Genomic Evidence of Archaic Human Interbreeding

evidence

1. Non-African Ancestry:

2. Shared Derived Alleles:

3. Chromosomal "Deserts":

4. Ancient Hybrid Individuals:

5. Adaptive Introgression:

1. Non-African Ancestry:

   Modern non-Africans

1. carry 1–4% Neanderthal DNA,

1. Non-African Ancestry:

   1. Melanesians/Oceanians

1. have 2–6% Denisovan DNA, absent in most Africans.

1. Shared Derived Alleles:

• Matching of Neanderthal/Denisovan-specific SNPs in modern human genomes (e.g., EPAS1 in Tibetans from Denisovans).

chromosomal "Deserts":

• Large regions of modern human genomes (especially X chromosome) lack Neanderthal DNA, suggesting hybrid incompatibility.

1. Ancient Hybrid Individuals:

• Direct evidence from fossils (e.g., Denisova 11, a first-generation Neanderthal-Denisovan hybrid).

1. Adaptive Introgression:

• Archaic alleles retained in modern populations confer advantages (e.g., EPAS1 for high-altitude adaptation, HLA immune genes).

Key Methods:

• Comparison of ancient genomes (e.g., Altai Neanderthal) to modern human variation.

  • Identification of haplotype blocks with divergent ancestry.

Limitation:

No Neanderthal mtDNA/Y chromosomes survive in modern humans,

suggesting selection against archaic male lineages.