Biomedical Engineering Reference
In-Depth Information
Biologists state that human evolution has only been possible due to
a combination of personal survival and reproduction. To enhance these
two, man has evolved as a group animal. Living in a group diminishes
external dangers and gives better opportunities for raising children. So
survival, reproduction, and group behavior are key elements in our
existence, and our brain is developed in such a way that it can ensure
these three basic functions. When we zoom in on personal survival, we
can see that we survive due to a combination of physical integrity and
good nutrition. Safety behavior guarantees that the body stays in good
shape. Managing serious risks is a natural and essential element.
To gain a deeper understanding of our present safety behavior, we
can divide evolution into five stages. We will now tour through each of
these stages, starting 300 million years ago and ending today. The
most relevant items of our genetic blueprint will be discussed.
2.1 STAGE 1, FROM 300 MILLION TO 200 MILLION YEARS
AGO
—
THE DEVELOPMENT OF THE BASIC BRAIN
The first stage of the tour starts roughly 300 million years ago, the
period in which the first reptiles
—
—
developed.
The reptiles already had a brain system with basic functions we can still
distinguish today in the human brain. One part of our present brain still
has a strong resemblance with the brains of reptiles. This part is called
the
like lizards and snakes
The basic brain
takes care of all our basic functions for survival: being awake, sleeping,
breathing, eating and drinking, sex, and basic coping behaviors like
fighting, fleeing, or freezing. All our sensory information passes for a
first stop in this basic part of the brain. During this first stop, all the
information is quickly processed and subjected to a first scan. This scan
is on a nonconscious level and focuses on the three basic missions in life:
survival, reproduction, and cooperation. A safety check is one of the
important elements of survival and part of the first stage of all our per-
ception. The sensed information is then sent to other areas of the brain,
where the conscious seeing, hearing, smelling, and touching is done.
A direct result of the nonconscious prescanning can be that the attention
of the eyes and the ears is focused on particular stimuli. This focusing is
done to collect more and better information. So we can focus our eyes
on the floor just to check for a potential risk (for example, something
that might be a snake), on the behavior of others (for example, to see
“
basic brain,
”
or sometimes even the
“
reptile brain.
”
