our behavior and evolution. It reminded me of a friend who's psychology professor asked everyone in her class to spit into a Dixie cup (everyone had his or her own, it wasn't just one giant Dixie cup of spit). They did, awkwardly, and the teacher then told them to put their spit back into their mouths. No one would do it, and their disgust was visible. We are conditioned to believe that things that come out of our bodies are out for a reason, and should not go back in. Now the spit most likely wouldn't have harmed anyone, because it was from their own bodies, but the disgust shows how we instinctively feel about potential pathogens regardless of the source or rationality.
This brings me to another interesting note. As I was reading this post I wondered how the theory would explain why some people blatantly ignore their behavioral immune response. For example, your significant other comes down with a cold but you still get close to them and kiss. Maybe people with a strong behavioral immune system would never consider doing that, but many people will knowingly put themselves in the line of fire if the sick person is someone they are close to. So, kin selection plays a role in this theory it seems. Are people less disgusted by their families, or close friends/significant others, even when they are clearly a threat to the immune system? I would say so to a degree, but we must also consider the fact that people that close to you have probably been exposed to the same pathogens, and may have a similar immune system. It reminds me of when I would get sick as a kid and warn my mom not to come near me. She would say, "I made you, I'm not afraid of your germs." Whether this was evolution or foolishness I'm not sure, but we both survived.
I like that activity!
So the Behavioral Immune System tries to explain why certain people within cultures stay away from others? Interesting. For evolution purposes it makes since that we would instinctively avoid the sick and the old. But I never really thought about it in a biological since, such as the Behavioral Immune System. The results of the study with the two groups was intriguing. Especially when those that had watched the video about diseases were not only less likely to recruit workers from equatorial regions, but that they were less likely to even talk to others within their own group. It reinforces the idea that being sterile correlates with being cold.
Translating this to real life means these people are more likely to be xenophobic. I wonder if its not just knowledge of diseases but you also have to take into account personality. As mentioned at the end of the blog there are people who do interact with the sick and dying in our society that don’t have a negative connotation, i.e. doctors. Obviously doctors have been educated in diseases yet they don’t shy away from those that are sick. I’m assuming because they have picked that career and are interested in helping people they aren’t afraid of illnesses. While those that participated in this study were not as willing due to their personality. Not saying that they are rude, but like we discussed in class are generally more aware. They might take into account that in order to perform well in the office they need to hire healthy people. While doctors and people who have regular close contact with the sickly aren’t as business minded.
I also never really thought about the role that the Behavioral Immune System had in finding a mate. But it makes since, I didn’t realize that there was a biological reason for why we are attracted to pretty people.
I spent the entire article thinking of my sister. She is the biggest germaphobe I have ever met. I’ve always thought of it as some bizarre habit that had no reasonable application in daily life. I’m glad to see that was wrong. I guess I understand not wanting to eat or drink after someone but she goes to some pretty absurd extremes. This might not be that uncommon for some people but my favorite freakout of hers has to be cockroaches. One time a roach ran into her room and wasn’t found so she slept the next couple days on the couch, but that ended just as quick we she saw the same roach scurry across the couch. It probably makes me a terrible brother but I laughed about that for days (and I still torment her from time to time). But I know I should be understanding, some bugs are fairly disgusting and roaches especially can be carriers of some nasty pathogens and look downright terrifying. I can’t give her too much flack though, my biggest repulsion is pretty out there. Pickles. I can’t even watch someone eat one across a room without my gag reflex kicking in, which is strange since as far as I know pickles have never hurt anyone- well unless you include me and my taste buds. I wish I was aware of the event that made my behavioral immune system develop my pickle aversion. Did I get sick after eating one when I was 3? Did I almost choke on one as an infant? If only I knew.
But my ramblings don’t come close to the heart of the article. I think it’s amazing that we have a natural, biological aversion to other cultures and that this aversion was actually an important part in our evolution. Before globalization pathogens were well contained and specific groups had immunities built up for the diseases found in their area, and even today there’s areas of the world which we can’t travel to without loading up on vaccines to prevent the contraction of diseases we aren’t generally exposed to. The Native Americans dying from diseases brought by European settlers is a good example of why our Behavioral Immune System would want us to avoid contact with outsiders. It also seems interesting that our Behavioral Immune System plays a major role in partner selection. It seems obvious that we would avoid sick people when choosing mates, and knowing a person has a high level of sexual activity would be unappealing to many people so we can avoid contamination. But the desire to find a similar mate to keep genetic purity seems like an odd trait to me. Diversification would increase immune health, and when breeding lines are too close genetic illnesses like hemophilia become more common. All in all the Behavioral Immune System is an incredible thing and I never would have assumed it would have such a huge evolutionary role.
Oh my gosh guys, I think this theory encompasses my whole life. I can definitely relate to its grounds as I have many weird occurrences falling into these categories.
First off, I, like Hannah Gene, spent a lot of my childhood home sick from school. I would feel sick all of the time, and even tried to stay home when I felt well. It even got to the point where my doctor and whole extended family had to develop a plan to get me to stop faking sick, even though the majority of the time I wasn’t faking. I would feel nauseous, dizzy, weak, and light headed all of the time, but my doctor could never find a reason for me to be feeling this way. This went on all the way up until I was a teenager, and I was really put off by the fact that no one ever believed me when I was telling the truth.
Well turns out now I have been diagnosed with a heart condition that makes my blood pressure really low, explaining all of the symptoms I felt as a kid. But I wasn’t diagnosed until last summer when I passed out at my internship. Talk about embarrassing; especially since I was on camera reporting at the time (thank God it wasn’t live!!) I went to a cardiologist and found out that all of this was caused by my chronic low blood pressure and that it causes me to slip in and out of consciousness with no warning.
Also, this theory relates to my life largely as I have an irrational fear of puke. Yes, I am terrified of puke. This goes back to my childhood and according to this theory, I think the reason resides in my undiscovered heart condition. I would love to find additional research on this topic to find a way to curb my fear and better understand it. It causes a lot of problems, especially since I’ve been in college.
As a follow up comment I have been thinking a lot of how much past experiences affect us and control our lives even to this day. I mean look at me and puke, I still can’t do it no matter how sick I am. I am amazed to see how subconscious thoughts turn into fears and strange actions. I would love to expand on this theory and further learn the implications of it. I see the effects of it in my daily life, even reaching out to my personal hygiene. I think this theory explains why I am so OCD about cleanliness and avoiding germs. It’s amazing how much this theory was able to educate me on myself.
I loved this article!
The other day in Anthropology 450- Evolution for Everyone, we were discussing a girl’s project in which she had studied bubble wrap popping and the behavioral immune system. I don’t think she reached any real conclusion, but it was interesting all the same. I am a very big skin picker, hair plucker, and zit popper so this sort of information is very relevant to me. However, I feel that I have a low-ish sense of revulsion towards these things. I think they’re neat! So, I am clearly part of the group that is not well explained by this model.
I do think that perhaps the reason some individuals do not fit the standard model maybe has less to do with a group selection hypothesis and more with your standard natural selection on the individual. I started liking to drain blisters on myself, not other people. There are plenty of people out there who are grossed out by their own issues. I am not one of those people. I can remove dirt from a pore and sometimes smear blood around on a cut just to make it look worse. I’m weird. But my ability to deal with things and perhaps potentially decrease my own pathogens might lead me to assisting others (Justin gets great blackheads!), just because I like to do it. So it’s sort of a byproduct of my own adaptation.
I really agree with what Hannah Gene has to say about the behavioral immune system not being an “excuse” for xenophobia. Many people site the way they were raised as an excuse for their ignorance or intolerance. When you are an adult, however, that is no longer an excuse. I’m not sure if this is entirely relevant, but a couple of months ago I read an article in Slate about the racial empathy gap. Apparently a study done in Italy found that both white and black people felt that black people felt less pain than white people in the same scenario. For instance, when shown a picture of white skin being pierced by a needle, they said that person would be in higher pain compared with the answers regarding dark skin being pierced by a needle. Just reading that article made me feel like a horrible person. But this lack of empathy clearly affects both our healthcare and criminal justice systems. I would really like to know if this is somehow a part of our behavioral immune system and what might the evolutionary reasoning be behind this.
The behavioral immune system is fascinating. While my boyfriend might not feel as bonded to me as chimp would its grooming partner, I think he totally understands why I pick at him. I mean, I’m just decreasing his pathogen load after all.
I’m including links to the Slate article and a link to /r/popping. You know, just cause.
http://www.slate.com/articles/health_and_science/science/2013/06/racial_empathy_gap_people_don_t_perceive_pain_in_other_races.2.html
http://www.reddit.com/r/popping
I thought this article and our activity in class were so fun because these preventative behaviors are the product of millions of years of evolution. However, I thought the most interesting part was the fact that the cultural response to some stimuli is very different. In many developing countries where they don't have indoor plumbing and other like amenities, people simply deal with things that we in the western world think are disgusting. I was browsing the internet the other day and saw that India has a mascot of sorts called "Mr. Poo", who is part of the country's campaign for public sanitation (if you don't believe me just look here http://www.telegraph.co.uk/news/worldnews/asia/india/10780448/Meet-Mr-Poo-the-star-of-Indias-public-sanitation-campaign.html). If somebody took a dump on the sidewalk in the united states, the police would definitely be involved. In many parts of the middle east, it is considered rude to reach for food with your left hand because it is used for certain 'ahem' bathroom duties. I remember my 8th grade science teacher talking about a trip to somewhere in the middle east where he used a bathroom that had a jar of water to wash off your hand after wiping. I suppose this is a product of their lack of things like toilet paper, because they still are disgusted by the behavior.
In our class activity, it was really interesting to see that some people were particularly disgusted by things like not washing their hands after the bathroom, and some people were not bothered by it at all. I suppose that is because some things (like washing hands) are taught, while avoiding things like vomit are instinctual. Back in early human history, I'm sure that people were more conscious of people vomiting than not washing their hands.
I thought that Hannah Gene pulled out a great quote from the article in her comment as to why we often fear "other races/foreigners/homosexuals might carry disease", not because we are necessarily intolerant people, but because it is an instinctual response. This makes me think of an episode the show "Bizarre foods with Andrew Zimmern" where he is in an African market full of rotten food and he is very hesitant to try any; while these people have been eating spoiled food for their entire lives, he is not accustomed to that sort of fare. It is not hard to wonder why we naturally avoid foreign things when we have not developed a tolerance to them. I have no doubt that humans will always have a natural response to feces and vomit, but I believe that we will continue to find new phobias like unwashed hands as we continue to advance.
I only commented on this 20 hours ago BUT HERE WE GO AGAIN. I still love this article! Who would have guessed? I still love popping zits! So not much has changed in 20 hours!
Another thing I was thinking about is why doctors enjoy a higher status. I had an idea of why they might enjoy dealing with other people’s pathogens, but why would they have a high status because of it? Well that’s actually pretty simple isn’t it? They help people do things others might be disgusted by. I find that extremely useful and probably a great person to have around.
Hand washing, as Matt mentioned, is a behavior that people have recently began to use. Some people still do not wash their hands after every visit to restroom, even when they poop! Gross! So while my threshold for grossness seems pretty high, apparently I am not even immune to being grossed out by unhygienic behaviors.
Also, I was talking to Justin earlier about this and he wondered why humans kiss. It’s not specifically for reproduction and surely it would add to your pathogens, right? Maybe you wouldn’t kiss anyone who is clearly loaded with diseases, but others might.
The behavioral immune system is totally fascinating, but I would really like to know more about why some of us participate in behaviors which are probably completely counterproductive when it comes to staving off pathogens.
The activity in class, where we listed different types of repulsive things in our society was thought provoking. To me it seemed like the Behavioral Immune System was justifying racist ideas and homophobic ideas. Not only that but some of the things that grossed people out would be considered normal in other societies. It seems that this system could easily excuse xenophobic behaviors among people. I understand why the immune system would develop to be wearing of this sick and unknown people due to potentially harmful pathogens. But when teaching about the Behavioral Immune System I think they should stress its evolutionary purposes and not as an excuse for to discriminate against others. On another note I thought the experiment with the smelly, sweaty shirts interesting. It was gross, but interesting. I knew that people are drawn to those that have naturally appeasing smells. But I never knew why, nor that it would be connected to the body’s immune system. The way the body subconsciously works is such a mystery for me. I definitely believe that delving further into the Behavioral Immune System and its impact on the way we think about others.
Ah, disgust. This topic is so strangely interesting. What stuck out to me this time around was the concept of detection and response, and the tools it gives us to combat the negative effects of the Behavioral Immune System. Several people have commented saying that this system cannot be an excuse for intolerance of others (xenophobia, etc), and I think by increasing the individual’s consciousness of the Behavioral Immune System’s process, he or she could decrease the frequency of negative responses. Once we become aware of the fact that our brains are constantly attempting to detect a pathogenic threat, we can stop it before it reaches the “response” phase. Like Hannah Gene said, we can ask ourselves why we are subconsciously inclined to react a certain way to someone or something. If it is not constructive, simply acknowledge the threat detection and override it. I’m not saying to go lick someone else’s vomit, I’m just saying don’t be afraid of foreigners. Often enough, too, our detection systems are flawed. Your Behavioral Immune System may think it has detected something threatening, or seen something disgusting, but it is merely out of a conditioning that is not necessarily accurate. Think overweight people who can run marathons, grandmas who will lap you for days on the indoor track at the YMCA, or people with excessive body hair that have excellent hygiene. This all just goes to show that our primitive responses, while doing their best to protect us, don’t always serve the greater purpose of acceptance.
The more I read about the Behavioral Immune System the more I realize a lot of it is developed by society’s opinion on actions. Kids often do things most people consider gross, and while rereading Hannah Gene’s article about kids a few points kinda grossed me out. When she talked about being forced to sit at the kid’s table with her cousin Mikey, who picks his nose, I immediately thought of the Behavioral Immune System. It made me realize a lot of this system is learned from our environment and before we’ve been fully immersed into society we’re unaware so many of our actions gross others out. I mean I’ve seen plenty of kids pick stuff off the ground and stick it straight into their mouth, yet most adults would be repulsed by this behavior. At the same time, the same child is scared to sit next to a girl cause cooties. Good thing they have their priorities straight.
In addition to child development, I noticed strong implications of the Behavioral Immune System in Matt’s blog about religion. The Jews have developed a sort of xenophobia which has allowed their culture to survive throughout time even though they faced so much turmoil. They are one of the only major religions to attempt to remain culturally pure in the way that they have, rarely marrying outside their culture and even living in tight-knit communities. Both of these are qualities that Schaller describes in groups that have strong Behavioral Immune reactions.
I thought it was funny that tadpoles, mice, and chimpanzees are among some of the animals that avoid other members of the group that appear to be ill because fish totally are not. I was just at the pet store the other day to get a fish and left immediately in disgust, I guess from my behavioral immune system, because the fish tanks had become a fish cemetery in which the not-so-grieving remaining fish were chowing down on their not-so-lucky comrades. It was revolting. But anyways, I think the behavioral immune system is an essential, primitive function that helps keep the human species alive and kicking. I'm glad that I am grossed out to share my drinks with others. My friend has gotten strep throat twice by doing that. The behavioral immune system reminds me of our flight or fight response. You detect a threat and, if you're like me, the flight response kicks into gear, helping you to avoid being harmed by that potentially dangerous situation. Our behavioral immune system works in the same way and, until now, I had no idea it even existed. It's just so cool to me how our bodies are set up to protect us in ways that we don't even realize are taking place at the time. Being a hypochondriac, a I stated before, I can relate to the experiment that was mentioned in this article. The more information I am given about germs, disease and things that can go wrong, the more cautious I am to avoid being exposed to them.
When I was in Psychology 101, we studied the concept of revulsion to human expulsions. All humans are revolted to almost all sorts of human excretion, including your own, but we do not find these things repulsing when they are still inside us (are you grossed out when you hear your stomach turn?). This is as Tyler said because these things are all causes of disease. I think this is what this idea refers more to and the ideas on xenophobia and racism are more maybe a slight combination of this and societal norms. A good example that was mentioned in the comments was kissing. Obviously we are not grossed out by our significant others, but kissing in itself is a pretty gross activity if you think about it (imagine two butt ugly people kissing). It’s usually not a pleasant thing to watch and doesn't really serve a purpose, right? I think this theory explains it very well: the fact that we aren't grossed out and want to kiss someone is an ultimate sign of trust (biting the bullet as was mentioned before). This exchange of fluids (even more gross in this light) is a precursor to a more meaningful exchange: sex. We are more likely to trust someone to not have an STD or have terrible genes if we are willing to kiss them first, and this seems like common sense, but the behavioral immune system contradicts it. So there are evolutionary exceptions to the rule I believe, and we should keep that in mind in discussions of race and xenophobia. These problems in my opinion are a larger part of society and the issue is a very personal one for me. I personally have always had a hard time in school growing up in the south making new friends (I moved here when I was 5), and the further along I go, the less it seems to affect me. This is largely due to my own personal reticence to reach out because of fear of rejection, not because I’m scared they’ll give me germs. I get that this timidity comes from the behavioral immune theory, but then why am I now going to a predominantly white school when I was offered the same scholarship to a school whose population was 50% Indian? I could be an outlier, but what sets me apart is that I have grown up here whereas those who opt for the latter grew up surrounded by Indians suggesting the status quo is what we seek.
Watching attractive people kiss is not as gross, is it? Interesting study idea...
Kind of hard to give fresh input on something I just commented on a few days ago. Reading it again, I started wondering if the behavioral immune system is something only for humans. My dog has no problem eating poop or pretty much anything gross; but why is that? Is it because her stomach and immune system can handle things better than mine? Why does something so disgusting to me seem to appeal to her so much? Going along that line, when I went to the Chattanooga zoo (it's a very pathetic zoo I wouldn't recommend) a few years ago, I literally saw a fully grown chimp take a shit in his hand, and proceed to eat it. If the behavioral immune system is some function related to higher intelligence, then why did one of our closest ancestors eat his own poop?Thinking about all of this makes me wonder if we have a comparatively weak immune system to other mammals.
You have no idea how often this question comes up, so I've researched it a bit. Simply, dogs have different intestinal flora than we do & different immune systems. They actually evolved, mostly likely, because the less timid wolves were enticed by our garbage to come close. Dogs are attracted to anything with a strong smell. They have a different mix of neural receptors for taste/smell than we do &, yes, different immunological agents. That said, my husky gets diarrhea every time he eats anything that has a hint of gluten in it, while my chihuahuas can eat anything & everything & never suffer. So there's variation there too.
Re the chimp, we really can't make fair comparisons of anything based on zoo primates. If you spent your life in prison, you'd likely take on some habits alien to the rest of the general population too. Caged primates have higher tendencies toward alcoholism, smoking, & all kinds of other things we don't normally associate them with, but which we do associate with stress in humans. Eating one's own poo, well, what is that video? Two girls & a cup?
This article was fascinating in the way the human mind responses to potential harm. It reminds me of Darwin and the survival of the fittest, because creatures that work to avoid potential risks in health or safety, appear to be the organisms that will sirvive and prosper. However the one element of the article that really made me think was the idea of the prejudice that humans place on other humans. The brain is so complex in the way that it avoids threats, but it makes me curious as to who got it in their heads that entire cultures of people could be considered harmful. It is mind boggling to me that one day someone decided to stay away from an entire group of people, and that this idea of complete isolation from a group of people ended up catching on. How many wars would have been prevented if it weren't for this mentality? How many slaves could have been saved? When I was about twelve of thirteen, I remember having a conversation about race with my dad in the car, and I remember him having to tell me that racism was still around today. Because I have spent my entire life growing up and living in Los Angeles, I grew up completely accepting people of different races and cultures, and I never even thought anything of it. I remember my dad having to tell me multiple times that racism had not died away, because I didn't believe him. Moving to the south has been quite a culture shock in this way. In the fall of my freshman year I joined a sorority, and (as everyone knows) there was quite a bit of controversy within the last year about the issues of race and racial equality. I remember sitting in the living room of my sorority house and having to listen to a discussion about what was going to happen with the inter gratin of sororities. Do you know how much I hate it that I heard the word "integration" be tossed around in common conversation? Before these issues came to the surface, the only other time I had ever heard the term was during the movie musical Hairspray, which takes place in the 60's in Baltimore. The 60's! The idea of racism is absurd to me, and it makes me wonder how we got to this point as far as the behavioral immune system is concerned, and why we have not progressed further at this point in time.
When I was growing up, I was witness to my little sister's constant struggle with her immune system that became a major source of stress for our family. With the use of hindsight, we have been able to see that my sister was a pretty high-anxiety child, which seemingly weakened her immune system. Her constant bouts with strep throat and recurring stomach pains were emotionally taxing on my mother who not only had to deal with a sick child, but a child that was also developing an overly sensitive behavioral immune system. Attempts to take my sister to the doctor so she could get better were a process, as she became convinced that going to a place with that many sick people was only going to make her even more sick. After many years of this behavior, she seemed to kind of "grow out of it" but signs of her overactive behavioral immune system remain intact. She still eats very bland foods because more exotic varieties will "make her sick," she still can't stand the thought of a doctors office, and the mere mention of her worst fear (throwing up) is enough to ruin her day.
While I have often been critical of some of her more ridiculous fears, seeing this microcosm of the behavioral immune system makes me more understanding of her responses to sickness. Contextualizing her behaviors as part of an evolutionary response to learned stimuli has opened my eyes to why our bodies respond to stress.
Follow-Up Response:
Since being introduced to the concept of the Behavioral Immune System, I've become more aware of its influences and been able to recognize this kind of instinctual xenophobia in social settings. It has also provided me with a better perspective to understand some of the more illogical reactions caused by the presence of this behavioral immune system.
The article points out the tendency of individuals to be instinctively experience revulsion at people who differentiate from the health norm. While visible discomfort is observable in many people around elderly, handicapped, and (somewhat understandably) sick people. But this discomfort seems to be the most pronounced in people interacting with someone who is mentally handicapped. While this discomfort is completely irrational, it is easily explained by the presence of a primal fear of people who are different or seemingly unhealthy. The same principle can be used to explain other such inexplicable social trends, such as homophobia, or the subconscious and unsolicited racial segregation that seems to inevitably happen within large groups of people. When it is understood that these trends are simply the result of irrational subconscious discomfort caused by outdated primal defense mechanisms, they can be better combatted within our society. Understanding intolerance in this way is the first step to changing it.