BEHAVIOUR
Ethology is the study of behaviour in its natural habitat. It is mostly a
descriptive science.
Behaviour:
Behaviour - What an animal does and how it does it.
To some extent ALL behaviour has a Genetic Basis
In general, behaviour is a response to some environmental stimulus
Innate Behaviours - inherited, instinctive:
A. programmed by genes;
B. highly stereotyped (similar each time in many individuals)
C. Four Categories
1. Kinesis: "change the speed of random movement in response to environmental
stimulus"
2. Taxis: "a directed movement toward or away from a stimulus; positive and
negative taxes
3. Reflex: "movement of a body part in response to stimulus".
4. Fixed Action Pattern (FAP): "stereotyped and often complex series of
movements., responses to a specific stimulus - Releaser"
D. Characteristics of Innate Behaviours - especially FAPs:
1. The behaviour is performed without prior experience
2. There is a stereotypic releaser stimulus
3. breeding crosses produce hybrid behaviours
4. the behaviour is adaptive - signs that natural selection is at work
Learned Behaviour: Five Categories:
A. Imprinting
B. Habituation
C. Conditioning - laboratory setting
1. classical conditioning
2. operant conditioning
D. Trial and Error Learning - nature
E. Insight, reasoning
BEHAVIOUR:
For centuries, humans have made effort to understand their/our essence.
What we think of as ourselves is not kidney, intestine or foot... or nerve cell.
To study behaviour, to study the nervous system...
this is a quest to understand our essence.
The study of behaviour has a long history, linked closely with our "evolving" view of what we are in relationship to
the universe - often closely intertwined with our view of God and religion. But biology and church began to split in the
mid -1800s, as interests shifted from cataloguing biological diversity for the clarification of God's plan to the questioning
of how biological diversity arose. (Kepler had already presented a scientific challenge to church view around 1600,
showing that the earth was not the physical centre of the solar system).
Mid - 1800s,
scientists such as Darwin, suggested that all organisms were inter-related, that different organisms, including humans,
derived/evolved from common ancestors.
Mid - 1800s,
Mendell is credited with introducing the idea of inheritance.
Late - 1800s,
scientists began struggling with the neural basis of behaviour what was the mechanism of walking? was it simple reflex or some internal program?
Ramon y Cajal - histology of the brain: neuron as the fundamental unit
Early - mid 1900s,
several German scientists, especially Konrad Lorenz, Niko Tinbergen, and Karl von Frisch observed animals
behaviour and suggested suggest that behaviour can innate, born with rather than learned. Established a field of Ethology;
describing animal behaviour in nature and tending to focus on behaviours that were most likely inherited rather than
learned.
Mid - 1900s,
Ethology combined with neurobiology: Neuroethology. Efforts to understand the neurocircuitry that was responsible for
behaviour. Tended towards reduction: defining behaviour as co-ordinated movement. Creative use of
oscilloscopes/electronics and histology allowed people to identify and follow neurocircuits. Behavioural studies focused on
repetitive movements: swimming, walking, flying. Focused on simple animals with "simple" nervous systems; mostly a
variety of invertebrates; a few vertebrate systems (lamprey swimming, tadpole swimming, bird song). Comparative
biology: for any given problem there is an ideal animal in which to study it.
Concurrent (in parallel), long history (since 1700s)
of trying to understand learning, memory, cognition. Late - 1900s, neurobiological models emerged to understand how
neurocircuitry can account for learning and memory: Aplysia (sea slug) - Gill withdrawal response (simple associative
learning - habituation, facilitation); rat hippocampus - long term memory - synapses that show associative learning.
Present (Today),
all of these efforts intertwine with computational (computer) and theoretical scientists seeking to understand complex brain
function / cognition. Language, emotion, learning, memory. Consider: Annual Neuroscience Meeting in Washington, DC
this week, 25,000 participants.
INNATE BEHAVIOUR
1) CHARACTERISTICS OF INNATE BEHAVIOUR
a) it is performed in a reasonably complete form the first time, if the animal is of the appropriate age , hormone
level and maturity.
b) it is programmed by the genes
c) there is no learning or past experience needed
d) it is stereotypical for the species (all organisms of the same species perform the same innate behaviour the
same way: there is no individuality)
2) TYPES OF INNATE BEHAVIOUR
a) kineses (plural) kinesis (singular)
A kinesis is a behaviour in which an organism changes the speed of it's random movement in response to an
environmental stimulus. The purpose is (although not a conscious decision on the animal's part) to escape a
hostile environment rapidly. As the animal speeds up its movements, it may blunder into a more favourable
environment, at which point the speed of movement slows down. Some of you are using the pillbugs or
sowbugs in your independent research project for the laboratory portion of this course. The movement of the
pillbug from a dry area to the area with higher humidity is a kinesis. Pillbugs slow down when they reach a
damp environment. This explains why so many are found congregated in damp areas under rotting wood.
b) taxes (plural) taxis (singular)
A taxis consists of movements toward (+ taxis) or away from ( -taxis) a stimulus. Moths have a + phototaxis;
they are attracted to light. In one of the first labs you performed this year, you designed an experiment to
determine if the protistan Euglena preferred the dark or light side of a "U" shaped tube. Euglena have a + taxis
to dim light and a - taxis to extremely bright light which might damage their chlorophyll. The graylag butterfly
has a + taxis to bright light when it is being pursued by a predator. The advantage of this behaviour is to blind
the predator, allowing the moth to escape. Taxes are controlled by simple neural mechanisms and are
commonly observed in simple animals and protists. Do vertebrates exhibit any taxes? Fish are negatively
geotaxic (against gravity). They orient the dorsal surface of their bodies away from the force of gravity. Those
of you investigating the response of the blowfly larvae to or away from certain intensities of light are
investigating a taxis.
c) reflexes
The movement of a body part in response to a stimulus is called a reflex. The action is involuntary and often
protective. The brain does not initiate the movement but will be informed that the movement has occurred. The
protective function is to move a part of the body in such a way that it is not damaged. Let's examine the
patellar reflex which you studied in lab. A reflex hammer strikes the patellar tendon, sending sensory impulses
of overstretching of the tendon to the spinal cord through the dorsal root of a spinal nerve. This spinal nerve
synapses with a motor neuron in the grey matter of the spinal cord. The motor neuron sends a motor nerve
impulse out the ventral root of the spinal nerve to the muscles of the anterior thigh. These muscles contract,
extending the knee joint and relieving the overstretching on the patellar tendon. Some reflexes are somatic
reflexes, resulting in the contraction of skeletal muscle. Others are autonomic reflexes, resulting in the
contraction of smooth muscle or the secretion of a gland.
d) fixed action patterns
The final type of innate behaviour is the fixed action pattern. This is a stereotyped, and possibly complex,
series of movements elicited in response to a very particular stimulus called a sign stimulus or releaser. These
types of complex behavioural responses evolved in animals where learning is just not possible. These types of
animals may have a very short life span with non-overlapping generations, or they must perform a certain
behaviour correctly the very first time it is elicited by the releaser. To fail to perform the behaviour or to
perform it correctly may be extremely costly, being eaten by a predator or missing the only opportunity to mate.
If a behaviour pattern is complex, how can you determine if it is an FAP or really a learned behaviour? Innate
behaviour such as FAPs involve no prior learning. A deprivation experiment can be designed in which an
animal is removed from its natural environment prior to any opportunity to observe this behaviour in others.
The animal is hand-reared in a laboratory environment. If, when the animal is of the appropriate maturity and
hormonal level, or motivation, the entire correct behaviour is exhibited with the proper releaser, the researcher
can conclude that the behaviour is innate. An excellent example is the murderous behaviour of nestling cuckoos
hatching in a host bird's nest.