1. 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.

2. 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.

3. Figure 52.1 Spider Web Designs Are Species-Specific

4. 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.

5. 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.

6. 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.

7. 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.

8. 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.

9. 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.

10. Figure 52.5 Imprinting Enables an Animal to Learn a Complex Releaser

11. 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.

12. 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

13. 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.

14. 52 Hormones and Behavior Sex steroids present early in life determine which pattern of sexual behavior an adult rat will display.

15. Figure 52.7 Hormonal Control of Sexual Behavior (Part 1)

16. Figure 52.7 Hormonal Control of Sexual Behavior (Part 2)

17. 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.

18. 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.

19. 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.

20. 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.

21. 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.

22. 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?

23. Figure 52.12 The Waggle Dance of the Honeybee

24. 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.

25. 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.

26. 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).

27. 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.

28. 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.

29. 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.

30. 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.

31. 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.

32. 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.