Chapter 2 Flashcards
W
e all tend to think about things in ways that
have been ingrained in us by our
Zeitgeist (pronounced ZYTE-gyste ), the general intellectual
climate of our culture. That is why this is a particularly important chapter for you. You see, you are the intellectual
product of a Zeitgeist that promotes ways of thinking
about the biological bases of behavior that are inconsistent
with the facts. The primary purpose of this chapter is to
help you bring your thinking about the biology of behavior in line with modern biopsychological science
The tendency to think about behavior in terms of dichotomies is illustrated by two kinds of questions that
people commonly ask about behavior: (1) Is it physiological, or is it psychological? or
(2) Is it inherited, or is it
learned? Both questions have proved to be misguided; yet
they are among the most common kinds of questions
asked in biopsychology classrooms.
Cartesian dualism,
, as Descartes s philosophy became
known, was sanctioned by the Roman Church, and so the
idea that the human brain and the mind are separate entities became even more widely accepted. It has survived
to this day, despite the intervening centuries of scientific
progress. Most people now understand that human behavior has a physiological basis, but many still cling to the
dualistic assumption that there is a category of human activity that somehow transcends the human brain
Is It Inherited, or Is It Learned?
The tendency to think in terms of dichotomies extends to
the way people think about the development of behavioral capacities. For centuries, scholars have debated
whether humans and other
animals inherit their behavioral capacities or acquire them through learning. This debate is commonly referred to as the nature nurture issue
At the same time that experimental psychology was
taking root in North America, ethology (the study of animal behavior in the wild) was becoming the dominant
approach to the study of behavior in Europe. European
ethology,
in contrast to North American experimental
psychology, focused on the study of instinctive behaviors
(behaviors that occur in all like members of a species, even when there seems to have been no opportunity for
them to have been learned), and it emphasized the role of
nature, or inherited factors, in behavioral development
The first case is Oliver Sacks s (1985) account of the
man who fell out of bed. This patient was suffering from
asomatognosia, a deficiency in the awareness of parts of
one s own body. Asomatognosia typically involves the left
side of the body and usually results from damage to the
right parietal lobe
A Model of the Biology of Behavior So far in this
section, you have learned why people
tend to think about the biology of behavior in terms of dichotomies, and
you have learned some of the reasons why this way of
thinking is inappropriate. Now, let s look at the way of
thinking about the biology of behavior that has been
adopted by many biopsychologists (see Kimble, 1989). It
is illustrated in Figure 2.3. Like other powerful ideas, it
is simple and logical. This model boils down to the single premise that all behavior is the product of interactions among three factors: (1) the organism s genetic
endowment, which is a product of its evolution;
(2) its
experience; and (3) its perception of the current situation.
Darwin presented three kinds of evidence to support
his assertion that species evolve: (1) He documented
the evolution of fossil records through progressively
more recent geological layers. (2) and (3)?
(2) He described striking
structural similarities among living species (e.g., a
human s hand, a bird s wing, and a cat s paw), which
suggested that they had evolved from common ancestors. (3) He pointed to the major changes that had been brought
about in domestic plants and animals by programs of
selective breeding. However, the most convincing evidence of evolution comes from direct observations of
rapid evolution in progress (see Orr, 2009). For example, Grant (1991) observed evolution of the finches of the
Galápagos Islands a population studied by Darwin
himself after only a single season of drought.
Now, let s look at the way of
thinking about the biology of behavior that has been
adopted by many biopsychologists. Like other powerful ideas, it
is simple and logical. This model boils down to the single premise that all behavior is the product of interactions among three factors: (1) the organism s genetic
endowment, which is a product of its evolution;
(2) its
experience; and (3) its perception of the current situation.
Darwin was not the first to suggest that species
evolve
The development of each individual s nervous system depends on its interactions with its environment (i.e., on its experience). 4 Each individual s genes initiate a unique program of neural development. 3 Experience modifies the expression of an individual s genetic program. 2 Evolution influences the pool of behavior-influencing genes available to the members of each species. 1
The success of each individual s behavior influences the likelihood that its genes will be passed on to future generations. 7 Each individual s current behavior arises out of interactions among its ongoing patterns of neural activity and its perception of the current situation 6 Each individual s current behavioral capacities and tendencies are determined by its unique patterns of neural activity, some of which are experienced as thoughts, feelings, memories, etc. 5
______, in the
Darwinian sense, is the ability of an organism to survive and contribute its genes to
the next generation.
Fitness
Why is social dominance an important
factor in evolution?
One reason is that in some species dominant males copulate more than nondominant males and thus are more effective in passing on their characteristics to future generations.
The males of many species establish a stable hierarchy of _____ ______ through combative encounters with other males. In some species,
these encounters often involve physical damage; in others, they involve mainly posturing and threatening until one of the two combatants
backs down. The dominant male usually
wins encounters with all other males of
the group; the number 2 male usually
wins encounters with all males except the
dominant male; and so on down the line.
Once a hierarchy is established, hostilities
diminish because the low-ranking males
learn to avoid or quickly submit to the
dominant males.
social dominance
An intricate series of _____ _____ precedes copulation in many species. The male approaches the female and signals his interest. His signal
(which may be olfactory, visual, auditory, or tactual) may elicit a signal in the female, which may elicit another re
sponse in the male, and so on until copulation ensues.
courtship displays
A ______ is a
group of organisms that is reproductively isolated from
other organisms; that is, the members of a species can
produce fertile offspring only by mating with members
of the same species
species
______ are
animals with dorsal nerve cords (large nerves that run along
the center of the back, or dorsum); they are 1 of the 20 or so
large categories, or phyla (pronounced FY-la ), into which
zoologists group animal species.
Chordates (pronounced KOR-dates ) The spinal bones are called
vertebrae (pronounced VERT-eh-bray ), and the chordates
that possess them are called vertebrates.
The advantages of life on land were so great that natural selection transformed the fins and gills of bony fishes to legs
and lungs, respectively and so it was that the first
_______ evolved about 400 million years ago.
amphibians
About ___ million years ago,
reptiles (e.g., lizards, snakes, and turtles) evolved from a
branch of amphibians. Reptiles were the first vertebrates to
lay shell-covered eggs and to be covered by dry scales.
300 million
About ___ million years ago,
during the height of the age of dinosaurs, a new class of
vertebrates evolved from one line of small reptiles. The females of this new class fed their young with secretions
from special glands called mammary glands, and the
members of the class are called mammals after these
glands.
180 million
Primates of the family that
includes humans are the ______. According to the simplest view, this family is composed of two genera (the plural of genus): Australopithecus and Homo. Homo is thought
to be composed of two species: Homo erectus, which is extinct, and Homo sapiens (humans), which is not.
hominins
The first Homo species are thought to have evolved
from one species of Australopithecus about _ million years
ago
2 million
Not all existing adaptive characteristics evolved to
perform their current function. Some characteristics,
called _______, evolved to perform one function
and were later co-opted to perform another. For example, bird wings are exaptations they are limbs
that first evolved for the purpose of walking.
exaptations
Similarities among species do not necessarily mean that
the species have common evolutionary origins. Structures that are similar because they have a common evolutionary origin are termed _______;
homologous
structures
that are similar but do not have a common evolutionary origin are termed _______.
analogous
The similarities between analogous structures result from ______ _______, the evolution in unrelated species of similar
solutions to the same environmental demands.
convergent
evolution
A more reasonable approach to the study of brain
evolution has been to compare the evolution of different
brain regions (Finlay & Darlington, 1995; Killacky,
1995). For example, it has been informative to consider
the evolution of the ____ _____ separately from the evolution of the _______
brain stem, cerebrum
In general, the brain stem regulates reflex activities that are
critical for survival (e.g.,
heart rate, respiration, and
blood glucose level)
whereas the cerebrum is involved in
more complex adaptive processes such as
learning, perception, and motivation.
