Programming Life Histories : Creating Individual Differences By The Experimental Control Of Early Experiences

Area of Science:

• Behavioral Science
• Developmental Psychology
• Animal Behavior

Background:

• Individual differences in behavior are often attributed to genetic factors.
• Understanding the role of early life experiences is crucial for developmental studies.

Purpose of the Study:

• To investigate the impact of early life environmental manipulations on behavioral differences in rats.
• To determine if stable individual differences can be experimentally induced through environmental factors.

Main Methods:

• A 2x2x2x2 factorial design was used to expose rats to 16 unique early life experience patterns.
• Variables included maternal type, infant handling, and pre/postweaning environments.
• Twenty-three behavioral tests were administered, followed by intercorrelation and factor analysis of group mean scores.

Main Results:

• Six behavioral factors were extracted from the data.
• Three factors were clearly identified: emotional reactivity, consumption-elimination, and field exploration.
• Significant and stable individual differences in behavior emerged based on early life experiences.

Conclusions:

• Early life experiences are powerful determinants of stable, complex individual differences in behavior.
• Environmental manipulation can generate behavioral variations previously assumed to be primarily genetic.
• This research highlights the profound impact of environment on behavioral development.