PSYCHOLOGY AND LIFE: STUDENT’S MEMORANDUM
CHAPTER 3
The Biological and Evolutionary Bases of Behavior
LEARNING OBJECTIVES
On completion of this chapter, students should be able to
1.
understand how biology contributes to the creation of unique individuals;
2.
appreciate the complex interplay among the brain, behavior, and environment that creates the unique
experience of being human;
3.
explain the nature versus nurture and the heredity versus environment controversies;
4.
understand that the complexities of human behavior and individual differences are best explained by
the multi-determined interplay between nature and nurture, not one versus the other;
5.
offer examples when given the statement, "Genes do not code for destinies; they code for potential.";
6.
explain Darwin's Theory of Natural Selection and its relevance and importance to the field of
psychology;
7.
describe the various methods for exploring the functions of the nervous system;
8.
identify the structures and functions of the central nervous system, the peripheral nervous system, and
the autonomic nervous system;
9.
describe the major structures of the brain, identify their function, and explain the role of
neurotransmitters; and
10. explain the basic functions of endocrine system components.
CHAPTER OUTLINE
I. Heredity and Behavior
A. Nature versus Nurture: Human behavior is causally determined by an extremely complex
interaction between heredity and the environment.
B. Evolution and Natural Selection
1.
Natural selection: fundamental assumption of psychology
a) Charles Darwin published The Origin of the Species in 1859.
b) Survival of the fittest: Only those organisms that can adapt to environmental
changes and demands are most likely to survive.
2.
Genotypes: a specific genetic structure.
3.
Phenotypes: observable characteristics or behaviors.
4.
Genotype and environment interact to yield a particular phenotype.
C. Human Evolution
1.
Human evolution is known primarily for this combination of critical adaptations:
a)
Bipedalism: the ability to walk upright (walking on two feet).
b)
Encephalization: an increase in brain size that resulted in increased
cognitive skills (such as problem solving).
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PSYCHOLOGY AND LIFE: STUDENT’S MEMORANDUM
c)
Language: the basis of cultural evolution, which is the tendency of cultures to
respond adaptively, through learning, to environmental change. This works much
more quickly than genetic evolution.
D. Variation in the Human Genotype
1.
Basic genetics
a)
Mendel's theory that pairs of inherited factors from each parent influenced
the properties of offspring laid the foundations of modern genetics. Modern
genetics is far beyond the focus of Mendel, but his work lead to
investigation into the basic structures of the genetic code.
b) Genes: organized components of DNA that contain the instructions for the
production of proteins.
2.
c)
Genes are found on rod-like structures known as chromosomes. Humans
contain 46 chromosomes, 23 from the mother and 23 from the father.
d)
Estimates of the number of genes in the human genome range from 30,000 to
150,000.
e)
The X and Y chromosomes determine sex. One X comes from the mother,
and either an X or a Y comes from the father. XX = female. XY = male.
Genes and Behavior: the interaction of psychology and genetics
a)
Biology (genotype) is not destiny.
b) Genes only determine the range of effects that the environment can have in
shaping phenotype and behavior.
c)
II.
The person that you become is jointly determined by genes and the
environment, by nature and nurture.
3.
Genome is the full sequence of genes associated with the DNA of a species. In 2000,
a working draft of the human genome was published, but work is ongoing to give full
account of each human chromosome.
4.
Behavior genetics studies the relative genetic influence (heritability), as opposed to the
environment, in determining phenotypic variation (i.e., patterns of behavior).
5.
Sociobiology applies evolutionary theory to explain social systems of humans and other
species.
6.
Evolutionary psychology extends the approach of sociobiologists to apply the principles
of evolution to include other aspects of human behavior, including cognitions.
Biology and Behavior
A. Rene Descartes, in the seventeenth century, argued that humans are animal machines and
that human action is a mechanical response to the environment. He revolutionized the study
of human behavior by suggesting that human physiology could be studied empi rically.
Empirical observation has been the primary means by which psychologists have studied
human behavior in the twentieth century. Today, neuroscience is one of the most rapidly
growing areas of research.
B. Eavesdropping on the brain
1.
Broca's area: the region of the brain that translates thoughts into speech
2.
Brain lesions to understand brain structure—function relationships
a) Phineas Gage
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PSYCHOLOGY AND LIFE: STUDENT’S MEMORANDUM
b) Creating lesions can be helpful (e.g., treating neurological disorders like epilepsy) and help to
more accurately identify brain areas and associated functions. Cannot be done experimentally
on humans for obvious ethical reasons.
3.
Alternatives to physical lesions for human research and assessment:
a)
Walter Hess found that sleep, sexual arousal, anxiety, and terror could be
turned on and off by electrically stimulating specific areas of the brain.
b) rTMS: creates temporary "lesions" with pulses of magnetic stimulation.
c)
Electroencephalogram (EEG) records large, integrated patterns of brain
electrical activity.
d)
Positron-emission tomography (PET) scans construct a dynamic portrait of
the brain by detecting how radioactive (but safe) substances are processed in
the brain during different cognitive and behavioral activities.
e)
Magnetic resonance imaging (MRI) uses pulses of energy to cause atoms to
align with a magnetic field. Special radio receivers then monitor the rate at
which atoms decay from alignment once the energy pulse is complete.
Computers analyze this information to create dynamic models of brain
activity.
C. The nervous system comprises two major divisions:
1.
Central nervous system (CNS): all neurons in the brain and spinal cord
a)
Integrates and coordinates all bodily functions, processes all incoming
neural messages, and sends commands to different parts of the body.
b) Relies on PNS for information from sensory receptors.
2.
The Peripheral Nervous System (PNS): all neurons forming the nerve fibers that
connect the CNS to the body
a)
Provides the CNS with sensory information and relays commands from the
brain to the body's organs and muscles.
b) Composed of two subdivisions
(1) The somatic nervous system (SNS) regulates the actions of
skeletal muscles.
(2) The autonomic nervous system (ANS) sustains basic life
processes and is further divided into two subdivisions:
(i) The sympathetic division governs response to emergencies, (ii) The
parasympathetic division governs routine operation of internal bodily functions.
D. Brain structures and their functions
1.
The brain is the most important component of the CNS and is composed of three
layers: the brain stem, the limbic system, and the cerebrum.
2.
The Brain Stem comprises the following structures:
a)
The medulla, located at the top of the spinal cord, controls breathing, blood
pressure, and the heart.
b) The pons, located directly above the medulla, provides inputs to other
structures of the brain stem and to the cerebellum.
c)
The reticular formation, located between the medulla and pons, arouses the
cerebral cortex to new stimulation and keeps the brain alert even during
sleep.
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PSYCHOLOGY AND LIFE: STUDENT’S MEMORANDUM
d) The thalamus, located above the pons, receives input from the reticular
formation and channels incoming sensory information to the appropriate area
of the cerebral cortex.
e)
3.
The cerebellum, attached to the brain stem at the base of the skull,
coordinates body movements and plays a role in some types of learning.
The limbic system mediates motivated behaviors, emotional states, and memory
processes and is composed of three structures:
a)
The hippocampus plays an important role in the acquisition of explicit
memories (ones you are aware of retrieving.)
b) The amygdala plays a role in emotional control and the formation of
emotional memories, especially those related to threat and danger.
c)
4.
The hypothalamus plays a role in maintaining homeostasis in body weight,
temperature, and the endocrine system.
The cerebrum regulates higher emotional and cognitive functions and is composed of
the following:
a)
The cerebral cortex is the thin outer layer of the cerebrum.
b) The cerebrum is divided into symmetrical halves called cerebral
hemispheres.
c)
The two hemispheres are connected by a thick mass of nerve fibers called
the corpus callosum, which relays messages between hemispheres.
d)
Grooves in the cerebrum, called the central sulcus and the lateral fissure,
help divide each cerebral hemisphere into four lobes.
e)
The frontal lobe, located at the front of the cerebrum, is involved in motor
control and cognitive activities (e.g., planning and goal setting).
f)
The parietal lobe is located at the top of the cerebrum and is responsible for
the sensations of touch, pain, and temperature.
g)
The occipital lobe is located at the back of the cerebrum and is responsible
for visual processing.
h)
The temporal lobe is located at the side of the cerebrum and is responsible for
auditory processing.
i)
The hemispheres and lobes of the brain do not function independently, rather they
work as an integrated unit similar to an orchestra.
j)
The motor cortex, located in front of the central sulcus, controls movement of the
body's voluntary muscles.
k) The somatosensory cortex, located behind the central sulcus in the parietal lobes,
processes information about temperature, touch, body position, and pain.
1)
The auditory cortex, in the temporal lobes, processes auditory information, m) The
visual cortex, in the occipital lobes, processes visual information.
n)
5.
The association cortex includes all unlabeled parts of the cortex. It
interprets and integrates information from many parts of the brain.
"Hemispheric lateralization" describes how separate hemispheres are responsible for
some specific functions.
a)
Roger Sperry and Michael Gazzaniga devised situations that could allow visual
information to be presented separately to each hemisphere.
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PSYCHOLOGY AND LIFE: STUDENT’S MEMORANDUM
b) Information from the right visual field goes to the left hemisphere, and
information from the left visual field goes to the right hemisphere.
E.
c)
Speech may be the most highly lateralized of all brain functions. For most
people, speech is a left hemisphere function.
d)
The left hemisphere tends to be more analytical, processing information bit
by bit.
e)
The right hemisphere tends to be more holistic, processing information in
global patterns.
f)
There may be gender differences in lateralization. When making judgments,
the left hemispheres of males showed more activity, while both hemispheres
of females showed activity
The endocrine system is a highly complex communication system comprised of a network of glands that
supplements the work of the nervous system.
1.
Hormones, "the messengers of life," are chemicals secreted by the glands of the
endocrine system. They influence sexual development, physical growth, moods,
arousal level, immune functioning, and metabolism rate.
2.
The hypothalamus serves as an intermediary between the endocrine system and the
nervous system. Messages from the brain cause the hypothalamus to release hormones
to the pituitary gland.
3.
The pituitary gland, the "master gland," secretes about ten types of hormones which
influence the functioning of all other endocrine system glands, as well as growth.
a)
In males, the pituitary gland activates secretion of testosterone, which leads
to sperm production.
b) In females, the pituitary gland activates secretion of estrogen, which is
essential to the release of eggs from the ovaries.
III. The Nervous System in Action
A.
3.
A neuron is a cell specialized to receive, process, and transmit information to other cells. There are at
least 200 different types of neurons, which are typically comprised of dendrites, soma, axon, and
terminal buttons.
1.
Dendrites are branched fibers that extend outward from the body of the neuron and that
receive messages from other neurons.
2.
The soma, or cell body, integrates information received by the dendrites and passes it
along to the axon.
3.
The axon is a single extended fiber that conducts information to terminal buttons.
4.
Terminal buttons are bulblike structures that secrete neurotransmitters, which influence
other neurons.
There are three major classes of neurons: sensory, motor, and interneurons.
1.
Sensory neurons carry messages from sense receptors toward the CNS.
2.
Motor neurons carry messages from the CNS to the muscles and glands.
3.
Interneurons carry messages between different neurons.
4.
Glia cells, derived from the Greek word for "glue," outnumber neurons in the brain by
about five or ten to one and perform three primary functions: housekeeping, insulation,
and protection of the brain.
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PSYCHOLOGY AND LIFE: STUDENT’S MEMORANDUM
a)
Development: glia cells help guide newborn neurons to appropriate
locations in the brain.
b) Housekeeping: glia cells clean up after neurons die and absorb excess
neurotransmitters.
4.
5.
F.
c)
Insulation: glia cells form a myelin sheath around the axon of some types of
neurons, greatly increasing the conduction speed of the axon.
d)
Protection: glia cells form a blood—brain barrier that prevents toxins from
reaching the brain.
Neurons' action potentials: Neurons send messages in an all-or-none fashion through action
potentials traveling down the axon, and they receive messages in the form of graded
potentials through the dendrites.
1.
Excitatory input increases the likelihood that a neuron will fire.
2.
Inhibitory input decreases the likelihood that a neuron will fire.
3.
Graded Potentials are generated by excitatory inputs and vary in size based on
stimulation magnitude. One graded potential is often not enough for a neuron to fire.
4.
Temporal Summation involves several excitatory or inhibitory inputs from the same
source over time.
5.
Spatial Summation involves several excitatory or inhibitory inputs from different
sources at the same time.
The biochemical basis of action potentials
1.
An action potential begins when excitatory inputs are strong enough to overcome
inhibitory inputs and involves depolarization of the neuron by sodium ions rushing into
the cell
2.
Resting potential is the slightly negative voltage of a neuron in a resting state
3.
Ion channels in neuron membranes respond to changes in excitatory and inhibitory
input. Excitatory input causes the ion channels to allow sodium ions into the neuron,
allowing the neuron to fire. Inhibitory input causes the ion channels to keep the neuro n
negatively charged, preventing the neuron from firing.
4.
The action potential then travels down the axon as adjacent areas of the axon
successively depolarize.
5.
When the fluid inside the neuron becomes positive, the sodium ion channels close and
potassium ion channels open, allowing potassium ions to exit the cell, restoring
negative charge of the neuron.
6.
Action potentials obey the "all-or-none law." The size of the action potential is not
influenced by the intensity of stimulation beyond the threshold level.
7.
After firing, neurons enter a refractory period, a period during which they cannot fire or
will only fire with more intense stimulation dm normal.
Synaptic transmission: neural impulses between neurons involves the movement of
neurotransmitters across the synaptic cleft.
1.
A synapse is a small physical gap between neurons.
2.
Once an action potential reaches an axon terminal button, synaptic vesicles release
neurotransmitters into the synaptic gap chemical substances that stimulate other
neurons. The neurotransmitters then traverse across the synaptic gap and attach to
receptor molecules embedded in the postsynaptic neuron membrane.
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G. Neurotransmitters: at least sixty substances are suspected to function as neurotransmitters in the
brain
1.
Acetylcholine, a neurotransmitter found in both the central and peripheral nervous
systems, is implicated in memory loss associated with Alzheimer's disease and in
some types of respiratory failure.
2.
Gamma-amino butyric acid (GABA) is thought to be related to anxiety, as depressants
bind to receptor molecules sensitive to GABA and cause sedation.
3.
Catecholamines such as dopamine and norepinephrine play prominent roles in mood
disturbances and schizophrenia.
a)
Decreased levels of norepinephrine have been related to depression.
b) Increased levels of dopamine have been related to schizophrenia.
4.
Serotonin is involved in autonomic processes, arousal, and depression.
5.
Endorphins are neuromodulators that modify the activities of postsynaptic neurons
and may play an important role in emotional behaviors.
DISCUSSION QUESTIONS
1.
A fundamental, yet often overlooked, assumption of this chapter is that Darwin's theory of natural
selection accurately explains how humans reached our current stage of development. Indeed, it has
become so well accepted that few students will stop to wonder how this chapter would be different if
it were incorrect. But what if it was wrong? What other possible explanations could be put forward
to explain how we are and how we got this way? Such questions lie at the heart of religion,
psychology, and what it means to be human. A little more than one hundred years ago, Lamark's
theory of acquired characteristics was relatively well accepted. Five hundred years ago, asking such
questions was blasphemous. How may we look at human evolution, creation, or development
differently 100 years in the future?
2.
A second important question relating to natural selection is whether humans continue to evolve.
Fewer and fewer genes are being removed from the gene pool as environmental threats are identified
and eliminated. Because fewer individuals succumb to environmental threats, most humans are able
to survive to reproductive maturity and perpetuate their genes. What does this successful elimination
of environmental threats portend for the long-term survivability of our species?
3.
After natural selection, what comes after environmental threats are eliminated and everyone
reproduces? What forces will shape the development of humans in the absence of environmental
threats? Social Darwinism? Cultural evolution? Technological forces? Eugenics?
4.
To what extent can individuals be held accountable for their biology? Should people with a genetic
predisposition to obesity be justified in suing fast food companies because of th eir health effects
relative to their risks? Should an individual with a tumor that causes extraordinarily high levels of
testosterone to be released receive the same sentence for a violent crime as someone without such a
tumor? What if the tumor caused a mental disorder such as schizophrenia? Could the insanity
defense be used?
5.
Parents want what is best for their children. They often go to such lengths as choosing homes near
good schools and sending their children to all sorts of musical, athletic, and academic lessons. What
if the need for all of these expensive lessons would be eliminated if the parents chose their children's
genes wisely before the children were born? What if your parents had selected your genes so that you
were better looking, smarter, more athletic, or more artistically inclined? Would such decisions be
ethical? Would you want to make them for your children? Would you have wanted your parents to
make them for you? Why or why not?
6.
With the advent of modern brain imaging and scanning technologies, the way in which "death" is
often determined has also changed. Where as years ago death was determined by the cessation of
breathing and the lack of a pulse, now it is additionally determined by the lack of brain activity. This
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has made the determination of when someone has actually died much more complicated in many cases.
Cases are commonly reported of people who have drowned or have been frozen, who have not breathed for
dozens of minutes and who have had no heartbeat when found, who were revived, and sometimes have
made complete recoveries. On the other hand, there are also tragic cases of people who have been injured
in accidents who are breathing and have a pulse, but are labeled "brain dead." You might discuss what
brain death means and explore both the medical and moral issues related to these situations.
7.
Have students pick at least one task they would normally do with their dominant hand, and have them
do it with the other hand. Writing a short in-class assignment can be fun. But you can brainstorm and
see what ideas they come up with. Ask students to discuss what problems they encountered while
trying to do things with the opposite hand.
SUPPLEMENTAL MATERIAL
Protecting the Brain
Although the bony skull usually does a good protective job, many brains are still injured in auto and motorcycle
accidents, sports, and even at the hands of parents. Failure to wear seat belts, motorcycle or bicycle helmets, or
the right protective sports equipment can result in permanent damage to some of the brain's functioning.
"Many slow-learning and clumsy children with IQs in the 90s," says pediatrician John Caffey, "might have been
intelligent and normally mobile children with IQs of 120, had they not been habitually shaken and whiplashed
during infancy." Overenthusiastic bouncing of a baby before its neck muscles are strong enough to support the head
may result in broken vessels that deprive the brain of blood and thus retard the growth of parts of the brain. Angry
slaps on the head and neck can have similar negative consequences, even for older children.
Drugs that alter brain functions can have permanent effects if taken in excess. Some drugs, like the chemicals in
glue, when inhaled can lead to death or a lifetime of mental retardation. Brai ns, especially young ones, need lots of
oxygen and good nutrition. They are adversely affected by pollutants in the environment, especially when children
chew on flakes of paint that contain lead.
Although children sustain head trauma in various ways, the most common source is from blows to the head by an
adult, followed by falls from bicycles. Sadly, in a fall from a bicycle or motorcycle, the area of the brain most
likely to be traumatized is the frontal lobe, the area of the brain responsible for plannin g, organization, and decisionmaking.
Aphasias; Frontal and Temporal Lobe Injuries
An aphasia, by definition, is difficulty in producing or comprehending speech when that difficulty is not produced
by deafness or a simple motor deficit, but caused by brain damage. Paul Broca first identified this deficit in his
observations of patients who had been injured in the area of the brain known today as the left frontal lobe.
Although Broca was unable to conduct ablations on his patients, at the autopsies fo llowing their deaths, he
repeatedly found an injury to the same area of the brain in those patients who had manifested difficulty in the
production of speech. His work was eventually connected to that of Karl Wernicke, who found a similar area in the
left temporal lobe and observed that trauma to this area resulted in poor comprehension of speech. Taken together,
we now refer to the areas pinpointed by Broca and Wernicke as the "language center" of the brain. Individually, we
refer to these areas as Broca's area and Wernicke's area.
Neuroglial Cells; The Glue of Life
The term glia is derived from the Greek word for glue and is an appropriate name for the cells that surround all
neurons, sealing them together. Glial cells outnumber neurons ten to one, and, t hough tiny in size, make up half of
the bulk of the brain. Unlike neurons, glia do not possess excitable membranes and so cannot transmit information.
Glia can take up, manufacture, and release chemical transmitters, and in so doing may help to
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PSYCHOLOGY AND LIFE: STUDENT’S MEMORANDUM
maintain or regulate synaptic transmission. Another hypothesis is that glia can manufacture and possibly transmit
other kinds of" molecules, such as proteins. The anatomy of some glial cells is striking in this regard, for they seem to
form a conduit between blood vessels and neurons, and may bring nourishment to the neurons. It is thought that these
cells may have important functions during prenatal development and recovery from brain injury. One role of glia is
known definitely: Certain kinds of glia, called by the tongue-twisting name of oligodendroglia, form the myelin
sheath that insulates axons and speeds conduction of the nerve impulse. A counterpart called a schwann cell
performs the same role for the peripheral nerves. The study of glia is difficult because these tiny cells are
inextricably entwined with neurons. As the most numerous type of cell in the brain, their potential importance is
vast, and investigation of their function seems likely to yield exciting results in the near future.
Charles Darwin and Natural Selection: A Taproot of Contemporary
Psychology
Charles Darwin and his theory of natural selection had a greater impact on the development of modern psychology
than anyone else and continue to have a profound effect on all of the natural sci ences. Natural selection is the one
assumption with which most natural scientists agree, although its exact mechanisms may be disputed. Darwin, a
naturalist, published his theory of evolution in a book entitled On the Origin of the Species by Natural Selection in
1859, about twenty years before the birth of experimental psychology.
Darwin's ideas have shaped contemporary psychology in the following ways:
1.
Continuity between animals and humans. This idea was difficult for society to accept, because
humans assumed that they were the crowning glory of creation and not subject to the natural laws as
were members of the animal kingdom. Even those scientists who applauded Darwin's theory had
some difficulty in accepting the idea that evolution applied to humankind.
2.
Individual differences. The various members of a given species may have many characteristics in
common, but there are also differences among those members—individuals—that can determine
whether the "fitness" of their offspring will enable them to compete successfully in the battle for
survival.
3.
The importance of adaptability. Survival depends on the ability of an organism to adapt to the
environment and to changes in that environment. Failure to adapt means extinction. Ninety -nine
percent of all organisms that have ever lived on earth are already extinct.
4.
The importance of the environment. The surrounding environment changes, over time, and "fitness"
means making the various physical and behavioral changes that are appropriate for survival.
5.
Emphasis on change. Before evolutionary theory, the commonly held view was that the earth and its
inhabitants were immutable and static. Darwin's portrayal of nature is dynamic, mutable, and
interacting.
Darwin's ideas influenced many psychologists, including Freud, Watso n, Skinner, and James. The most apparent
legacy from Darwin to Freud's theory was the idea of the continuity of animals and humans. Freud thought humans
were driven by the same instincts that motivate other animals—instincts to survive and reproduce. According to
Freud, people have no inherently higher nature than do animals, and whatever in humans may be higher (sympathy,
altruism, unselfishness) is a product of the processes of repression and reasoning. In Freud's perspective, the
dominant force in the structure of personality is the id (the representation of the instincts for survival and
reproduction), but humans develop other aspects of personality to control these instincts in order to adapt to
communal lifestyles. Communal living is important in terms of adaptive behavior for humans because humans are
rather weak creatures compared to the large predators.
The idea of continuity between animals and humans also influenced the behaviorist theories of Watson and
Skinner. Watson began his career as an animal psychologist believing, as later did Skinner, that the basic principles
of behavior can be discovered by studying the behavior of animals. Though behaviorists do not deny individual
differences in genetic endowment, they do tend to place greater emphasis on environmental determinants of
behavior. Skinner emphasized learning rather than innate factors as being the antecedent of behavior, believing that
through a process of trial and error, organisms learn which behaviors lead to reinforcement (and ensure survival and
reproduction) and which behaviors are futile (and are followed by loss
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PSYCHOLOGY AND LIFE: STUDENT’S MEMORANDUM
or punishment.) Thus, according to behaviorists, learning is our primary tool for adaptation, and it is the
environment that shapes behavior, rather than "mind" or "conscio usness" within the organism.
Behaviorism also emphasizes change. Both Watson and Skinner suggested that a Utopian society could be built by
imposing proper control on environmental conditions. Emphasis on change is one of the hallmarks of our society; we
are convinced that we can be better, thinner, smarter, richer, and happier. Psychologists have been in the forefront in
convincing us that change is possible, though not necessarily easy.
The idea of adaptation to the environment was the central Darwinian t heme in the functionalism of William James
and the originators of the functionalist approach. Human behavior (James used the term "habits") was considered in
terms of how it served the goal of adaptation. Like the behaviorists, the functionalists saw learning as the primary
mechanism for human adaptation and survival.
A precursor of functionalism was the British intellectual giant, Sir Francis Galton. Using Darwin's theory, Galton
developed a keen interest in individual differences and strived to devise way s to measure these differences.
American psychologists eagerly adopted his ideas, with their emphasis on individualism. Psychological testing
developed from this facet of functionalism and continues to be an active area in American psychology. We have
developed psychological tests to measure almost any trait you can imagine.
Ironically, the founder of psychology as a science, Wilhelm Wundt, was not significantly influenced by Darwin's
theory, and when Wundt's branch of psychology, structuralism, migrated to America, it was unable to adapt and
survive.
BIOGRAPHICAL PROFILES
Rene Descartes (1596 - 1650)
Born of wealthy parents in La Haye, France, Descartes was one of the most influential thinkers of the
Renaissance. He contributed to mathematics, philosophy, psychology, and physiology. Descartes, a very private
man, enjoyed solitude and was iconoclastic. While enrolled at a Jesuit school, he convinced the school
authorities to allow him to sleep until 11 A.M., because he did his best thinking while in bed.
Perhaps because of this individualistic nature, Descartes began to doubt all that he had learned in school. This
skepticism soon spread to all areas of his life. Descartes doubted everything. Of one thing, however, Descartes had
no doubt: that he was doubting. This led to his famous conclusion, "cogito, ergo sum." "I think, therefore I am,"
which suggests that all that is certain concerning the human condition is that each of us exists. Descartes also made
significant contributions to physiology. He believed that what distinguished living from nonliving material was
"animal spirits." Animal spirits, according to Descartes, gave humans their ability to move and worked
mechanically, like hydraulics. Although his notion of animal spirits has been shown incorrect, his study of both
animals and humans paved the way for future discoveries. Descartes also addressed the mind-body problem. He
thought that there was a physical body that could be studied scientifically and that there was a mind that was not
physical and that could not be studied scientifically. He believed the mind and body interacted in the pineal gland,
which sits at the center of the base of the brain. His position was thus dualistic and interactionist.
Because of interference by the Catholic Church and increased demands on his time because of his growing fame,
Descartes moved to Sweden in 1650 to tutor Queen Christina. Unfortunately for humanity, Queen Christina insisted
on being tutored at 5 A.M., well before Descartes' 11 A.M. wake-up time. Within six months of his arrival in Sweden,
Descartes contracted pneumonia and died.
Paul Broca (1824 - 1880)
Born in Sainte-Foy-la-Grand, France, Broca was the only son of a physician and followed his father's lead,
becoming professor of surgery and anthropology in Paris in 1861. During an autopsy on a patient who had suffered
from severe speech deficits, Broca discovered a lesion in the left frontal lobe. This discovery was the first evidence
supporting Franz Gall's notion of localization of brain function, a co ncept that is generally viewed as accurate by
current standards.
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Broca was also responsible for developing the early science of craniometry, the measurement of the skull, and the
anthropological study of the prehistoric practice of trephining, in which small holes were made in the skull of
presumably mentally ill individuals in an attempt to allow demons to escape. He was elected to the French senate in
1879, and his radical political views included the recommendation that public high schools open their doors to
females.
Franz Gall (1758 - 1828)
Gall was born in Baden, Germany, but settled in Vienna as a physician. He was a distinguished anatomist,
responsible for much of our early understanding of the nervous system, particularly the distinction between t he
function of the white (myelinated) and gray (nonmyelinated) matter of the brain. Along with his student, Johann
Spurzheim, Gall promoted the science of phrenology, in which a person's character, and emotional and intellectual
dispositions could be inferred from an assessment of the various bumps and contours of the head. Although long
since discredited as legitimate science, phrenology was extremely popular in its day. (Darwin was nearly kept off
the HMS Beagle because of the shape of his nose.) Nearly t hirty phrenological societies were in existence in
England in 1832, and a number of professional periodicals concerning phrenology flourished during the mid-1800s.
Gregor Mendel (1822 - 1884)
Born in Heizendorf, Austria, Mendel's father was a peasant, his mother a gardener. After studying philosophy at the
University of Olmutz, Mendel entered the Augustinian monastery, where many of his teachers also taught science
and philosophy at the gymnasium or Philosophical Institute. Mendel was put in charge of the experimental garden,
where he began the studies that would come to be identified as the founding of the science of genetics. Conducting
impressively systematic and thorough experiments of hybridization of peas, Mendel accumulated evidence
contradicting the current theory that inheritance was a "blending" or combining process.
Mendel's research was first presented at a scientific meeting in 1865, and in published form in 1866, but went
unnoticed. In 1900, however, three separate scientists reported similar findings, despite having been ignorant of
Mendel's work.
Roger Sperry (1913 - 1994)
Sperry obtained his M.A. in psychology at Oberlin College, followed by a Ph.D. in zoology from the University of
Chicago in 1941. He conducted postdoctoral research under Karl Lashley at Harvard and at the Yerkes Primate
Center. His early research challenged the traditional notion that nerves from sense organs attach to brain areas in
nonspecific ways. Later, he and his students advanced the psychological study of split -brain patients by developing
laboratory tasks that allowed for precise assessment of the frequently subtle impairments experienced by recipients
of the radical operation. In 1981, he was awarded the Nobel Prize in physiology, primarily for his pioneering work
during the 1960s on split-brain phenomena. Sperry wrote later about the mind-body relationship and the ethical
implications of modern research on brain physiology and behavior.
SUGGESTIONS FOR FURTHER READINGS
Adelman, G. (Ed.). (1987). Encyclopedia ofNeuroscience (Vols. 1 & 2). Boston: Birkauser. Provides brief essays on a
wide range of topics by leading neuroscientists.
Bloom, F. F., & Lazerson, A. (1988). Brain, Mind, and Behavior (2nd ed.). New York: Freeman. Built around the PBS
eight-part television series, "The Brain." Includes excellent color illustrations.
Carlson, N. R. (1998). Physiology of Behavior (6th ed.). Boston: Allyn and Bacon.
Damasio, A. R. (1994). Descartes' Error. Emotion, Reason, and the Human Brain. New York: Putnam.
Edwards, A. J. (1994). When Memory Fails: Helping the Alzheimer's and Dementia Patient. New York: Plenum
Press. Offers an excellent overview of the disease processes involved in these illnesses and of how to care for both
the patient and the caregiver in easily comprehensible terms.
Gazzaniga, M. S. (1998). The Mind's Past. Berkeley, CA: University of California Press.
Heifer, M. E., & Kempe, R. S. (1997). The Battered Child (5th ed.). Chicago: University of Chicago Press.
Plomin, R., & McClearn, G. E. (Eds.). (1993). Nature - Nurture and Psychology. Hyattsville, MD: APA Press.
Leading environmentalists and geneticists explore the gap between nature and nurture and contend that the
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PSYCHOLOGY AND LIFE: STUDENT’S MEMORANDUM
concept may indeed be linked.
Sacks, O. W. (1985). The Man Who Mistook His Wife for a Hat and Other Clinical Tales. New York: Harper &
Row. Offers fascinating accounts of work with individuals with various neurological and neuropsychological
problems.
Sacks, O. W. (1995). An Anthropologist on Mars: Seven Paradoxical Tales. New York: Knopf.
Sapolsky, R. M. (1994). Why Zebras Don't Get Ulcers: A Guide to Stress, Stress Related Diseases, and
Coping. New York: Freeman.
Sapolsky, R. M. (1997). The Trouble with Testosterone: And Other Essays on the Biology of the Human
Predicament. New York: Scribner.
Springer, S.P. & Duetsch, G. (1997). Left Brain, Right Brain: Perspectives from Cognitive Neuroscience, 5*1 ed.
San Francisco: W.H. Freeman.
CASE STUDY
Five-and-a-half weeks before her twins were due, Christine felt the first sharp pains of labor. He r husband drove her
to the hospital where, for 16 hours, the two of them followed the breathing instructions given to them during their
natural childbirth class. Then a fetal monitor showed that the heartbeat of one of the babies was weakening. Doctors
quickly performed a Cesarean section. Within minutes, 4-pound Nicole and 3-pound 14-ounce Alexis entered the
world.
Immediately after birth, Nicole and Alexis joined half a dozen other babies in the neonatal intensive care unit. For
two-and-a-half weeks, electronic devices monitored their vital signs. Experienced nurses tended to their physical
needs and held them frequently. Christine spent a good part of each day with her babies, holding and rocking them
and feeding them her breast milk from bottles, awaiting the day when she could actually breast feed them. Wearing
diapers barely the size of cocktail napkins, the twins looked fragile and unfinished. With no layers of baby fat, every
little rib showed.
Had Nicole and Alexis been born twenty years earlier, their first few weeks of life would have been quite different.
Until the late 1970s, premature infants were touched as little as possible. Parents and medical personnel feared that
any unnecessary contact with the outside world might harm the babies. Fortunat ely for Nicole and Alexis, we now
know better.
Research with infant rats and humans has led scientists to conclude that brain functioning can be altered by touch, and
that, for newborns, touch is essential for normal growth and development. Biologist Saul Schanberg found that when
rat pups were removed from their mothers, the levels of an enzyme important for growth decreased dramatically.
The longer they were deprived of maternal contact, the less responsive the pups became. The effects of maternal
deprivation could be reversed in only two ways: by returning them to their mother, who immediately started to lick
them, or by having a researcher vigorously stroke them with a small paintbrush. Shanberg concluded that, "the need
for a mother's touch is really brain based. It is not just nice to have it. It's a requirement for the normal development
and growth of the baby."
Psychologist Tiffany Field, who had collaborated with Schanberg, conducted similar stimulation studies of
premature human infants. Her research team randomly selected twenty preemies to receive periodic massages
throughout the day, while twenty others received normal hospital treatment in the intensive care unit, treatment that
did not include massage. According to Field, "The premature babies who were massaged for forty-five minutes a
day for ten days before they were discharged gained 47 percent more weight than the babies who did not get
massaged. They were more active. They were more alert." Eight months later, the massaged babies had maintai ned
their weight advantage and were more advanced in motor, cognitive, and emotional development. This research is
being extended and replicated in larger samples of preemies in order to establish the power of human touch on
biological and psychological health.
In the United States, more than 0.25 million infants are born prematurely each year. Those who are touched and
cuddled leave the hospital several days sooner than usual, reducing care costs by about $3,000 per child.
Unfortunately, not all hospitals apply what scientists have learned about the positive effects of early touch on
development. If they did, the lives of thousands of children would be improved, saving billions of dollars each year—
both practical benefits of this basic research.
When Nicole and Alexis left the hospital, they were still small, but were developing so well that doctors felt
confident they would be all right. At home, the babies shared a crib in the living room, where relatives and friends
who remarked on their tiny size were encouraged to pick up the babies gently and cuddle them. Christine and her
husband were acutely aware of the important role played by human touch in the optimal development of the brain
and the mental and psychical processes that it controls.
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