Genetics and behaviour ERQ (Suderman and Weaver)

INTRODUCTION - GENETICS AND BEHAVIOUR (EPIGENETICS)

Genetic influences on behaviour are not solely determined by inherited DNA sequences, but also by epigenetic mechanisms that regulate gene expression. Epigenetics explains how environmental factors such as parenting or trauma can switch genes on or off without altering the DNA sequence. This essay will discuss epigenetic influences on behaviour using Weaver et al. (2004) and Suderman et al. (2014).

Definition - Epigenetics

Epigenetics refers to changes in gene expression caused by environmental factors without altering the underlying DNA sequence.

Definition - DNA Methylation

DNA methylation is an epigenetic process where chemical markers attach to DNA and reduce or silence gene expression.

Definition - Gene-Environment Interaction

This refers to how environmental factors influence the expression of genetic predispositions.

WEAVER ET AL. (2004) - AIM

To investigate how maternal behaviour in rats influences epigenetic changes in offspring.

WEAVER ET AL. (2004) - PARTICIPANTS

Laboratory rats raised in controlled conditions.

WEAVER ET AL. (2004) - PROCEDURE

Rat pups were raised by either high nurturing mothers (high LG-ABN) or low nurturing mothers. Researchers measured DNA methylation levels and later cross-fostered pups between mothers to test environmental influence.

WEAVER ET AL. (2004) - RESULTS

Pups raised by nurturing mothers showed different DNA methylation patterns and reduced stress responses. These changes persisted into adulthood and were reversible when pups were cross-fostered.

WEAVER ET AL. (2004) - CONCLUSION

Early environmental experiences (maternal care) can alter gene expression through epigenetic mechanisms, affecting behaviour such as stress response.

WEAVER ET AL. (2004) - STRENGTHS

Controlled lab conditions increase reliability and allow replication. Demonstrates clear gene-environment interaction. Longitudinal measurement shows lasting effects of epigenetic changes.

WEAVER ET AL. (2004) - LIMITATIONS

Animal study limits generalisability to humans. Low ecological validity due to artificial lab conditions. Other variables may influence methylation, reducing internal validity.

SUDERMAN ET AL. (2014) - AIM

To investigate whether childhood abuse is associated with epigenetic changes in adulthood.

SUDERMAN ET AL. (2014) - PARTICIPANTS

40 adult males (12 with history of childhood abuse, 28 controls), aged around 45.

SUDERMAN ET AL. (2014) - PROCEDURE

Blood samples were analysed to measure DNA methylation levels, particularly in the PM20D1 gene, and compared between abused and non-abused individuals.

SUDERMAN ET AL. (2014) - RESULTS

Participants with childhood abuse showed increased DNA methylation, particularly in the PM20D1 gene. This was associated with long-term outcomes such as higher rates of obesity.

SUDERMAN ET AL. (2014) - CONCLUSION

Traumatic environmental experiences can lead to long-term epigenetic changes that influence behaviour and health outcomes.

SUDERMAN ET AL. (2014) - STRENGTHS

Provides real-world human evidence for epigenetics. Links environmental trauma to biological changes and behaviour. High ecological validity due to naturalistic variables.

SUDERMAN ET AL. (2014) - LIMITATIONS

Correlational study cannot establish causation. Small sample size reduces generalisability, restricted to males only, may be different in females. Potential confounding variables (lifestyle, genetics) not fully controlled.

HOLISTIC DISCUSSION - Gene expression is dynamic, not fixed

Epigenetics challenges deterministic views of genetics by showing that genes can be switched on or off depending on environmental experiences, making behaviour more flexible and adaptable.

HOLISTIC DISCUSSION - Importance of early life experiences

Weaver et al. demonstrates that early environmental factors such as maternal care can have long-lasting effects on gene expression and behaviour, highlighting critical periods in development.

HOLISTIC DISCUSSION - Long-term impact of trauma

Suderman et al. shows that adverse experiences like childhood abuse can lead to persistent epigenetic changes, influencing behaviour and health decades later.

HOLISTIC DISCUSSION - Nature and nurture interaction

Both studies support an interactionist approach, showing that behaviour is shaped by the interaction between genetic predispositions and environmental influences rather than either alone.

HOLISTIC DISCUSSION - Reversibility of epigenetic changes

Weaver et al. suggests that epigenetic modifications can be reversed through environmental changes, offering implications for interventions and therapy.

HOLISTIC DISCUSSION - Methodological differences

Weaver et al. provides controlled experimental evidence but lacks human applicability, while Suderman et al. provides real-world human data but lacks experimental control. Together, they provide complementary evidence.

HOLISTIC DISCUSSION - Reductionism of biological explanation

Focusing on epigenetics may oversimplify behaviour by reducing it to biological mechanisms, ignoring cognitive and social influences.

HOLISTIC DISCUSSION - Ethical and practical implications

Research into epigenetics highlights the importance of improving early environments and reducing trauma, as these factors can have long-term biological and behavioural consequences.

HOLISTIC DISCUSSION - Determinism vs plasticity

Epigenetics balances biological determinism with environmental plasticity, suggesting behaviour is influenced by biology but can still change based on experiences.

HOLISTIC DISCUSSION - Overall evaluation

Epigenetic research provides strong evidence for gene-environment interaction and helps explain individual differences in behaviour, but it should be integrated with cognitive and sociocultural explanations for a complete understanding.