Throughout history, the vast majority of people around the globe have believed they have, however defined, a “soul.” While the question of whether the soul exists cannot be answered by science, what we can study are the causes and consequences of various beliefs about the soul and its prospects of surviving the death of the body. Why are soul and afterlife beliefs so common in human history? Are there adaptive advantages to assuming souls exist? Are there brain structures that have been shaped by environmental pressures that provide the foundation of body/mind dualism that is such a prominent feature of many religions? How do these beliefs shape the worldviews of different cultures and our collective lives? What is the role of competing afterlife beliefs in religion, science, politics, and war? This course explores several facets of this relatively unexplored but profoundly important aspect of human thought and behavior. The course consists mainly of 70 to 80 minute lectures, typically broken up into 3 segments, recorded from a course offered by Rutgers University School of Arts and Sciences. These videos include slides and some embedded video clips. Most lectures are accompanied by slides used during the lecture, also including recommended reading assignment which may provide additional opportunities to reflect on your studies. Due to the lengthiness of this class and natural progression, the online course has been separated into 3 units, this is Unit 3.
The Evolution of the Human Brain Part B
Loading...
From the course by Rutgers the State University of New Jersey
Soul Beliefs: Causes and Consequences - Unit 3: How Does It All End?
74 ratings
Rutgers the State University of New Jersey
74 ratings
From the lesson
The Evolution of the Human Brain
Meet the Instructors
Prof. Daniel M. OgilvieProfessor of Psychology
Psychology
Prof. Leonard W. HamiltonProfessor of Psychology
Department of Psychology
One of the things that this brain development has to do is to
send long fibers from one place to another.
So the basic structure of a neuron typically, is the cell body located
here and then some long fiber that goes out and makes a connection someplace else.
This is written in the instructions of the DNA, where they're supposed to go.
Now you may recall that the brain has lots and
lots of neurons in it and
from the time of conception until the time of birth,
about a million new neurons are developed every minute of that nine month period.
They have to find their way to the proper location
and in that process, there's some competition involved.
You've all been engaged in a similar competition, in the past week or so,
when you went onto your computer and tried to target courses for the spring semester.
In many cases, you would find out that you got there a little bit too
late and it had turned from from green to red.
That's kind of a bummer and the same thing happens with neurons.
When you have instructions in the DNA that says you need to go from here to here and
make a connection, when that connection is made,
it's sort of a handshake type of agreement between both the sending cell and
the receiving cell and they say okay, good, this is going to work.
Now some other neuron from that same region comes up here and
sorry, there's no place to connect.
This is worse than having a course close because a cell dies,
if it doesn't make the connection.
To accommodate that, we have something called programmed cell death.
Programmed cell death, where cells are supposed to die.
So the way this works is that by the time you were born,
you had created a million or so neurons every minute
during gestation period and by the time you were born,
about half of all the neurons formed in your brain had died.
They had died, and there's a good reason for that and
it kind of goes back to what may be an apocryphal story, or it may not be, but
supposedly, someone once asked Michelangelo how you could start out with
a big block of marble and end up with this beautiful statue of The David?
He replied that it's really very simple.
You just take a hammer and chisel and
you chip away all the parts that don't look like David and
then you have the statue, that's kind of what happens during brain development.
You have a whole bunch of neurons being developed going out trying to find
locations, and if they don't look like this final product,
they don't look like the blueprint, they shrivel up and die.
I have a little jar of rice here, it's the cheap stuff,
small grain, white rice that's probably not even good for
you but anyway, you all know what rice looks like even if you can't see this.
How many grains of rice do you suppose might be in here?
There's no prize but feel free to guess.
What do you think?
You.
>> [INAUDIBLE] >> How many?
Five hundred?
>> Five hundred.
Anybody else?
Take another guess.
How about you, what do you think?
>> Nine hundred.
How about you?
Two hundred.
>> You guys are so, so wrong,
there are 5,000 grains of rice in here.
Now, let me say that it's about 5,000,
I didn't count out 5,000 grains of rice and put them in here but
I did very carefully measure a couple of teaspoons, and
so this is close to 5,000 grains of rice.
Now the brain.
Has that many neurons in it, give or take.
See different estimates but about 500 billion.
Now the only other place you see these kinds of numbers is with national debt.
>> [LAUGH] >> We don't understand that any
better than we understand the brain but
I want to give to you some sort of a feeling, since we don't understand those
numbers, some sort of a feeling for how big the brain is.
If you take these 5,000 and
then figure out how big the container would have to be to hold this many, i.e.,
how big our head would have to be if our neurons were the size of grains of rice.
We'd have a lot of trouble fitting through doorways because
if you get that number of grains of rice, and start
pouring them in to the football stadium, by the time you get to that number,
you will have filled that stadium higher than you're head.
The brain is huge and
each of these neurons may have as many as 1,000
interconnections with other neurons.
Carl Sagan, whom you've saw in a video a few weeks back,
wasn't afraid of big numbers and
he made the calculation that if you look at all the synapses in the brain and
consider the possibility that they could be either active or inactive, how many
states of the brain could you have, just viewing the brain as a computer?
The number of different states that the brain could be in is way,
way, way larger then the number of electrons and
protons and other elemental units in the entire known universe So,
what that means is that this big, gooey disk drive,
I guess you might call it, is perfectly capable
of holding all of your memories, all of your language.
All of the things that you will learn in your college education, your love for
your grandmother, your contempt for the neighbor's cat, it's all in there and
there's plenty of room left over.
So we end up as they told
us with a structure that is breathtaking in its complexity yet
frugal in its variability so we can perhaps begin
to understand some of the aspects of this brain.
Now I've talked to you a couple of times, about MacLean's triune brain.
The reptilian brain serves basic functions.
The more complicated old mammalian brain in
the new mammalian brain,
which in us looks like this, with all of it's wrinkles in the cortex.
The reason why the cortex is wrinkled is because it
has a lot of things that it has to do.
And if you look at the cortex with a microphone, no,
you use a microscope, actually.
It works better than a microphone to look at the cortex.
If you look at it with a microscope you will see that it's a highly
structured set of cells that are in layers and
communicate with each other up and down the layers.
If you were to take this cortex, if you were able to take the cortex and spread it
out, smooth out the wrinkles, it would be about the size of a queen size bed sheet.
Not nearly that thick.
But it's a big sheet-like structure.
And if you want to get it inside a human skull, what do you have to do?
You have to just stuff it in there, and it ends up being wrinkled like this.
So it's just a big surface area.
And so we have this amazing structure,
layered structure where things get added.
Starting out, evolutionarily with some pretty simple stuff and
adding layer after layer after layer of more complicated things on top of it that,
of course, allow us to do more and more complicated things.
And when you look at that.
When you look at the brain, you have to just think that
such a grand orchestration could not have occurred by accident.
It's one of the things that the naysayers will say, you can't get this by accident.
But, the fact of the matter is, we kind of did.
With the two basic rules, natural variability and
natural selection, That slowly, slowly,
slowly built up to this complicated structure.
Now I've got an image of a watch or a clock there.
And here's an important thing to know about evolution, and it's
easily overlooked because we kind of tend to take a teleological point of view and
we kind of, it's easy to think that this human brain is the end product and
that's what was in mind all along with a process of evolution to reach that.
But no, that's not the way it works.
It's not the was it has worked.
If you could set the clock back 40,000 years,
40 million years, if you could just set
the clock back to all of the conditions that were present at some previous time.
Everything exactly the same as it was then and start the clock ticking again.
Those two processes, natural variability and natural selection would work, but
because of all of the random variations and the other things that could
happen we would not end up with something that looks like this.
It just absolutely would not look like this.
It might be better.
It might be worse but the rules that apply do not have that in mind.
That's just what has happened.
So one of the things that I want to talk about is the question,
is the human brain special?
I mean we think we're special And
we view ourselves above all of the lower creatures and
everything, and view ourselves as being specially creative and
all sorts of high order things.
So is there any reason to believe that the human brain is special in any way?
I think we have to answer yes, that it is special.
And it's not that our brain is just bigger, faster,
sharper maybe than the brains of other creatures.
Well what we are going to see are differences in process and plasticity.
Process and plasticity that kind of move us off
the charts in some ways from other creatures.
We are a very visual organism.
We kind of have that as our primary source of
information as we go through our daily lives.
So I want to talk a little bit about the visual system because it's probably easier
for you to understand.
And to give you a demonstration of how the human brain is very
special indeed in the way we process visual information.
Let's begin with the moth.
You've probably all been out on a summer evening and
seen a whole swarm of moths circling around the street light.
You might have even wondered why they're doing that, or you might not of.
It might just be something that seems a little bit curious.
But back in the day when we hadn't messed things up quite so much, on this planet.
Before Thomas Edison invented his famous light bulb and things like that.
Life for the month was pretty easy.
The moth would go out at night and pick out some light source,
most likely the moon and the moon is over the moth's right wing here.
And it goes out an goes to work and do whatever moths do and
then turns around put the moon over the left wing.
And comes back unerringly to home, works like a charm.
But now when the moth goes out and sees the brightest object in the sky which is
a street lamp, puts that over its right wing,
it ends up with an ever decreasing spiral until it's going round and round and
round and round, and usually dies there at the street light.
Well that's kind of stupid isn't it?
Why doesn't the moth just figure out that that's
not an appropriate aid to navigation and do something different.
Well, that's because the moth's brain is so
small that you can't really see it with the naked eye.
It can't really process that kind of information.
There is a famous experiment that was done with frogs,
entitled what the frog's eye tells the frog's brain.
Basically these researchers monitored the fibers going in from the frog's eye
to the frog's brain, and they found out that the frog has
some pretty basic systems built into the eye of the frog.
And one of them was just the ability to see a line of contrast and
maintain its orientation, so it's really kind of a horizon detector, if you will.
Just a simple system in the neurons that connect the visual receptors in the eye.
The frog also has a dimming detector, so if the frog is sitting
there on its lily pad or whatever and all of a sudden a shadow swoops across,
it's a good chance that shadow might be some bird of prey like
the green-backed heron, here holding a frog in its mouth.
And the frog then has the opportunity to escape from that predator.
And the one most famous, of course, is the frog's ability to see a small dark object
that's moving and flip out its tongue and catch it for its lunch.
If you give a frog a bowl full of freeze dried flies that are dead
it will starve to death because it doesn't know how to eat, a fly that doesn't move.
If you put that fly on a little string and
wiggled it in front, it'll catch it and eat it.
So some pretty basic simples that worked like a charm for the frog,
and it's pretty much all taken care of in the eye, and
the eye then tells the brain what's going on out there?
Now let's move to the little chick.
One of the things that a chick has
to do right away after it hatches is
learn to peck at seeds and eat.
How good are they at that?
Well, a psychologist asked that question and
the way he asked it was to take a little block of paraffin and
to anchor a seed in the middle of some seeds that were loose.
Can't see that anchor very well, I'll put a little mark on it there.
And on the first day or two, after the chick
has hatched, it will peck all around that,
not being terribly accurate in hitting that seed.
But now look what happens after about a week,
the chick has become a much better marksman, and
has developed eye-beak coordination, and can just zero right in on that.
Cool, and
you can all imagine how the chick is doing that because you all have at one time or
another done some sort of a target practice, whether it's a bean toss or
a bow and arrow or whatever, and you get better at it through practice.
Now look at this, Professor Hess put goggles on the little chick,
and they're not just any ordinary goggles,
they're goggles that shift the chick's vision about 15 degrees to one side.
And now we'll put a little marker on it again, this is the target and
the poor little chick with his vision shifted,
pecks about 15 degrees off to the side all around out here where the seed isn't.
And over the course of a week, and I know this is hard to get your head around,
but over the course of the week the chick, just like it did up here,
develops much better eye-beak coordination and
is pecking in a very tight pattern, not where the seed is.
And the chick will never learn
to adjust its pecking.
It's just the way the chick is wired up.
If the vision is distorted and goes over here, then that's just the way it is and
it doesn't have the capability of making that correction.
Now you have all probably in one of your seventh grade science classes or
something, seen the little demonstration where you plunge a yard stick
into an aquarium and it looks like the stick bends where it goes into the water
because of the different refractive indexes.
And when you look at a fish in the water, where you see it is not where it is,
and countless people who have decided they'd like to eat fish and
want to spear them, have learned to throw the spear where
the fish doesn't appear to be so they can have it for lunch.
The chick can't do that.
Explore our Catalog
Join for free and get personalized recommendations, updates and offers.
Coursera provides universal access to the world’s best education,
partnering with top universities and organizations to offer courses online.
© 2018 Coursera Inc. All rights reserved.
