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Genetic admixture in the late pleistocene
1Department of Anthropology, University of Utah, Salt Lake City, Utah 84112, USA.
American Journal of Physical Anthropology
|May 1, 1996
Summary
The study found that the absence of "divergent" archaic mitochondria in modern human DNA suggests low admixture levels. This supports the replacement hypothesis of human origins, especially with a large effective female population size.
Area of Science:
- Paleogenetics
- Human Evolution
- Population Genetics
Background:
- The replacement hypothesis posits modern humans replaced archaic populations globally.
- Interbreeding could introduce archaic mitochondrial DNA (mtDNA) into the modern gene pool.
- Archaic mtDNA would exhibit significant genetic divergence compared to modern mtDNA.
Purpose of the Study:
- To infer the level of archaic admixture in early modern humans.
- To analyze the implications of the absence of highly divergent archaic mitochondria.
- To test the consistency of genetic data with the replacement hypothesis.
Main Methods:
- Analysis of mitochondrial DNA (mtDNA) divergence patterns.
- Modeling population genetics scenarios based on effective female population size.
- Comparing genetic admixture thresholds with fossil record evidence for regional continuity.
Main Results:
- The absence of divergent archaic mitochondria suggests low admixture levels.
- A large effective female population size (>1.6 million) over 40,000 years implies <0.2% archaic mtDNA.
- High admixture rates (>76%) required for fossil-detectable regional continuity would necessitate a very small effective female population size (<1,777).
Conclusions:
- The genetic data strongly support limited admixture between modern and archaic humans.
- The findings are consistent with the replacement hypothesis over regional continuity.
- The effective size of the female human population has likely been substantial for at least 40,000 years.