Lesson Overview 29.1 Elements of Behavior

THINK ABOUT IT At a Caribbean seaside restaurant, a young boy eats a hamburger, unaware that he’s being watched—by an iguana. This lizard, a shy tree-dwelling species, is a vegetarian. He makes a beeline for the boy’s french fries. These iguanas normally don’t approach humans, but this particular iguana has learned that getting close to humans can mean easy access to food.

Behavior and Evolution What is the significance of behavior in the evolution of animal species?

Behavior and Evolution What is the significance of behavior in the evolution of animal species?   If a behavior that is influenced by genes increases an individual’s fitness, that behavior will tend to spread through a population. Over many generations, various kinds of adaptive behaviors can play central roles in the survival of populations and species.

Behavior and Evolution Behavior is the way an organism reacts to stimuli in its environment.   Usually, behaviors are performed when an animal detects and responds to some sort of stimulus in its environment. The way an animal responds to a stimulus, however, often depends on its internal condition. Many behaviors are essential to survival. To survive and reproduce, animals must be able to find and catch food, select habitats, avoid predators, and find mates. Behaviors that make these activities possible are just as important as physical characteristics.

Behavior and Evolution Some behaviors are influenced by genes and can therefore be inherited.   If a behavior that is influenced by genes increases an individual’s fitness, that behavior will tend to spread through a population. Over many generations, various kinds of adaptive behaviors can play central roles in the survival of populations and species.

Behavior and Evolution The genes that code for the behavior of the moth helps it escape predators.

Behavior and Evolution If disturbed, the moth will move its front wings to expose a striking circular pattern on its hind wings. This behavior may scare off predators that mistake the moth’s hind-wing pattern for the eyes of a predator.

Innate Behavior What is an innate behavior?

Innate Behavior What is an innate behavior?   Innate behaviors appear in fully functional form the first time they are performed, even though the animal has had no previous experience with the stimuli to which it responds.

Innate Behavior Innate behaviors are also called instincts.   The suckling of a newborn mammal is an example of an innate behavior. All innate behaviors depend on patterns of nervous system activity that develop through complex interactions between genes and the environment. Innate behaviors enable animals to perform certain tasks essential to survival without the need for experience.

Learned Behavior What are the major types of learning?

Learned Behavior What are the major types of learning?   The four major types of learning are habituation, classical conditioning, operant conditioning, and insight learning.

Learned Behavior Acquiring changes in behavior during an animal’s lifetime is called learning.   Many animals have the ability to learn. This chimpanzee is exhibiting a complex learned behavior—using a tool to “fish” for termites.

Habituation Habituation, the simplest type of learning, is a process by which an animal decreases or stops its response to a repetitive stimulus that neither rewards nor harms the animal. Often, learning to ignore a stimulus that offers neither a reward nor a threat can enable an individual to spend its time and energy more efficiently.

Habituation Birds on the side of a road take flight when a car approaches (left). After the passage of many cars, which haven’t harmed them, the birds no longer take flight when one approaches (right). The birds have become habituated to the stimulus of passing cars.

Classical Conditioning Classical conditioning is a type of learning in which a certain stimulus comes to produce a particular response, usually through association with a positive or negative experience.

Operant Conditioning Operant conditioning occurs when an animal learns to behave in a certain way, through repeated practice, to receive a reward or avoid punishment.   Operant conditioning is sometimes described as a form of trial-and-error learning. Trial-and-error learning begins with a random behavior that is rewarded in an event called a trial.

Operant Conditioning A dog randomly brushes its tail against a bell hanging on a doorknob.

Operant Conditioning The owner responds by opening the door to let the dog outside.

Operant Conditioning After the “ring the bell; open the door” sequence has occurred several times, the dog has learned to ring the bell when it wants to go out. The dog has learned by operant conditioning how to be let out of the house.

Insight Learning The most complicated form of learning is insight learning, or reasoning. Insight learning occurs when an animal applies something it has already learned to a new situation, without a period of trial and error.   Insight learning is common among humans and some other primates.

Complex Behaviors How do many complex behaviors arise?

Complex Behaviors How do many complex behaviors arise?   Many complex behaviors combine innate behavior with learning.

Complex Behaviors Some animals recognize and follow the first moving object that they see in their early lives. This process is called imprinting and it involves both innate and learned behavior.

Complex Behaviors Young birds have an innate urge to follow the first moving object they see. But they are not born knowing what that object will look like, so they must learn from experience what to follow. These baby sandhill cranes have imprinted on their mother and will follow her in flight.

Complex Behaviors Once imprinting has occurred, the behavior becomes fixed. Sometimes, the fixed object of imprinting shows up later in life. Animals can imprint on sounds, odors, or any other sensory cues. Sometimes, animals imprint on objects.

Complex Behaviors For example, in an experiment, recently hatched cranes raised in captivity imprinted on a hand puppet. Later, that puppet is used to help introduce these birds to the wild by guiding them along a migration route that they would normally learn by following their parents.