The Development and Structure of Animal Behavior

Genes and Behavior

A number of lines of evidence show the clear effect of genes on behavior. However, it is important to know that genes do not code for behavior directly.

  1. Inbreeding experiment involve mating members of closely related (inbred) lines. As they interact with the same environment, any behavioral differences are considered to be genetically based. One experimental technique is the use of avoidance learning.
  2. Genetic influences can be demonstrated by artificial selection&emdash;that is, managed breeding for specific behavioral traits.
  3. In hybridization experiments, individuals of closely related strains, but with differing specific behaviors, are bred. If the resulting behaviors are of one parental type or the other, a few genes are believed to be involved. If resulting behavior is a blend of parental types, many genes are believed responsible
  4. Studies of identical twins separated at birth (especially in humans) has led to a better understanding of the roles of genetics verses environment on the influence of behavior.


Hormones and Behavior

Hormones can influence behavior, and the effect can be studied in two ways: by gland removal and hormone replacement or by correlational analysis.

The Three Ways Hormones Can Influence Behavior are by:

  1. Altering perception (ability to detect and understand stimuli - software)


  2. Development of the nervous system (hard wiring - morphology, physiological activity, and the role of neurotransmitters)


  3. Altering Effector Mechanisms (peripherals to the nervous system, such as muscle strength, secondary sexual development, etc.

The Ethologist's Concept of Instinct

The concept of instinct was developed by ethologists (Lorenz et. al.) Ethology is the study of animal behavior in natural settings (in the wild). Animal behavior [involves] causation, development, evolution, [&] function.

INSTINCT - innate behavior usually manifesting itself in response to some stimulus

Three concepts are central to instinct.
  1. Sign stimuli are specific environmental signals that release instinctive behaviors. (cause)


  2. Innate releasing mechanisms are neural centers that are activated by the perception of sign stimuli (perception and control)


  3. Fixed action patterns are genetically based behaviors that are performed at a signal from (2) the nervous system. They are performed independently of environmental influences.

LEARNING - Learning is a process of developing a behavioral response based on experience.

Reinforcement is the result of an action that increases the probability of the action's being repeated.

Kinds of learning
  1. Habituation is learning not to respond to stimulus (an irrelevant stimulus).


  2. Classical conditioning involves a behavior that is normally released by one stimulus coming to be released by another stimulus.


  3. Operant conditioning involves an animal learning to perform an act in order to receive a reward.


  4. Latent learning occurs in the absence of an immediate reward. learning occurs, although the reward is delayed.


  5. Insight learning involves solving problems without resorting to trial and error. The trials take place mentally.


  6. Imprinting is a kind of learning that takes place only in a brief period of an animal's early life.

How Instinct and Learning Can Interact 

Most behaviors are based on interactions between instinct (genetically based) and learning (experience-based). The degree to which experience can alter innate patterns depends largely on the species and the specific behavior in question. Most innate patterns can be improved upon by experience. some of the most intriguing studies of the instinct-learning interaction are on song learning in the white-crowned sparrow.


Memory is the storage and retrieval of information.

Theories on Information Storage include:

  1. Two separate mechanisms are involved: long-term memory and short-term memory.
  2. Information in long-term memory is slower to decay (forget) and harder to disrupt.
  3. Short-term memory must precede long-term memory.
  4. The consolidation hypothesis states that an effect of experience enters a short-term system. Then one forgets, unless the effect is shifted to long-term memory.


Physiological Differences in Long- and Short-Term Memory


Short-term memory does not form engrams and may operate over reverberating neural circuits. Long-term memory does form engrams.