Dawkins: You sort of feel that if doctors
could get that one point, everything else
would follow? It's rather a profound point
in a way. And another way to put it would
be to say that a lethal gene or a gene that
makes you die when you're young, is never
going to get into the next generation.
But the very same gene, if it has its bad
effect a bit later, it's got a better chance
of getting into the next generation.
And if it doesn't have its bad effect
until you're one hundred, then it's
gonna get through all the time. And so,
we are a kind of walking dustbin of late,
late maturing lethal genes. And, if any
of us had a gene that made us die young,
well, none of our ancestors had a
gene that made them die young.
Nesse: And indeed. How many of your
grandparents died before reproducing Richard?
Dawkins: Yeah, very good point. (laughter) Nesse: (laughter) Right.
Dawkins: What about mental health, and
can we bring Darwinism into that?
Nesse: We certainly can, and many people
imagine that it's just them and their family
that have problems with depression, alcoholism,
anxiety, and schizophrenia and the rest (unintelligible).
The World Health Organization data shows
that especially for women of reproductive
years in modern countries, more than half
of all of the medical disability and early
death is from mental problems, mainly
depression and anxiety disorders. But let's
take anxiety for a second. Wouldn't it be
great if we didn't have any anxiety?
We would just be completely relaxed and
mellow all the time? Except that we wouldn't
have prepared for this program at all, and
we wouldn't have done our studies, but it's
worse than that. Imagine if we were at a
watering hole in Africa, well before anybody
learned to read, and a lion comes by, and
we run like mad. But there's some variation
isn't there? Some people run at the least
hint of a lion, some people run when the
lion's coming near them, and other people
don't run until the lion is right on top of them.
And you can see where this is going. The ones
who run away when the lion is a long ways
away never get any water. That's really bad
for you. The ones who wait until they can
smell the lion's breath, often become lunch
for lions. It's those people in the middle
who do best. But now we're back to the
smoke detector principle. Imagine you hear
a sound behind a rock at that watering hole.
How loud does the sound have to be to
make you run away? You don't know whether
it's a monkey or a lion. How loud does that
sound have to be? And you can actually
calculate just how loud it should be.
If the cost of running away is say, a
couple of hundred calories, and the cost
of not running away, if that sound comes
from a lion, is two hundred thousand calories,
then you should run away whenever the
sound indicates the probability of the lion
being their is greater than one in a thousand.
This means that the majority of times you
have a panic attack and run away, you won't
need to. But it's still perfectly normal.
I treat patients with panic attacks,
quite often. It's a very treatable psychiatric
problem now. And I had never really
grasped what was going on until I took
this evolutionary view, and realized that
the whole system was designed, the whole
system was shaped by natural selection,
to go off with many false alarms. And that's
why we're all so prone to anxiety that
really doesn't help us, most of the time.
Dawkins: And some people have their
smoke detectors tuned a little bit more,
Nesse: they certainly, they certainly do. Dawkins: (unintelligible) than others. Yes.
Nesse: And they have advantages as well
as disadvantages. My patients find this
wonderfully empowering. They've always
thought that they were just anxious people
who weren't as good as other people.
And when they finally learned that, in fact,
they have real advantages over other people
because they're more sensible in some ways,
Nesse: that helps them quite a lot. Dawkins: I was going to ask about that
Dawkins: because a lot of what you're
saying is explaining why we go wrong in
these ways, and I was going to ask you,
how does it actually help to cure people?
And you've just given one reason,
which is that your panic attack
patients actually are comforted by
having the explanation given them.
Nesse: Not only comforted. About 20% of
Nesse: them get cured. Dawkins: Get better, yes.
Nesse: Yes. And previously, they would say
"I think it's cancer doctor, I think I have
a brain tumor, I think I have heart disease,"
and I would say "No no no, the tests show
that you don't have that. And they'd say
"Yes, but I still could." But they didn't really
understand what panic attacks were. Once I
started saying "Listen, panic attacks are
false alarms in you're getting away from
lions system. And because they're false alarms,
running away and getting out of the store
doesn't do you any good. In fact every
time you get out of the store and run away
from your own anxiety, it makes it worse."
But one out of five patients says
"Oh, now I know what that is. I'm just going
to ignore it." And they go about their lives
and they're not bothered by panic anymore.
Nesse: Very very practical application. Dawkins: I suppose one could say, well,
Dawkins: there aren't any lions, I mean...
Nesse: Nowadays it's not all that useful,
although we still do have fatal kinds
of dangers sometimes, not lions but
more likely other people, and other
kinds of dangerous situations.
Dawkins: Yeah.
Dawkins: Randy in a nutshell, what is
Darwinian medicine, and what can it tell us?
Nesse: It's very simple. It's using everything
we know about evolutionary biology to
prevent and cure disease. This means
that there are a lot of things we need
to do very differently. Some we've already
been doing very effectively. We do evolutionary
genetics quite well, and we're doing it
better and better. We're using evolutionary
biology to understand bacterial evolution,
Nesse: and antibiotic resistance Dawkins: Oh yes.
Nesse: It's already been done well, and
we can talk more about that in a minute
if you'd like. But this larger picture is
what George Williams and I have tried
to get across. It's this sense for what
the body is as a body, not a machine.
And really all it comes down to asking
a question that has not been asked as
seriously as we'd like to see it asked.
That question is, "Why isn't the body better?
Why didn't natural selection make us better?"
And to simplify things, we list six
possible reasons. The first one is that
other things evolve faster than we can,
so it's no surprise we still get infections.
The second one is that the environment
is different now than it used to be, so,
or we can't evolve fast enough to keep up.
So the first two are because we can't evolve
fast enough. The next two are because
natural selection can't do everything.
There are a lot of constraints on it, it
can't go back and start over again,
and there are going to be mutations
creeping in, so the information store
is going to get corrupted. Just can't
do better than that, that's natural
selection, stuck with it. Closer related
are tradeoffs. Even in machines, like in
bodies, nothing can be perfect because
if you made it absolutely perfect, the cost
would be too great. You could make a car
that would go about a thousand kilometers
on a tank of gas, but the whole backseat
would be taken up with the gas tank, and
it would blow up every time it got hit by
another car. The final two explanations
are not really explanations for why natural
selection didn't make us better, it's
explanations for how we misunderstand
the body. In particular, we think that the
body was shaped for health, and of course
it was not shaped for health, it was shaped
for maximum reproduction, and this explains
a lot. And the last one we've just been
talking about is defenses. Fever, pain, nausea
vomiting, all the rest are not diseases.
They're defenses shaped by natural selection,
and their regulation has been shaped by
natural selection. So these six things are
possible answers to the question about
why natural selection has left our bodies
vulnerable to disease. Our bodies are so
fabulous in some respects, our heart keeps
beating and never takes a five minute
vacation for decade, after decade, after decade.
That's astounding. Our eyes work so well
late into life for most people. But we have
an appendix, we have wisdom teeth, birth
is difficult, many people get nearsightedness,
and the combination of some things being
so perfect, and other things being such
botched jobs, is what should make us all
sit up and take notice that this is not
a machine. This is something that's been
shaped by natural selection that has a lot
of vulnerabilities built in, that can be
explained only by how natural selection works.
Dawkins: If you had your way, could you
retrain doctors to think differently, and
how differently would they actually act
when they're faced with patients?
Nesse: You know, there are a lot of specific
things that doctors can differently as
they understand natural selection better.
For instance, using drugs to block pain
and vomiting. If you think more evolutionarily
you'll do that slightly differently, mostly
of course you'll do the proper research
to get the answer. I don't think natural
selection actually tells doctors "Practice
differently immediately." What it gives
doctors is a more accurate sense for what
a body is. So when a doctor sees aging
many of them think of a machine breaking
down because parts break. But once you
start recognizing that that's not just
what's going on, that every aspect of the
body breaking down is involved in some
tradeoff that probably has advantages,
we talked about how practical this is,
we're not finding specific genes that are
involved in aging. Would it be very wise for
us just to go, knock out those genes? We
soon may well have the capacity to do that.
If you're thinking just from a mechanical
point of view, that sounds like a good idea.
But if you understand the body from an
evolutionary point of view, you'll hesitate
carefully, and say "We've got to study
this before we start knocking out genes
that natural selection has preserved."
Dawkins: Why do males tend to
die younger than females?
Nesse: Oh yes, you and I, we're
members of the feeble sex aren't we?
I think it's not quite fair.