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The evolution of human populations: a molecular perspective
1Department of Ecology and Evolutionary Biology, University of California, Irvine 92717, USA.
Molecular Phylogenetics and Evolution
|February 1, 1996
Summary
Human evolution involved large populations, not narrow bottlenecks, according to MHC gene data. Molecular evidence supports a recent African origin for modern humans spreading globally.
Area of Science:
- Evolutionary biology
- Human origins
- Population genetics
Background:
- Speciation theories, like founder-event speciation, suggest population bottlenecks drive rapid morphological change.
- The Major Histocompatibility Complex (MHC) is highly polymorphic, offering insights into population history.
- Previous theories proposed significant population bottlenecks in human evolution.
Purpose of the Study:
- To investigate the role of population bottlenecks in human evolution using MHC gene data.
- To estimate the effective population size of early humans.
- To reconcile molecular data with speciation theories.
Main Methods:
- Gene coalescence theory applied to 19 human DQB1 alleles.
- Computer simulations to model polymorphism decay rates.
- Analysis of mitochondrial DNA (mtDNA), Y-chromosome, and microsatellite polymorphisms.
Main Results:
- Human DQB1 alleles suggest a large, stable population size (approx. 100,000) over millions of years.
- Computer simulations indicate bottlenecks involved thousands, not a few individuals.
- MHC data aligns with mtDNA, Y-chromosome, and microsatellite findings, refuting narrow bottlenecks.
Conclusions:
- Human evolution did not involve severe population bottlenecks.
- Large, stable ancestral populations maintained genetic diversity.
- Molecular data supports a recent African origin and subsequent dispersal of modern humans.