Killer Cell Ig-Like Receptor (KIR)

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Human Uniqueness Compared to "Great Apes": 
Likely Difference

The human KIR family encodes lymphocyte receptor for human leukocyte class I antigens. This family is unique in human in that it is separated into two haplotype groups (A and B), defined by centromeric and telomeric motifs. Each haplotype group arose after the Pan-Homo split, with the haplotype-distuinguishing telomeric motifs arising more recently than the centromeric motifs.


Timing of appearance of the difference in the Hominin Lineage as a defined date or a lineage separation event. The point in time associated with lineage separation events may change in the future as the scientific community agrees upon better time estimates. Lineage separation events are defined in 2017 as:

  • the Last Common Ancestor (LCA) of humans and old world monkeys was 25,000 - 30,000 thousand (25 - 30 million) years ago
  • the Last Common Ancestor (LCA) of humans and chimpanzees was 6,000 - 8,000 thousand (6 - 8 million) years ago
  • the emergence of the genus Homo was 2,000 thousand (2 million) years ago
  • the Last Common Ancestor (LCA) of humans and neanderthals was 500 thousand years ago
  • the common ancestor of modern humans was 100 - 300 thousand years ago

Possible Appearance: 
6,000 thousand years ago
Probable Appearance: 
1,700 thousand years ago
The Human Difference: 

Novel haplotypes

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Referenced By:


  1. Different patterns of evolution in the centromeric and telomeric regions of group A and B haplotypes of the human killer cell Ig-like receptor locus., Pyo, Chul-Woo, Guethlein Lisbeth A., Vu Quyen, Wang Ruihan, Abi-Rached Laurent, Norman Paul J., Marsh Steven G. E., Miller Jeffrey S., Parham Peter, and Geraghty Daniel E. , PLoS One, 2010, Volume 5, Issue 12, p.e15115, (2010)