Transcript - Scientific Proof, toxoplasmosis

Class: Informatics, Computing, and the Future

Instructor: Dan Berleant

Transcriber: Brooke Yu

Date: Thursday, March 14, 2013

Professor:  Okay.  So let's see where we are.  So we saw that movie, discussed it, and today we'll go to a new topic.  We'll start out by talking about the concept of scientific proof.  Next week we have spring break.  How many people are going out of town?  Okay.  Anybody going out of state? 

And then Tuesday when we come back, the plan is that Harry Pence from another university will give us a lecture by remote and we'll do that through Skype. 

He'll talk about the future of data information.  So homework due today and then no homework will be passed out until after break.  Any questions? 

Alright so let's find out about whether scientific proofs exist. 

I'm sure you've heard of the concept of scientific proof, right? 

But really, in science, things are not proved.  Okay?  Science let's use discover things about the universe, but it doesn't actually prove anything.  You probably think that sounds like something you haven't heard before.  Has anyone heard that concept before? 

Let's see.... I'll explain what I mean.  The concept of things like science not proving things....

Male Student:  What about laws? 

Professor:  What laws? 

Male Student:  Like gravity. 

Professor:  That's an interesting point. 

Male Student:  I thought if it wasn't proven it was a theory. 

Professor:  Well, all we have are theories.  Newton was the first to discover the law of gravity.  It was a fairly simple equation.  See if this is the right formula. 

Okay.  This is the law of gravity.  It says that the gravitational force is equal to the two masses times the gravitational constant divided by the distance between the center of the masses squared. 

Like your mass times the earths mass.  If one person weighs twice as much, then the force doubles. 

Well, so you're suggesting that one can prove this. 

This will get into what I'm talking about.  This is not something you can prove is exactly true.  But how do you know that there's not some small factor that would make this formula slightly different but give a similar enough answer? 

Did I just say that too fast? 

Do you see where I'm going? 

Do you understand what I said?

Male Student:  There could always be something else. 

Professor:  Right.  When you do experiments, you don't realize that.  Einstein came up with a different formula, and his formula is more right than newton's formula.  I don't know what it is- it's more complicated.  But einstein's answer is slightly different than this answer. 

So that's a pretty good example of why a theory can't be proven.  This is now known to be wrong, but it's pretty close.  It's not bad as an approximation. 

So we can do all the experiments we want but we can't prove it's the correct formula.   That's how scientific research is often taken to proceed.  You come up with a theory then make experiments that corroborate the theory, but you don't know if it's right or just almost right. 

So let's see how this plays out in the context of the difference between context and mathematics. 

Do you know that mathematics is not a science, right?  What's the difference between mathematics and science?   Or what's a difference? 

Why don't we call math a type of science? 

Well, because science is about the world and mathematics is not about the world but about numbers and properties of numbers. 

Often times you can use mathematics to help understand the world, but the mathematics themselves is just simple manipulation.  Numbers. 

So in math, math proves new things based on existing knowledge- using known things about mathematical facts.  And they make deductions.  They can prove new things from old things.  I'll give you an example here. 

Here's an example of a mathematical proof. 

1+1 = 2, 2+2= 4, so 1+1+1+1 = 4. 

This is how I prove this [On board.]  

I didn't have to do an experiment to discover this.  I just deduced it by careful reasoning. 

So that's called deduction.  You have some starting points and you use reasoning to come to a conclusion.  That's called deduction. 

You deduce things. 

Okay, here's another example-  A very classical example.  This is very old.  All men are mortal.  Socrates is a man, therefore Socrates is mortal. 

If these two are true, then this must be true just by pure reasoning alone.  You don't have to check the phone book to see if you can look up Socrates.   This is pure reasoning.  Deduction. 

This time of deduction is called syllogism.  I don't know why, but it's an example of a logical argument. 

So deduction can prove things. 

Okay, this is actually another syllogism. 

Using deduction, we can prove things. 

Mathematics uses deduction, therefore mathematics can prove things.  If you accept this, then you have to accept that. 

What do you think?  Does this work? 

Male Student:  Did you just say absolute truth for syllogism? 

Professor:  Alright, this is an absolute truth.  If these two things hold, then that is true. 

Male Student:  Well, about that- there's a quote from ananonymous philosopher - an a world void of absolute truth, opinion prevails. 

Professor:  So that person is arguing that absolute truth must exist. 

Professor:  Okay, so maybe these are opinions.  If these opinions are true, then this is not an opinion- this must be true.  If you agree with these opinions, then you have to agree with that.  You can't hold these opinions and then not hold that opinion or you're not thinking straight. 

Male Student:  But then you could just call them facts. 

Professor:  Okay, I'm calling this a fact.  It is a fact that if you accept these than you accept that.  This whole thing is a fact.  But if this and if this, then that's a fact. 

If you accept the premises, then you must accept the conclusion if you're a rational person. 

Okay?  What do you think Rosio?  Do you agree? 

Okay, so.... but science is different from math.  It's based on induction, not deduction. 

You've all heard the term deduction, right?  I don't know mean tax deduction. 

Male Student:  Thanks for clearing that up. 

Professor:  Has anybody heard of the term induction? 

Some people have, okay.  So induction is a different reasoning process.  It's not like 1 + 1 = 2.  The process of induction works like this. 

I'm going to look at apples falling off a tree.   I notice everytime it breaks off the branch it falls to the ground and hits newton on the head or hits the ground. 

You've heard that story?  Newton was sitting under a tree and an apple hit him on the head and he discovered gravity

So you're watching the tree from afar and you see apples breaking off the branches and falling to the ground.  If an apple breaks off, it'll fall down.  You haven't proven anything, but you've made an observation- you come up with a theory that if you shake the apple tree, then an apple will fille.  

But that's not a proof.  That's just reasoning from experience.  And that's called induction. 

So you agree this is a not a proof?  Anyone want to argue that is kind of a proof or almost a proof?  Or anything? 

Can anyone think of a counter example to this where you shake the branch and the apple doesn't fall to the ground when it's loose?  Let's say you've trained the dog to catch balls. 

The apple start to fall and you hear a whoosh and the og catches the apple.  The apple never hits the ground.  It could happen.  Or a bird could catch the apple and it flies up. 

Male Student:  It doesn't say anything about the ground though.  It just says it'll fall down. 

Male Student:  I thought it could just be sitting on a branch underneath it and not fall, but it would probably still fall a little bit. 

Professor:  Let's modify this a bit.  Your first hypothesis is that the apple breaks off and falls to the ground.  You shake the tree and 100 fall to the ground.  You shake again and the next apple only lands on the branch.  So it doesn't fall to the ground, it just falls. 

Then you shake the tree 1,000 more times and most hit the ground.  Suddenly one day a bird flies by a catches the apple and flies to the top of a building.  In that case the apple doesn't fall. 

Male Student:  It just says it falls down. 

Professor:  Right, we refuted our first theory that it fell to the ground.  We refuted the fall down to the ground theory, so our new theory is that it just falls down. 

Then the bird comes along and the bird may catch it and fly away then eats it at the top of a building.  In that case the apple never did fall down at all. 

Well, then we can come up with a third theory.  We could say that if some agent doesn't catch the apple... to cover the bird case.  So that's the scientific process.  Eventually you do experiments that test the limits of the theory and you come up with ways to refute the theory.  Then you come up with another theory. 

Like the falling down to the ground doesn't work so we change it.  Then the bird comes in and we have to adjust again. 

You know, then some person will really test the theory and they'll take a branch of an apple tree and put it under water and the apple goes up instead of down.  Because apples float, right? 

Okay.  So anyway, this process of coming up with new theories and refuting them- that's the scientific method, and it's different from what they do in mathematics. 

So this is called induction where you reason from multiple examples to try to come up with multiple explanataions, but you're not proving anything. 

You know, here's another example of something more general.  If you throw something up it'll come down.  But you can think of counter examples.  You throw up helium balloon and it won't come down.  If you're in water it won't come down, it'll float.  

Maybe this is true, but you just didn't do the right experiment. 

Okay, well, science needs more than pure induction where you count up the times things happen in your observations. 

In science, we want to understand the why of things.  We don't just want to know that apples fall down or don't fall down.  So newton came up with a why. 

This was his explanation.  Science calls these reasons theories and hypotheses.  What's the difference between the two?  Theories are big and hypotheses are the small ones. 

Relativity and evolution....

Male Student:  A theory is just a well-tested hypothesis, isn't it? 

Professor:  Not really.   A well tested theory or hypothesis is just more believable.  But someone could come up with a wild-ass theory.... some crazy theory, but it might be dismissed immediately. 

People are always coming up with hypotheses that are proven to be wrong.  In doing research you're supposed to have hypotheses to test and they might turn out wrong.  They test them to see if they seem to be right or if they can prove them wrong.  You can prove something wrong, but you can't prove something right

Theories are things like relativity, and hypotheses are little things like if the ground gets water-logged my basement will get wet or [On board.] 

Okay.  Any other comments at this point? 

Alright, so.... in conclusion, math proves things and science does not.  Science does disprove things by refuting inductive conclusions.  Science could disprove the theory that the apple falls by finding a bird that will catch the apple, or finding strange environments in the universe where newton's formula is wrong and Einstein's is right. 

I think when they're trying to design satellites they have to use einstien's equations. 

So science operates by disproving theories and hypotheses.  You can't prove anything- you can get more certain, but maybe someday someone will. 

So science operates by induction and ties to explain things- not only that the apple falls, by why, and science makes prediction.  If I shake the apple tree, the apple will fall.  If I go shake a pear tree, then the pear should fall too.  That's another prediction. 

Well, the problem here is that the phrase scientific proof doesn't make much sense.  You could build up evidence for a scientific theory- even 99.9% evidence, but there's always a possibility that another experiment might prove the theory to have an exception or be not quite right, or just wrong. 

If you were going to prove something scientifically, you'd have to do all kinds of experiments, but how do you know for sure there's not some circumstance in which it might not work?  So no such thing as scientific proof

Male Student:  Well, there's inductive reasoning, right? 

Professor:  Yeah.  You'd be a fool to say einstein's equation can't be proven, so I won't believe it and I'll just ignore it.  That would be wrong because it's a pretty good bet that it'll work the next time you use it.  Just because there's no such thing as scientific proof, that doesn't mean einstein didn't come up with something that's useless or incorrect. 

If you read in the popular press, especially about socially controversial things, people say "they didn't prove It."  Well, that's an impossible barrier.  There's no such thing as scientific proof. 

I'm sure someone arguing that the earth is flat and is good at it could just shred us.  We could say the earth is round.  That's true for anything that someone cares about.  They can argue a whole bunch about it, but that doesn't mean they're right. 

Alright.  So what I'm trying to get at here is something you can use everyday in life.  When you read about scientific proof, just know you can't prove anything absolutely.  That both helps and hurts people's arguments.  But if someone demands scientific proof then they'll never be satisfied.  You can come up with overwhelming evidence, but you can't prove anything.  That's not to say it'll never have an exception. 

So where are some areas that people sometimes demand scientific proof?  Well, global warming denialists will make arguments like that. 

You can come up with more evidence though until a reasonable person would have to believe it.  Others include medical advice.  This year they say you shouldn't eat this because it raises your cholesterol.  There will never be proof about a medical theory.  There will be overwhelming evidence, but never absolute total proof. 

Let's take the legal system.  Anybody here ever been on a jury?

Well, you probably will.   You know, get your name into.... I was called into jury duty this semester, and every Tuesday I have to call to see if there's a Wednesday trial. 

But what do lawyers try to do?  They try to prove someone is guilty.   You can't prove someone is guilty.  You can have ten eye-witnesses, and they could all be lying or mistaken.  

Male Student:  There's a movie called 12 angry men which is a black and white film, and it really addresses that theory where one person who is in disagreeance with a jury turns our everyone else's opinion on it. 

Professor:  No matter how much you prove someone is guilty of something- I'm not saying no one should be found guilty- but there's always a possibility that there's a mistake.  Maybe there was a similar looking person, or their identical twin did it, or all the witnesses are lying. 

I saw a movie about the prohibition era and all Capone.  He ran a big liquor smuggling operation out of Chicago. 

Why am I saying this?  Oh, in the movie- I don't know about the facts- in the movie they finally charge him with a crime.  They couldn't catch him on alcohol charges.  They charged him with income tax evasion.  They discovered that his operation had been systematically bribing the jurors with huge amounts of money and threats. 

And in the movie, the judge heard about that and he said "we'll switch the juries."  The jurors filed in and the judges just switched the juries because the first jury had been corrupted. 

No one knows the movie I'm talking about? 

Male Student:  I think I've seen it, but its been a long time. 

Professor:  Yeah, it was pretty good though. 

Okay, well, of course the legal system- not just in the US- but any criminal legal system would break down if you had to have absolute proof because there's no such thing.  Even now there are people on death row who have shown to be most likely innocent.  They've been exonerated shown to be probably not guilty. 

That doesn't mean you can't ever find someone guilty of a crime, but there's never absolute proof. 

Here's another kind of wild theory.  This theory goes... this type of germ can control humanity.  Do you think germs can control your mind? 

Male Student:  I have no idea. 

Male Student:  Control your mind? 

Professor:  I mean, yeah.  In a sense

Male Student:  You have things like parasites and stuff that can get in bugs brains and control them, so I don't see why something could develop to do that to humans.  It was germs as like little parasities. 

Professor:  Well, this is a one cell parasite.  It's not like a bacteria.  So you've heard about parasites that can control insects.  There's one that can make a crab take care of the baby parasites

Male Student:  Yeah, and it eats the crab from the inside out once it's done. 

Professor:  Well, you might wonder if there's.  Parasite that does this to humans. 

Male Student:  It's where zombies come from. 

Professor:  Does anyone recognize this disease?  I often wondered if I had it.  I did a kit and I don't.  

But I can always guarantee that more than one person in this class has it.  Alright, let's find out about it

Okay.  We're getting out of time, so I'm going to go straight to.... oh, I have to show you one thing about guinea worm disease.  You've all seen this on the back of EMS stuff, right?  This is a stick with a guinea worm around it, because to cure a person with a guinea worm, the only way to get the worm out of them is to wrap the worm around the stick and slowly wrap it each day until it's all outside of the body. 

It was noted in classical medicine, and this is now the symbol of medicine.   You pull it out by wrapping it around a stick. 

We can only stop the chain of transmission in lakes where people drink the water that hasn't been filtered.  We could wipe out the disease.  So hopefully that will happen. 

So next time you see an EMS vehicle, you'll know this is a guinea worm. 

Okay. 

Nobody in this class has it, but you may have something weirder- toxoplasmosis. 

Okay here's about the disease-

[Teacher reading: [On board.]  

Many people in a culture have changed personalities that can change a culture. 

The behavior of nations is dependent to some degree upon the personalities of the culture.  Changing the course of nations could change future civilizations.  So I'm suggesting that this germ could have an effect on future civilizations. 

So what spreads this strange paraite? 

Here's a hint.  Kitties spread it. 

Strike a bell? 

Cats spread this thing.  If an adult gets this parasite, they won't notice it. 

You won't feel sick though.  But an unborn fetus can catch it and it can make them blind and have some pretty serious health defects. 

Well, many people in the US have toxoplasmosis in their bodies. 

Looks like 12.3%, but according to the CDC it's 22.5%. 

Different countries- depends on climate and how many cats there are.  Korea has a low percentage.  The US is kind of in the middle.  I think Brazil is quite high. 

Here's how this disease spread.  Cats eat an infected animal like a mouse. 

[Teacher reading: [On board.]  

They're dormant and in these hard shells, but if another animals eats the dropping or gets them into their intestines, they'll hatch. 

[Teacher reading: [On board.]  

If a mouse or rat eats them, they grow inside the mouse and go to the rats brain, and they affect the rats brains to make them less fearful of cats.  That's pretty wild, but that's how it works. 

I've read that normally, if a rat smells cat urine it'll run away.  Cats like to mark their territory with urine.  So if a normal mouse smells that, it'll go real fast in the opposite direction. 

But mice with these bug will be attracted to it because the oocyst puts it in the path of the cat so it'll get eaten.  Going through a cat's digestive system and an essential part of the life cycle of the parasite. 

So how do humans get it?  They get it by handling cat litter, undercooked meat.  You've probably heard you shouldn't eat undercooked meat, especially pork. 

Here's some examples of the life cycle. 

You know, the cat drops into the cat tray, then they clean it and pick up the bug.  Or cat droppings will be outdoors and then mice and birds will eat it, then another cat eats the mouse or bird, and then that's how the germ grows and propagates. 

Other animals can eat the grass the oocysts are on and humans can eat the animal. 

Or vegetables that are now properly cooked or washed could have the same thing on them. 

But it's all based on a cat.  If the germ doesn't go through the gut of the cat it'll stop its life cycle. 

Here's another diagram.  It's all based on the cat

[On board.]  

These oocysts in the grass can end up in humans or other animals.  So we know the toxoplasma affects the brains of mice, so it's not so surprising that it does something to human brains.  It might not make us like the smell of cat urine. 

Someone in this class once suggested that maybe that's why people tend to like cats because it goes to the brains of humans and makes them like cats, because that would be good for the germ, right? 

I can't prove it's not true, but maybe not.  It's a little far fetched, but it might be true here's some pictures of the germ. 

It's a parasite- a one cell parasite. 

Here's a blow up picture of one.  Them. 

I don't know why these look so different from this one

Maybe they're in different life cycles or something. 

So what happens when you get it?  You have a condition called toxoplasmosis.  Some peugeot temporary flu-like symptoms.  A baby infected in the womb can get retinochoroiditis. 

According to one author, it's [On board.]  

However, there are some symptoms that are not as obvious. 

I got this from this paper by this guy [On board.] 

People infected.... first of all, once you get infected with it, I don't think there's a way to kill all the parasites because they're very resistant.  Once infected you pretty much have it for life. 

It causes poor motor coordination.  It causes people to be more apprehensive, less novelty-seeking.  They claim men will be less tidy in their apparel habits, and women to be more tidy.  Decreased self-control in men, increased self-control in women. 

Other authors have found other symptoms.  So really, it's hard to know whether this is exactly it, or how reliable this is. 

He and other authors have found that men tend to disregard rules more and are more jealous and dogmatic.  But women are more outgoing and moralistic. 

It almost sounds like maybe it's a good thing to get infected for some people. 

Some people have found that symptoms can increase over time.  The older you get it will increase the symptoms

If you were to look this up on the web, you could find articles like that.  I have a whole bunch of them downloaded.  They find different effects in humans.  Not all are the same, but they generally cluster in the same types of symptoms. 

So it makes mice easier for cats to catch. 

So why not accidentally manipulate humans?  It won't do the germ any good, but maybe by accident.  Maybe it makes us want to own cats. 

Who knows? 

It's thought that the germ increases levels of a neurotransmitter in the brains of mice and humans- dopamine.  It's thought that modification of levels of dopamine explain the behavioral changes found in humans. 

There are pills that people take that change the amoutn of dopamine in their brains as well. 

It's a well know neurotransmitter.  It's not hard to change the levels. 

Interestingly enough, it's thought to increase testosterone, which definitely affects behavior.  It makes male mammals more aggressive.  In humans, it decreasese caution.   It's well-known that it also reduces life-expectancy.  It definitely reduces immune function. 

Some people talk about the effects of testosterone being so pernicious that there can be such as thing as testosterone poisoning. 

Obviously it also tends to propagate the species better, but it has these negative effects as well. 

Okay, let's go from behavior to culture. 

I got this slide from a paper by a guy named Lafferty [On board.]  

Here's the thesis. 

[Teacher reading: [On board.] 

[Teacher reading: [On board.]  

These can all vary among cultures. 

Here's another supposed set of effects of the disease.  This is according to lafferty.  He says men become [On board.]  

This would certainly be consistent with increased testosterone.  Women were found to be [On board.]  

[Teacher reading: [On board.]  

Oh, here are some effects on rodents. 

They become more active.  All the better to be caught by cats.  [Teacher reading: [On board.]  

They haven't analyzed human brains, but mice brains have been found to have more dopamine.   I'll give you a chance to read this

Go ahead [On board.] 

Okay?  So I would venture to predict that people with more cats have higher rates of infection.  Surely some of you have had cats in the house?  If you didn't have any, your chances of having this are low. 

There's other ways to get infected.  If you like cats but you don't want to have it, you can get the cats vaccinated against it. 

Male Student:  Humans don't have a vaccine? 

Professor:  I don't believe there's a human vaccine.  I've never heard of one.  But you can get the cat vaccinated.  You can buy a test kit on the web and test yourself.  My family had cats, so I thought I might have it, but I didn't. 

Alright, so I'm going to predict that infection and cat ownership are correlated.  Does that mean being infected makes you own cats?  Maybe. 

Who knows. 

Some more effects that this has on people- according to this article, it increases the ratio of newborn boys to girls. 

I'm surprised.  I find that hard to believe, but maybe.  It increases feelings of guilt for both genders. 

[Teacher reading: [On board.]  

So if everyone around you has strong feelings about rules and structure, you might start to believe that too. 

According to the article, a positive association was found with [On board.]  

[Teacher reading: [On board.]  

You can imagine the implications of this sort of thing on war and politics.  Obviously, you know, the effects on testosterone could tip the balance towards or away from war. 

Here's another surprise.  They found highly infected countries tend to play soccer better. 

That may be becomes it increases testosterone levels making people more aggressive soccer players.  Let's take a look at this. 

They found this parasite seems to be correlated with winning soccer teams. 

They're referring to a recent article that states [On board.]  

[Teacher reading: [On board.]  

[Teacher reading: [On board.]  

So they found that in 2006, [Teacher reading: [On board.]  

Turns out that Brazil defeated Ghana, but their infection rate was a little higher, but 2/3 Brazilians have it. 

So here are some countries with very high infection rates. 

And they were 8 of the last 10 world cup winners. 

So it seems that having a high infection rate makes your country a bit better at soccer. 

US, here they're siting 12% infection rate- not very high, and the US doesn't do very well in the world cup competitions. 

Someone found evidence that motorcyclists are more like to have it. 

[Teacher reading: [On board.]  

So you get the idea here. 

To get even more into the chemistry of it, [Teacher reading: [On board.]  

So more tyrosine hydroxylase causes dopamine to go up.  Other things that cause dopamine to go up- cocaine, different kinds of medicines. 

It seems its been found that motorcycle fatalities have high rates of infections. 

[Teacher reading: [On board.]  

Here are some other interesting facts. 

[Teacher reading: [On board.] 

Some of them are probably viable- meaning it can grow.  There's someone thought that it could change in different contexts

Westerners are more individualistic whereas Asian countries are more group oriented.  They found that if they give drugs that kill the organisms, it normalizes the behaviors of infected rats. 

Medicines the reduce dopamine levels do the same thing, suggesting that the toxoplasma increases dopamine. 

So it seems like... I wonder if it'd be a good idea to reduce toxoplasma.  Maybe it'd make the world different.  Maybe there would be less war.  Nobody really knows. 

You can kind of imagine that certainly changes in dopamine and testosterone could have effects on things like [On board.]  

So what do you think?  Would it be a good idea to try to promote a world without cats?  That's the best way to get rid of it. 

Male Student:  Yeah, cats are mean anyway. 

Male Student:  They're mean but nice sometimes.  Then dogs are nice and mean sometimes. 

Professor:  Yeah, well, you can always get a dog instead of a cat.  

I don't know.  This is a 3/4 serious question. 

Male Student:  I mean, in a sense I don't see a need to get rid of cats, but if it was putting your life in jeopardy I could see getting rid of cats. 

Professor:  Any other opinions?  If you all could get a test to see if you were infected and it was free and didn't hurt, would you get it?  How many people would get it?

Male Student:  If it was free I'd get it. 

Professor:  Well, like I said I took the test myself.  It was $40 and it was hard to prick my finger to get the blood out.  You don't want to mess it up because then it's $40 down the drain. 

You could argue that perhaps the future of civilization is at stake if it increases the chance of nuclear war or something like that. 

So you can get tested.  And you can get treated.  They even found that if you treat rats they start to behave better or different.  You can vaccinate your cats and demand that politicians reveal their test results. 

Supposing two presidential candidates and you didn't know which one to vote for.  Maybe if they knew if they were infected it would skew the votes. 

Cover your sand boxes.  Why?  Cats, when they don't have litter boxes they like to go in sand boxes.   Finally, before I let you go, own rats instead of cats.  They make great pets! 

They're fun.  I had a girlfriend who had a pet rat once. 

Here's somebody with a pet rat.  They like watermelon and they like to climb on your head. 

You can even put cute little clothes on them. 

And they can get sick but they don't spread toxoplasma.  So there's your lesson.