- Inside the
Brain - Problems and
Issues - The
Emergence of Mind - A Musical
Interlude - The
Emergence of Transcendence - Dangers
and Opportunities
How the Neurosciences Explain Religion or
Not
In the last lecture1,
we learned how humans evolved as hunter-gatherers and how our
genetic, mental, and behavioral nature was conditioned by and for
this kind of life, even as we now live in a very different
environment of our techno-cultural creation. We considered
how evolution had shaped our predispositions for religion and
what functions and dysfunctions religion might have played in our
species’ history. We were introduced to the idea that
the human mind was modular, that there were instinctive
dispositions that then developed in conjunction with social
and environmental factors into various inference systems
in our brains. Religion, we were told, could be understood
as a potent combination of these different inference systems in
our evolved brains – agency detection, ontological
categories, intuitive physics, intuitive psychology,
pollution-contagion templates, memory-recall patterns, and so
forth, all assembled and accessed as independent mental modules
(Boyer 2001).
In this lecture, we are going to examine the human brain
directly to see how the cognitive neurosciences try to understand
and explain religious and spiritual experiences. And we
note first that there has been a tremendous amount of new
research and new insights into the working of the human brain in
the last few decades. Powerful new tools also allow us to
examine the function of healthy human brains and these tools have
recently been used to study the brain functions of Buddhist
monks, Catholic nuns, Pentecostals speaking in tongues, and
others.
Inside the
Brain
Now if you look inside the human brain, you do not
actually see these mental modules previously referred to.
There is no piece of the brain that one could label the "agency
detection module" or the "pollution-contagion module". In
dissecting a human cadaver, we first see large-scale
structures. On the outside is the cerebral cortex, or
neocortex, including areas labeled the Frontal Lobe, the Parietal
Lobe, the Occipital Lobe, and the Temporal Lobe, and of course,
these are divided into two hemispheres, right and left, with a
broad band of nerve fibers know as the Corpus Callosum connecting
the two halves. If we peal away the neocortex, we discover
the mesocortex and subcortical structures in the limbic system,
including the Thalamus, the Amygdala, the Hippocampus, and the
Cerebellum, all connected to the brain stem and the spinal
cord. This much you probably already know. Images of
the human brain have become iconic in our 21st century
culture.
A lot of what we know about the specialized functions of
different areas of the brain comes from observing survivors of
traumatic brain injuries or stroke victims. In both cases
neuroscientists correlate the destruction of certain brain
regions due to hemorrhaging or injury with the loss of particular
mental functions, for instance the loss of motor–control, speech,
or even particular parts of speech or sets of word concepts,
the latter known as Aphasia.
Curiously, memory seems to be distributed throughout the
brain and is not located in any particular region. I recall
a colleague at Oxford University, who I visited in the hospital
shortly after he had had a stroke. He could point to Paris
or London on a map, but he could not say the word "Paris" or
"London". Nor could he speak the names of any number
of other common items and places, though he certainly knew what
they were and could directly point to any of them. When I
said "wallet," he reach into his back pocket, pull out the
wallet, he just could not himself say the word "wallet".
Our brains are strange, indeed, though we take them for granted
until something goes wrong. Fortunately, my friend was able
to fully recover his speech, but did so by training new regions
of the brain to compensate for the loss of the one region
destroyed by the stroke. This is an example of another
curious characteristic of the brain called
neuro-plasticity.
When we examine brains under powerful microscopes we see
that the brain is made up of neurons, lots and lots of
neurons. There are different types of neurons in the brain,
and throughout our central nervous system in the rest of the
body, but they all share a basic structure. The cell body
contains the nucleus and organelle. Extending out from the
cell body are lots of dendrite "trees" and axon
"arms". These connect to other neurons. This
maze of connections end in synapses, linking each neurons with
hundreds or thousands of other neurons. The neurons fire
electrical charges in the form of chemical ions, which are
mediated by a variety of neurochemicals that are produced
endogenously by the brain. The chemicals produced and
present in different areas of the brain are very
important.
There are a lot of neurons in the human brain, estimated
at 1011 (one hundred billion). Now each neuron has on
average about 7*103 (seven thousand) synaptic
connections. A three-year old child has about
1016 synapses (10 quadrillion), but this happily
decreases with age to a more manageable number between
1015 to 5*1015 synapses (1 to 5
quadrillion).
Here are a few comparisons to help you remember these
big numbers. The number of neurons in your brain is
approximately the same as the number of stars in our Milky Way
galaxy, which turns out to be conveniently also the number of
galaxies in the observable universe, i.e., one hundred
billion. Or if you prefer, there are more neurons in your
brain than the number of hamburgers served by McDonalds
(before they stopped counting).
And it takes a lot of hamburgers, or other food, to keep
our neurons firing. The 1.5 kilograms of your brain, give
or take, represents only 2 percent of your body weight and yet it
consumes 15 percent of your cardiac output, 20 percent of your
body oxygen, and about 25 percent of your body’s glucose
consumption. Just sitting around the brain needs about 0.1
calories per minute. With intellectual activity this can
increase to as high as 1.5 calories per minute. From a
biophysical and evolutionary point of view, the human brain is an
expensive item. In birth, it is difficult to pass through
the female pelvis, too often resulting in the death of the infant
or the mother. In life, it requires a lot of extra food and
care.
The brain is best understood as a kind of Rube Goldberg
machine. Rube Goldberg (1883-1970) was an American
cartoonist who was famous for depicting complex devices that
performed simple tasks in convoluted ways. One such cartoon
depicts a man eating his soup. The spoon is attached to a string
which flips a cracker to a Parrot which then activates water
pouring into bucket which pulls a string which activates a
lighter which launches a rocket attached to a knife which cuts a
string that turns on a clock with a pendulum which swings back
and forth moving a napkin that now wipes clean the soup-eating
man’s mustache. The entire contraption is worn on the
head of the mustached man as a kind of hat. Our brains are
like this Rube Goldberg machine, except that the complex machine
is worn inside our heads instead of outside.
Neuroscientists today are developing algorithmic flow charts that
map out neural processes. Something simple like engaging in
meditation sets off an impossibly complex series of actions,
reactions, and feedback loops (Newberg 2006). Thankfully,
we do not need to be the least bit aware of any of these
processes to have wonderfully functional brains allowing us to
mindlessly perform lots of simple and complex mental activities
everyday. It is worth stopping a moment, however, to
reflect that the most complicate object in the known universe is
sitting right here between our ears.
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