Chapter 47: Social Interactions
Core Reading: 832-843; Interest Reading 844-849.
Focus Questions:
Explain why "selfish" behaviors do not always result in one passing on more genes/ Explain why altruistic behaviors might be favored in the course of evolution.
Given a behavior (Salix retrieving a duck, for example) classify it as imprinting, classical conditioning, operant conditioning, habituation, spatial learning or insight learning.
Behavior is a fascinating characteristic of certain living organisms. Like any trait, behavior has been shaped by evolution. A behavior should provide an individual with a survival advantage. In this chapter, we will examine how behaviors develop and how certain behaviors can be seen to convey a survive advantage for an individual or a species.
How Behaviors Develop:
Certain behaviors are clearly instinctive, meaning they come naturally to a species without any experimental learning. (Warning: instinct is often applied to behaviors that require some learning, such as a bird’s song, which they inherently begin to sing but they need some ‘coaching’ to get the song correct.) Other behaviors require learning. Many fall in between these two extremes, requiring both genetic influences and learning.
How can a behavior be instinctive? The chapter begins with the example of a snake with an inborn ability to ‘taste’ banana slugs and reject other types of slugs. Clearly, the DNA of the species codes for this behavior as no learning is required. Some behaviors are controlled by the release of hormones (which are coded for by DNA). Hormones are signaling chemicals released within the body that control or coordinate the functions of other cells. In some cases, pheromones (a hormone-like substance released outside the body) are used to control other members of the same population.
Many behaviors are learned. At a basic level, we recognize six types of learning:
1. Imprinting – A response to a sign stimuli (usually occurs early in life) during a critical ‘window’ of time. This case is illustrated by Lorenz’s experiment in which the ducks first saw him as they hatched and then identified Lorenz as their mother.
2. Classical Conditioning – Linking of an involuntary, unconditioned response to a previously meaningless trigger. The famous example would be Pavlov and his dog experiment. Remember: the stimulus precedes the action.
3. Operant Conditioning – The most common type of learning to humans. Operant conditioning links voluntary actions with consequences/stimuli. Remember: action precedes reward.
4. Habituation – Learning that certain stimuli have no effect, thus eliminating a response to such stimuli. The book provides the great example of pigeons in large cities learning that humans are not a threat but rather a potential source of food. Remember: the loss of a natural response.
5. Spatial/Latent Learning – Many animals are able to navigate familiar territory by memorizing landmarks. Bees are great at finding their hives and many birds migrate hundreds or even thousands of miles, in part by using spatial landmarks.
6. Insight Learning – "Higher" learning, associated with problem solving and reasoning. Seen only in some birds and mammals.
Why do certain behaviors persist?
Remember, populations are the functional units of evolution. A behavior persists if it is adaptitive for the population, meaning it increases the chance that the population will thrive. Surprisingly, this doesn't necessarily mean that the behavior is "selfish," serving only the reproductive interests of one individual. Consider your textbook example of honeybees and naked mole rats: both of these species display altrusistic individuals that are actually helping their family gene pool (known as the theory of indirect selection).
Communicating Without Words
Many animals communicate between individuals. How? One of the most common means of communicating is with chemical communication signals known as pheromones. Whether pheromones are active in humans is not debating; rather, the debate is in regards to how influential they are within are species. Of course, other species communicate with song, sounds, dance, colors and appearance, or a combination of these methods.
Benefits of a Social Group
One of the greatest misreadings of science has been the idea that is natural to be selfish, aggressive and disinterested in the welfare of others. There are actually many benefits to forming a cooperative group, including the avoidance of predators (one grouse often sits 'sentinel,' watching for danger signs), cooperation in accomplishing a task (wolf couldn't bring down large game without cooperation), cooperation in raising young, caring for sick and injured (humans, but also elephants and wolves) and accomplishments that couldn't be completed by one individual (a honeybee hive or ant hill, for example).