Lecture Notes: Nature vs. Nurture and Epigenetics

Introduction to Lucky Lyle and Trouble Tim

• Identical Twins: Lyle and Tim are identical twins raised in different environments.
• Different Outcomes: Lyle is a model citizen, while Tim turns to crime.
• Question: How can identical twins have such different life outcomes?

Early Theories of Human Development

• Supernatural Explanations: Initial explanations of human behavior included supernatural elements.
• Emergence of Science: Science gradually gained credibility in explaining human behavior.
• Social Science Theory (Nurture): Environment shapes who we are.
• Biological Science Theory (Nature): Genes predetermine our traits from birth.

The Battle of Nature vs. Nurture

• Two Competing Theories: Nature (genes) vs. Nurture (environment).
• Emergence of a New Field: Epigenetics: A field studying the interaction between genes and environment.

Epigenetics and Michael Meaney's Research

• Research Question: What makes a good rat mother?
• Experiment Setup:
  • Two groups of rats: high-licking mothers vs. low-licking mothers.
  • Licking behavior is associated with motherly care.
• Results:
  • High-licking mothers produce high-licking offspring.
  • Fostered babies adopt the licking behavior of their foster mothers.

Genetic and Epigenetic Observations

• Methyl Groups: Molecules attached to genes that can silence them.
• Findings:
  • High-licking mothers' offspring have fewer methyl groups.
  • Low-licking mothers' offspring retain more methyl groups.
  • Adopted rats mimic the methylation pattern of foster mothers.

Implications for Humans

• Environmental Influence: The environment and lifestyle choices affect genetic expression in humans.
• Observable Changes: Changes can be observed at the DNA level.
• Positive Outlook: Epigenetic changes occur throughout life, allowing for personal development and change.

Conclusion

• Summary: Genes provide a blueprint, but environmental factors and lifestyle choices influence outcomes through epigenetic mechanisms.
• Takeaway: Our choices and environments have a profound impact on our biological development.