Understanding variation in human fertility: what can we learn from evolutionary demography?

Area of Science:

• Evolutionary demography
• Human fertility studies

Background:

• Human fertility has significantly declined globally over the past two centuries.
• Understanding the reasons for fertility variation between and within populations remains a complex challenge.
• Fertility is influenced by both physiological and behavioral factors, necessitating an interdisciplinary approach.

Purpose of the Study:

• To summarize the historical development of evolutionary demographic research on human fertility.
• To describe the current state of the field, including recent theoretical and empirical advances.
• To propose future research directions for understanding fertility variation.

Main Methods:

• Review of historical evolutionary demographic research on human fertility.
• Analysis of theoretical frameworks, particularly fitness maximization.
• Examination of empirical studies from high-fertility and small-scale societies.
• Inclusion of contemporary research on cultural and psychological mechanisms.

Main Results:

• Early evolutionary demography advanced understanding of fertility variation through a fitness maximization lens.
• Research initially focused on high-fertility populations and subsistence societies.
• Hypotheses were developed to explain fertility decline during the demographic transition.
• Current research increasingly incorporates cultural, psychological, and multi-causal factors.

Conclusions:

• Evolutionary demography has evolved from a focus on fitness maximization to a more nuanced understanding of fertility.
• The field is expanding to address fertility in complex modern and transitioning societies.
• Future research should continue to integrate diverse mechanisms and societal contexts to fully understand human fertility.