Biological Basis of Behavior  Biological Rhythms  Neural Centers (Brains)  Hormones Control Animal Behaviors

Biological Basis of Behavior  Biological Rhythms –Circadian rhythms  24 hours of chemical activity – controls sleep and wakefulness  The same gene controlling our 24 hour “clock” is found in animals ranging from fruit flies to hamsters to humans

Migration and Circadian Rhythms  Animals migrating long distances use the position of the sun AND the time of day (circadian rhythm) to know where they are.  It is a built-in GPS device!

Studies on Circadian Rhythms with Humans  Experiments –Subjects = blind individuals and sighted individuals –In a light controlled environment, both groups displayed cycles very close to 24 hours.

Studies on Circadian Rhythms with Humans  Surveys and Experiments –Early morning people and late morning people – have different levels of chemical activity during the day.

Circadian Rhythms and You -Decide by yourself if you are an early morning, late morning or an evening person. -Take a survey and find out for sure!

Circadian rhythms  Example of Circadian rhythms in –House Mouse – Aggressive behavior vs. Parental behavior Mouse

House Mouse  Natural conditions –Male copulates with female –After copulation the male becomes highly aggressive to mouse pups—killing any he finds. What is the evolutionary cause of this behavior? (In other words—what makes this behavior an adaptation— something that improves survival?)

House Mouse  Natural conditions –Aggressive behavior lasts 21 days –Between 3 -7 weeks the male is protective of all mouse pups he comes across. –At 7 weeks the male copulates again and the cycle restarts. What is the evolutionary cause of this behavior?

House Mouse  Lab study –Scientists shift mouse “clock” by changing length of light/dark exposure.  Mice exposed to 22 hour cycles of light/dark (short days) OR  Mice exposed to 27 hour cycles of light/dark (long days)

House Mouse  Lab study –“Short day” mice are exposed to pups on the 20 th REAL day (but their 22 nd day). Consider: How should a male mouse behave towards pups on the 20 th day after copulation? How should a male mouse behave towards pups on the 22 th day after copulation?

House Mouse  The results: –Males were tricked into “thinking” that it was 22 days after copulation. –Males were NOT aggressive to mouse pups!!

House Mouse  Lab study –“Long day” mice are exposed to pups on the 22 nd REAL day (but their 19 th day). –Males show aggression to pups! What happens? How do the male mice act towards the pups?

Circannual rhythms  One year cycle of chemical activity –Examples: time to  Feed  Hibernate  Reproduce  Etc.  In most cases, these behaviors are environmentally independent.

Circannual rhythms  Example of Circannual rhythms in –Golden Mantled Ground Squirrel and hibernation Ground Squirrel Ground Squirrel

Golden Mantled Ground Squirrel  Lab Study –Squirrels blinded at birth –Environmental conditions kept the same throughout the year: same temperature, same amount of food

Golden Mantled Ground Squirrel  The squirrels entered hibernation at the SAME TIME as its species in the wild under changing environmental conditions!

Circannual Rhythms Read Turtle Article and Answer Questions

Neural Command Centers a.k.a. Brains  A brain is the part of the nervous system that controls and coordinates the mental and physical actions of an animal  Vertebrates and invertebrates have brains.  The only animal without a nervous system at all is the sponge.

Invertebrate Brain  Simple animal brains –Small worms—a group of neurons (nerve cells) acting together = brain  If an earthworm is touched, the stimulus is detected by receptor cells in the skin  The receptor cells send a message via nerve cells to the brain, where the information is interpreted. –Octopus –most complex invertebrate brain Read Article: Octopus Arms Found to Have “Minds” of Their Own

The Vertebrate Brain  Name the 5 groups of Vertebrates: ________________,________________, ________________, ________________, ________________,  The brain is located at the anterior (= on or in the front end of the body) of the spinal cord Mammals AmphibiansBirds ReptilesFish

Brain  Parts –Cerebrum – controls voluntary or conscious activities of the body –Cerebellum – coordinates the movement of the body –Medulla oblongata – controls the functioning of many internal organs that do not involve any conscious control (breathing and heart rate)

How the Brain Works  Listen to Sebastian Seung, professor of computational neuroscience at MIT on National Public Radio, February 17, 2012* February 17, 2012February 17, 2012  Read the Interview Highlights with Professor Seung

Fish and Amphibians Brain  The anterior end of most brains contains olfactory bulbs (smell) which is well developed

Reptile Brain  Similar to amphibian/fish brain. Cerebrum and cerebellum are larger when compared to the rest of the brain

Bird Brain  Cerebrum—responsible for nest-building, care of young, courtship and mating—is large.  Cerebellum—responsible for controlling the coordinated movements of flight—is large

Mammal Brain  Most highly developed brain of all animals. –Contains: cerebrum, cerebellum, medulla oblongata AND –Cerebral cortex: outer layer of cerebrum— center for thinking and other complex behaviors

Hormonal Systems  Hormone — A chemical substance produced in the body that controls and regulates the activity of certain cells or organs.  All vertebrates have hormones  Testosterone – usually associated with aggressiveness and sexual readiness in males

Hormones  1771 – England: Scientist transplanted a rooster’s (male chicken) testes (where testosterone is produced) into a hen (female chicken) and found she grew rooster-like combs and wattles.

Hormones In 1849, a scientist transplanted testes from a normal rooster into a castrated rooster. The castrated rooster regained his combs and wattles, his crowing voice, and his fighting behavior.In 1849, a scientist transplanted testes from a normal rooster into a castrated rooster. The castrated rooster regained his combs and wattles, his crowing voice, and his fighting behavior.

Hormones  Estrogen – Usually associated with female reproduction and parental behavior  Often hormones act together with circannual rhythms –The level of testosterone in male mice increases after mating and stays high for three weeks. The testosterone level drops on the 22 nd day after mating and remains low for 4 weeks.

Hormones and Lizards  Sexual behavior of an Anole –Anoles spend the winter under a rock –January – males emerge and establish breeding territories –May –females emerge and begin to lay one egg every days for 3 months (6-9 eggs)

Experiment  Question: How do the levels of hormones correlate with this activity?  Studies have found the levels of testosterone in males is VERY HIGH in early spring and then levels decrease.  Studies have found the levels of estrogen in females is VERY HIGH in early spring and then levels decrease.

Experiment  Question – What causes this change to happen?  In lab: Females exposed to spring-like conditions (it was actually winter). They increased their estrogen levels and produced eggs.  This proved that hormone levels increased based on __________ _____________ environmental conditions

Experiment  The experiment was repeated. Females divided into: –Group A -- exposed to males –Group B -- exposed to only females  Group A produced eggs more quickly than Group B  Conclusion: Hormone production is increased by two types of stimulation– springlike conditions + presence of males!

Biological Basis of Behavior  Biological Rhythms  Neural Centers (Brains)  Hormones Control Animal Behaviors