Summary: Chapter 8 - Hormones And Social Behavior

Read the summary and the most important questions on Chapter 8 - Hormones and Social Behavior

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• What is social behavior?

  Social behavior includes interactions between individuals from which one or more of the individuals benefit. Includes aggression, as well as non-hostile interactions like affiliation, courtship and parental behaviors.

• What are the costs of living in a group?

  1. Increased ease of disease transmission
  2. Increased competition for resources (food, mates, nesting sites)
  3. Increased conspicuousness for predators

• What are the benefits of living in a group?

  1. Antipredator detection, defense and dilution
  2. Elevated foraging efficiency
  3. Group defense of resources
  4. Increased mating opportunities

• How are social behaviors that keep animals apart referred to?

  Aggression or territorial behaviors.

• What is the effect of sex steroid hormones on social interactions?

  • High circulating sex steroid hormones tend to be associated with low tolerance of close proximity of same sex conspecifics, whereas low circulating sex steroid hormones permits social tolerance and prosocial interactions.
    
  • Estrogen treatment of short-day female meadow voles prevents formation of social bonds. However, ovariectomy of long-day meadow voles does not promote formation of social bonds.

• What type of hormones are important in affiliative behavior

  Hormones that are also important in reproductive and parental behaviors.

• What is the difference between monogamous and polygamous species regarding testosterone and the testes? How can this be explained?

  • Males of polygamous species have more testosterone, more sperm and larger testes than monogamous species. 
    
  • Explained by the fact that it is critical for the reproductive success of monogamous species to form long-term pair bonds.
    

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• Explain the difference in oxytocin receptor locations in the brains of monogamous and polygamous voles.

  • Monogamous prairie voles: Oxytocin receptor densities were highest in prelimbic cortex, nucleus accumbens, and the lateral aspects of the amygdala. 
  • Polygamous montane voles: Oxytocin receptors were not evident in these brain areas.

• What is the difference in vasopressin receptors in the brain between monogamous and polygamous voles?

  Monogamous voles have higher numbers of the 1a type of vasporessin receptor in the ventral pallidum, medial amygdala, and mediodorsal thalamus than polygamous voles.

• What is the difference in response of monogamous and polygamous vole pups to separation from their family?

  • Monogamous (prairie voles): Isolated from their family at 4-6 days old for 5 minutes --> 300 distress calls. At 8-10 days old --> 600 distress calls. Elevation of plasma corticosterone x6.
  • Polygamous (montane voles): Isolation from their families did not result in distress calls and no change in corticosterone levels.