Behavioral genetic methodologies from twin and adoption studies through DNA analysis will be described and applied to address longstanding questions about the origins of individual differences in behavioral traits.
Unit 1 Office Hours Video
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Introduction to Human Behavioral Genetics
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Unit # 1: Course Introduction and OverviewOverview: Unit # 1 provides an overview to the field of human behavioral genetics and to this course. We will begin by discussing the early history of the field and how behavioral genetic research influenced and was influenced by the eugenics movement. Once this historical context has been established, we will define the field of behavioral genetics and use this definition to provide an overview of the course. This week’s lectures will end with two case studies that illustrate the importance of behavioral genetic approaches. The first is the famous John/Joan case, where one member of a monozygotic twin pair was raised as a boy and the other as a girl. The second is the human genetic disorder Phenylketonuria (PKU), which has been recognized as a paradigm of human genetic disease since its discovery in 1934.Unit Objectives: At the end of this unit you should know• The history of the founding of the field of behavioral genetics• What the eugenics movement was and how it impacted psychology and behavioral genetics• What the field of behavioral genetics covers• How the John/Joan case represented the extreme of the “Blank Slate” mentality within psychology• Why Phenylketonuria is considered a public health success and model of human genetic diseaseLecture Modules:A. The Nature-Nurture Debate and Founding of Behavioral GeneticsB. The Eugenics MovementC. What is Behavioral GeneticsD. The John/Joan CaseE. Phenylketonuria (PKU) F. Huntington Disease (Supplemental)
Meet the Instructors
Matt McGueRegents Professor
Psychology
Welcome to unit one, the first week's Office Hour.
again, I'm Matt McGue.
We think that the course has been off to a very good start, a very lively start.
We thank you for participating in the course.
And these Office Hours will be weekly events
that we post by Tuesday, sometime on Tuesday.
And the office hour is actually going to be run,
or organized, by the TA for the course, Bridget Carey.
So Bridget, why don't you introduce yourself.
You have a little bit of an introduction on the, the web page
for the course, but let the students know a little bit about you.
>> My name is Bridget Carey.
I'm the TA for the course.
I grew up in Boulder, Colorado, and that's also where I did my undergraduate.
Degree at the University of Colorado, Boulder.
Moved out to the University of Minnesota a couple years ago to enter
the Personality, Individual Differences and Behavior Genetics
program here at the University of Minnesota.
So, I'm here if you have any questions.
>> Okay, great.
So the way this works, is Bridget reads the questions on the website.
>> Mm-hm.
>> And then you organize.
>> Yes.
>> What, what you think we should talk about here.
Even though we call it an office hour, we probably won't go a whole hour.
And then hopefully, you don't, that's okay with you guys.
So, I guess, why don't we go ahead and get started and you can tell
us a little bit about what you're trying to...what the goals of Office Hours are?
What are you hoping to accomplish by holding these office hours?
Okay,well the first thing maybe I should point out
is that,which is probably obvious to anybody who has
been on the forms, is that there's been a
lot of activity on the forms thus far this week.
And that's great.
I, in fact, I came away extraordinarily
impressed with just the quality of the postings.
I learned a lot, by following the postings.
So the first thing I would encourage people to do is go on there.
There's a lot of interesting topics to follow.
And people bring in a lot of information.
This particular thread, the Office Hour thread what
we're hoping to do here is as the
course progresses, we will I don't want to say the course gets more difficult but it
will become more technical in the sense that
we'll begin to bring in genetics and we're
going begin to bring in statistical genetics and
we're going to talk about specific studies in detail.
And I think students are going to begin to
have questions about the technical aspect of the course.
>> Hm.
>> Now normally right?
We teach courses and the students just raise their
hand, and then we try to answer their question.
Well, that's not possible here, so we give
the participants in this courses vehicle, of posting something.
On the Office Hour thread that you, you monitor and then, and then you organize.
And so I guess what we're looking for here are
things where we haven't done a good enough job maybe
in the lecture posting to really explain some concept that,that
the student, or the participant would like to know more about.
>> Great.
So.
>> Okay.
>> A good place to post kind of clerical questions, to clarify ideas, and.
>> Yeah, to clarify and, you know, if something's ambiguous, if
there's a technical term that the definition is not really crisp.
And that actually reminds me that one of the things that Bridget put together.
Is a glossary.
>> Mm-hm.
>> And this is a dynamic document.
That is she put together a glossary for the first three units, the
first three weeks, and that's again to facilitate your learning of the material.
That glossary then will be updated each week as we go along.
And that will be, it will be posted somewhere, it's not
on the website yet, but maybe by the time this get posted.
The glossary will be posted as well.
But, that also a learning aid th, that participants have access to.
>> Wonderful.
Well why don't we get right into
some questions that we've received from students.
And the first one has to do with statistical requirements for the course.
[BLANK_AUDIO]
>> I was hoping maybe you can talk a little bit about what sort
of statistical knowledge is necessary to really take the most out of this course.
>> Okay.
Yeah, that's a good question.
The.
Really the only prerequisite that we had for this course, that I had for
this course was that you have some
background, in statistics, some introductory exposure to statistics.
And I recognize that for a lot of people that might have been a long
time ago, and it, and it maybe for
some people actually create some anxiety surrounding it.
I actually don't think the statistics here,
you've taken the course in behavioral genetics.
>> I have.
>> It, it, I don't really think it's that formidable, do you?
>> No.
>> [INAUDIBLE] No.
>> No.
>> Yeah.
The, what, the reason for the requirement, and usually when we, and you'll also begin
to see, and, and I would think by now, the second week's lectures are posted.
By now.
And if you look at, for example, the lecture where we talk about
the different ways of assessing twin similarity,
there we begin to get in statistics.
I recognize that for some of you we haven't
had that for a while, so I tried to provide,
this is not a course in statistics, but I do
try to provide a little background on the statistical concepts.
The reason for having the statistics requirement though is
that really I think in order to get any,
into any depth in to this subject, you really
have to read or understand the primary research literature.
I don't want to filter everything and give you my interpretations.
I would like to, of course you're going to
get my interpretation but I would like to give.
People.
These are what the studies found.
This is how I interpret it.
You may come up with different interpretations.
But to understand what those studies found, you could,
you're going to need to have some background in statistics.
Again, I'll try to provide that context for you.
It's not, you don't need a high level of statistics for this course.
Simple things, like understanding when statisticians talk about testing
the hyp hypothesis, the p-value for a test of a
hypothesis, saying something is statistically
significant, those types of things,
and, and understanding basic des,
descriptive statistics, like correlation coefficient,
>> Mm-hm.
>> The mean,.
The percentage, the probability, those kinds of
things probably most people are very familiar with.
Again we'll try to provide them with context.
And the office hour is a completely appropriate place to
raise questions if you think the statistics is very challenging.
>> Absolutely.
>> We'll elaborate on this here.
>> There are a lot of questions on the forum about the John Joan case.
>> Hm, mm.
>> And so, I guess to start off, what were
you really trying to show by, by talking about this case?
>> Okay,
so the, the Johnny, there was a lot of discussion about
John and Joan, and I guess we could have anticipated that.
Although not, again I thought I was extraordinarily impressed with
just the depth of the way people were thinking about this.
>> Oh absolutely.
>> The different implications, and how people went out on the web
and they got resources to read more about the John Joan case.
My intention in introducing it.
In the, the first week of lectures is, was pretty simple, really.
And that is, I think that from our
perspective, it may be difficult, I might be wrong
on this, but it may be difficult to appreciate
how dominant the blank slate mentality was within psychology.
And I think with the John, for me anyway
with the John Joan case really does, is it illustrates.
Let's take the blank slate mentality really to the extreme.
Could we make someone a boy or a girl just by the way they were socialized?
I think one of the rea, what you get
on the, the discussion forums is people are amazed.
At least some of you were really amazed that people used to think that way.
But when I took introductory psychology in the 19,
mid 1970s, and maybe the early 1970s, to be
honest I learned about John Joan, and I sat
there and thought, well, wow, you really could do this.
And it wasn't only til later.
So,the John Joan from my perspective
was really to provide a historical illustration.
I also think historically it's something
that people in psychology should know about.
It's I think an important case study.
But the last thing I should point about this is that it is a case study.
It is an anecdote.
Anecdotes in science, my opinion, anecdotes
really can't prove nature or nurture.
>> Mm-hm.
>> Anecdotes are very powerful.
They, they personalize things for us.
They help us think about things.
They provide insights.
But we really can't say whether John Joans' behavior or Brenda's behavior
or David Reimer's behavior owed to nature versus nurture, because it's an anecdote.
I, I forget who said it, and maybe you'd know, Bridget, but
somebody famously said that the, the plural of anecdotes is not data.
In a quantitative science, in behavioral genetics
is a quantitative science we want data.
Anecdotes, and you'll see in the second week I introduce another anecdote.
I like anecdotes.
They're interesting stories.
But they're not the type of thing that
can prove one scientific argument over the other.
So I don't want to.
Maybe I should've been more cautious.
When I introduced it to let people know that I
was thinking of it this way, I don't think that
from our vantage point we could really say why John
or Joan behaved in the way he or she did.
>> Well, it really did generate some good discussion in our forums.
>> Yeah, yeah, yeah.
>> Somebody wanted to know, what are the biological mechanisms that make a
child, well made Brenda, more masculine than maybe the other girls her age?
So, al-, although we, we might not be able to tell in Bruce
Brenda, David Reimer's case, what was the underlying cause of his and
her behavior, we do know and actually, I think some of the
classic studies on this date back to even the time of John Money.
We do know something about hormonal
influences on behavior, on gendered behavior.
Maybe some of you probably know about this already.
Endocrinologist or behavioral
endocrinologist distinguish between organizing
effects of hormones and activating effects of hormones.
In the general population when we talk about sex hormones, hormonal
and influences on behavior we tend to focus on those activating effects.
The, the effect of, of circulating levels of hormone that
are relatively transient they, they occur at puberty or postpubertal.
In fact, probably the most powerful effect of hormones are the organizing effects.
These are effects of hormones that occur very early in life.
It's an oversimplification, but in humans,
the default developmental trajectory is a female.
If someone inherits a y chromosome, or more specifically, a certain
region of the y chromosome, that initiates a cascade of events,
the development of the testes, the secretion of androgens, male hormones,
that then takes the fetus down a developmental trajectory to become male.
>> Mm.
There's a surge of those male hormones early, prenatally, in humans.
It turns out it's in the first trimester.
In other mammals it occurs at different periods of time.
That early surge in hormones is now established
to have organizing effects on the developing fetus.
It organizes the brain.
Somewhat differently in a male and female.
Because of that early exposure.
We know this now, infact the classic, the original study
on organizing versus activating effects of hormones was done in 1959.
Right around the time of money.
By a group I think the first author is named Phoenix.
And what they did, I think it's guinea pigs,
but they actually manipulated that early surge of androgens.
In any case, David Reimer, prenatally would have experienced
that early surge that would organize his brain differently.
On average, than a female brain.
Male and female brains aren't that different, but they do differ.
>> Um-hm.
>> And they differ because of that early exposure.
So even though he was castrated at age 2 and wouldn't have experienced
the activating effects of androgens, he
had that early exposure, those organizing effects.
So if he was male in his interests and that.
We would presume it is because of these organisms.
>> So another big topic was phenylketonuria and this is a little
bit more of a complicated topic to be covering in the first unit.
>> Mm-hm.
>> So I guess what.
What were you hoping to get out of introducing it so early on?
What did you want to show?
What did you want the class to take from it?
>> Yeah, phenylketonuria for me illustrates a lot of things, and I won't
go through all of them now because I won't remember every one of them.
But I'll try to hit what I
think are the most important things about phenylketonuria.
The first thing is, I think it's an antidote.
To the thinking that, if you're studying genetics, the point of
genetics is to tell us what we can't do anything about.
There's some, for some reason, that meme has pervaded within psychology.
It doesn't exist in medicine.
If you talk to medical geneticists, or human geneticists, they don't think of.
Identifying a disorder as a genetic disorder means you can't treat it.
But for some reason in psychology we think
if something is highly heritable we can't change it.
Phenylketonuria really shows that isn't the case.
In the case of phenylketonuria by identifying.
The underlying genetic defect, it provided the medical researchers a way of not only
identifying people with phenylketonuria early, which is
important, but also to develop an effective intervention.
So it's a beautiful illustration.
I think maybe it's a little bit overused, but
I think it's an important concept as we go forward.
Genetic doesn't mean non-maliable.
We're not in the business of doing, at least I'm not, and I'm sure you're not
either, doing genetic research to say okay, once
we've shown something's genetics, we leave that one alone.
Because we can't do anything about that.
We can't do anything about schizophrenia or intelligence or whatnot.
That's not the case.
So I think that was the first reason it's important.
The second reason it's important, and this is a topic
that we'll begin to talk about more and more as
we go through the course, and particularly it'll be introduced
in the third week, is the notion of gene environment interaction.
That both your, it's, certainly when you talk about behavioral phenotypes.
Both your genotype and the environment
you're reared in are going to be important.
Our, the challenge for us, in dealing with something as
complex as behavior, is to understand how those two combine.
>> Mm-hm.
>> In the case of phenylketonuria we know, and
so we can work out the pathway and everything.
It's a beautiful illustration.
That they're both important and once you get get down to the
mechanisms of phenylketonuria, who cares about
heritability or anything at that point.
We know it now, so all those arguments are
beyond us because we've gotten down to the mechanism level.
I kind of think that's what our goal is, our goal
should always be we may not achieve it in every case.
To, to try to work out the mechanisms as they've done with PKU.
>> What's a connection between brain
maturation and the sensation of PKU treatment?
>> Okay, so
in the case of, so the, the neurotoxicity in phenylketonuria is due to.
The inability to metabolize phenylalanine and
then it builds up this toxic substance.
Prenatally although the fetus can't, if the fetus
has phenylketonuria the fetus can't actually metabolize phenylalanine.
The mother's.
Well, would be a carrier, probably not affected,
so she would be able to metabolize it.
So in terms of early brain development you're ok.
Somebody with phenylketonuria is usually detected now, throughout most of
the world, usually around the time of just after birth.
And by then there's really not going to be
any neurological damage if they go on the diet.
It was once thought.
And I think, I don't know the exact dates.
But it was something like the diet is
actually a little bit difficult to stay on, right.
It's, phenylalanine is in absolutely any, almost any protein you eat.
Pizza, beer, any Coke.
But not Coke but Diet Coke.
Coke probably doesn't have any protein so.
I don't know [LAUGH].
But
the, so it's hard to keep kids on it.
because they have to have all these special lunches and everything.
And they can't eat the, the other things at the parties that they go to.
So they used to take them off at about age seven.
And the notion was you can take em off at
age seven because that, by then the brain was fully developed.
And there was really no need to be on the diet any more.
Well I'm not a neuroscientist,
but neuroscientists developed, well known scientists
have now shown us that really the brain continues to develop.
Throughout adolescence into early adulthood.
Now I actually don't, do you know?
I don't know when, when they really, if there's a consensus when it ends.
>> Yeah, I don't, I haven't heard a solid consensus.
>> Yeah.
>> I thought it was late adolescence, early adulthood.
>> Yeah.
So, in any case, for sure now,
the recommendation is to maintain a very rigid,
which is difficult, and becomes more difficult as
you get older, in teenage years and those.
To, to maintain a real tight control over phenylalanines.
Certainly through early adulthood and the development of the brain and in fact
there's recommendations that you should be lifetime on a reduced phenylalanine diet.
>> So, you introduced the topic of
maternal PKU briefly when speaking about it.
But there have been a couple questions- >> Okay.
>> Asking to get a little bit more detail about that.
>> Okay.
Sorry, I, I think maybe I didn't define maternal PKU.
So good catch me on that one.
So what maternal PKU was.
When they first, this would've been in the 60s I guess.
When they first, implemented the reduced
phenylalanine diet for individuals with PKU.
It went great, right.
And if you've watched the video, it's
really impressive how powerful that intervention is.
Women who were successfully treated for PKU then would have gone off
the diet as children when they're five, six, seven years old, whenever.
And then when they came along and had their own children.
Now the woman would have carried two copies of the, the mutation.
It turned out that a 100%, virtually a 100% maybe a little bit less than that.
Maybe 96%.
But almost every child that one of
those women had were severely intellectually disabled.
Now it turned out that not all those children
had in fact very few of them had phenylketonuria.
They would have been detected at birth and put on the same diet.
Yet they were severely brain damaged.
One of the unfortunate consequences, or unanticipated
results of the early treatment, is that
when females went off the diet and
then became pregnant, because they couldn't metabolize phenylalanine.
Their bloodstream was supplying a very
phenylalanine rich diet to the developing fetus.
That proved to be neurotoxic.
So maternal PKU is that when the
mother has phenylketonuria that's been successfully treated.
Becomes pregnant, because she can't metabolize phenylalanine.
If she's not on a restricted phenylalanine diet, she will
expose her fetus to very high levels of phenylalanine, and that
fetus is very, very likely, then, to suffer intellectual disability,
even though the, the fetus does not have phenylketonuria, per se.
>> Great.
>> Okay.
>> Well, I think that wraps it up for our first weeks Office Hours.
Unit two is starting this week.
So send in your questions and we'll address them next week.
>> Okay, thank you, Bridgette.
>> Thank you.
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