A Theory for the Origin of Human Menopause

Area of Science:

• Evolutionary biology
• Human evolution
• Reproductive biology

Background:

• The evolutionary origins of human menopause remain incompletely explained.
• Menopause is clinically defined as 12 consecutive months without menstruation.

Purpose of the Study:

• To propose a synthetic evolutionary theory for the origin of human menopause.
• To integrate genetic, behavioral, life history, and social factors.

Main Methods:

• Reviewing existing hypotheses for menopause origins.
• Synthesizing evidence for behavioral, life history, and social changes in early human populations.
• Developing a multi-level evolutionary explanation.

Main Results:

• Lower Paleolithic populations had short lifespans, similar to chimpanzees.
• Three key changes occurred: restricted reproduction to young women, increased lifespan, and a shift in older women's roles to kin care.
• These changes explain the accumulation of late-onset fertility-diminishing mutations and the expression of reproductive senescence.

Conclusions:

• The proposed synthetic theory integrates multiple factors to explain menopause evolution.
• This theory addresses limitations of previous hypotheses.
• It offers testable predictions for future research on human menopause origins.