Download Table of Contents - Milan Area Schools

52
What, How, and Why Questions
• What questions focus on the stimuli that elicit a
behavior; such stimuli are the proximate causes of
the behavior.
• How questions focus on the development of a
behavior and the neural and hormonal mechanisms
that underlie a behavior.
• Why questions are concerned with the function and
evolution of a behavior; the selective pressures that
shape a behavior are considered ultimate causes.
52
Behavior Shaped by Inheritance
• Stereotypic behaviors are performed in the same
way every time. If there is little difference in the
way different individuals perform the behavior it is
said to be species-specific.
• Ex. Web spinning by spiders.
Figure 52.1 Spider Web Designs Are Species-Specific
52
Behavior Shaped by Inheritance
• Ethologists study the behavior of animals in their
natural environments.
• The parallel field of comparative psychology
focuses on learning by animals in laboratory
environments.
• Central Question: To what extent are behaviors
determined by inheritance and to what extent are
they modified by experience.
52
Behavior Shaped by Inheritance
• Deprivation and hybridization experiments were
used to determine whether a behavior is inherited.
• In deprivation experiments, animals were raised
in conditions the behavior being studied.
• If the behavior was displayed in its entirety, then it
was described as inherited.
• Ex. Squirral story.
52
Behavior Shaped by Inheritance
• In hybridization experiments, closely related
species that differ in aspects of a behavior are bred
to produce hybrid offspring.
• Konrad Lorenz did hybridization experiments with
duck species that can interbreed, but rarely do so
because of the specificity of their courtship displays.
• His results showed that motor patterns of courtship
displays are inherited.
52
Behavior Shaped by Inheritance
• Releasers are stimuli that trigger many inherited
behaviors.
• Releasers are usually a simple sensory signal.
 What they see, hear, etc.
• Ex. Herring gulls, bulls.
52
Behavior Shaped by Inheritance
• Today, behavioral biologists believe that most
behaviors develop through an interaction of
inheritance and learning.
• For example, begging in herring gull chicks also
has a learned component: Over time, gull chicks
learn the characteristics of their parents, refine
their parental image, and eventually beg only from
their own parents.
52
Behavior Shaped by Inheritance
• Imprinting is a type of learning in which animals
learn, during a critical period, a complex set of
stimuli that later act as a releaser.
• Lorenz showed that newly hatched goslings
imprint on the image of the first object they see
(normally their parent, but under experimental
conditions, Lorenz or his assistants).
• Subsequent exposure to the object releases the
goslings’ following behavior.
Figure 52.5 Imprinting Enables an Animal to Learn a Complex Releaser
52
Behavior Shaped by Inheritance
• The ability to learn and modify behavior based on
experience can change behaviors often.
• In species with non-overlapping generations,
opportunities to learn from parents are not
available, so inherited behaviors are very
important.
 Spiders and their webs.
52
Behavior Shaped by Inheritance
• Inherited behaviors also occur when there are
opportunities for learning the wrong behavior,
when mistakes would be costly or dangerous.
• The behavior must be performed correctly the
first time; there may be no second chance.
 Ex. Predator avoidance
52
Hormones and Behavior
• Differences in behaviors of males and females are
an example of genetic influence on behavior.
• Action of the sex steroids on the brain determine
sex differences in behavior.
• The sexual behavior of rats differs between males
and females.
• Receptive female rats display lordosis, a posture
in which the hindquarters are slightly raised.
• Male rats, on the other hand, display mounting
and copulatory behavior.
52
Hormones and Behavior
• Sex steroids present early in life determine which
pattern of sexual behavior an adult rat will display.
Figure 52.7 Hormonal Control of Sexual Behavior (Part 1)
Figure 52.7 Hormonal Control of Sexual Behavior (Part 2)
52
The Genetics of Behavior
• Behavior has genetic determinants. Genes code
for proteins; there are then many complex steps
between this starting point and the expression of
a behavior.
• There is no behavior for which we know the
precise series of steps from gene to behavior.
52
Communication
• Communication is behavior that influences the
actions of other individuals.
• The displays or signals of communication
convey information, and the transmission of this
information benefits the sender and the receiver.
• There are five channels of communication:
chemical, visual, auditory, tactile, and electric.
These channels differ in their effectiveness in
different environments.
52
Communication
• Pheromones are molecules used in chemical
communication between individuals.
 Ex. Territory marking, attraction.
• Pheromones remain in the environment for a
while, in contrast to vocal or visual signals.
52
Communication
• The advantages of visual signals include ease of
production, diversity, flexibility, speed, and a clear
indication of the position of the signaler.
• The disadvantages of visual signals include failure
to get the attention of the receiver if they are not
seen.
 Poor light, crowded enviroment.
52
Communication
• Auditory signals can be used at night or low-light
environments. Also the receiver does not have to
be focused on the sender.
• Communicating with sound works well over long
distances.
 Humpback whales, can be heard hundreds of
kilometers away.
• However, visual signals are better than auditory
signals at rapidly conveying complex information.
52
Communication
• Communication by touch is very common among
animals, particularly when conditions are poor for
visual communication.
 Bee story from reading.
What happened here?
Figure 52.12 The Waggle Dance of the Honeybee
52
Communication
• Some fish emit electric pulses and generate
electric fields in the water around them. Such
signals can be used to detect objects in the
environment and to communicate.
52
The Timing of Behavior: Biological Rhythms
• Circadian rhythms are rhythms that are about 24
hours long but do not depend on the cycle of light
and dark.
• Animals in constant darkness demonstrate daily
cycles of sleep and activity; they are said to have an
endogenous (internal) clock.
52
The Timing of Behavior: Biological Rhythms
• Entrainment is the process of resetting the
circadian rhythm by exposure to environmental
cues.
• In mammals, the master circadian clock is located
in the suprachiasmatic nuclei (SCN).
• The SCN is found only in vertebrates; in some
vertebrates, the SCN is the master clock
(mammals), and in others the master clock is the
pineal gland (birds).
52
The Timing of Behavior: Biological Rhythms
• The clock genes that regulate circadian rhythms
are homologous across a wide range of
organisms.
• In fruit flies, the genes period (per) and timeless
(tim) are clock genes.
• In fruit flies mutations cause flies to have short or
long circadian periods or can result in loss of
circadian rhythms.
52
The Timing of Behavior: Biological Rhythms
• Some animals, such as those that hibernate,
cannot rely on day length as a cue of upcoming
seasonal change and instead have endogenous
annual rhythms called circannual rhythms.
52
Finding Their Way: Orientation and Navigation
• Piloting is a simple means of navigation involving
the use of landmarks.
• Gray whales use landmarks along the west coast
of North America to find their way between the
Bering Sea and the coastal lagoons of Mexico.
• Homing is the ability of an animal to return to its
nest site or burrow.
• In many animals, homing involves piloting, the
use of landmarks in a familiar environment.
52
Finding Their Way: Orientation and Navigation
• Animals may use the sun and the stars to
determine direction.
• The sun is an excellent compass, provided the
time of day is known. Animals can determine time
of day from their circadian clocks.
• Clock-shifting experiments have shown that birds
are capable of using their circadian clocks to
determine direction from the position of the sun.
52
Finding Their Way: Orientation and Navigation
• Some birds, such as pigeons, can orient well
under overcast skies, apparently using their ability
to sense Earth’s magnetic field and thus gain
directional information.
• When small magnets were attached to the heads
they could not find their way.
52
Human Behavior
• Culture is the transmission of learned behavior
from one generation to another and is characteristic
of humans.
• Human behavior is also influenced by genetic
factors.
 Blind infants smile and frown although they
have never seen these expressions in others.