Microevolutionary hypothesis of the obesity epidemic

Area of Science:

• Human evolution
• Epidemiology
• Genetics

Background:

• The global obesity epidemic is a significant human phenotypic change.
• Obesity is highly heritable, but a rapid gene pool change is not typically considered its cause.
• Modern obstetrics dramatically altered evolutionary pressures related to obesity.

Purpose of the Study:

• To test the microevolutionary hypothesis of the obesity epidemic.
• To investigate the link between reduced childbirth mortality and rising obesity rates.
• To determine if changes in the human gene pool, influenced by obstetrics, contribute to the obesity epidemic.

Main Methods:

• Regression analysis of data from approximately 190 countries.
• Examined associations between 1990 lifetime maternal death rates (LMDR) and current obesity rates.
• Multivariate regression and partial correlation analyses controlling for GDP, calorie intake, and physical inactivity.

Main Results:

• LMDR correlated more strongly with national obesity rates than GDP, calorie intake, or physical inactivity.
• LMDR explained approximately 11% of the variability in obesity rates between nations.
• In nations with high LMDR, this metric explained 33% of obesity variance, independent of other factors.

Conclusions:

• The microevolutionary hypothesis provides a parsimonious explanation for the global obesity epidemic.
• Reduced maternal mortality due to modern obstetrics has potentially lifted a negative selection pressure against obesity.
• Evolutionary changes in the human gene pool may be a significant driver of the current obesity crisis.