chromosomes appear to have split at different times, suggesting that large-scale hybridization may have taken place over a period of as much as four million years leading up to the emergence of the distinct human and chimpanzee lineages as late as six million years ago. The similarity of the X chromosome in humans and chimpanzees might suggest hybridization taking place as late as four million years ago. However, other mechanisms such as natural selection on the X chromosome in the chimpanzee–human last common ancestor may also explain the apparent short divergence time in the X chromosome. Humanzees in fiction "Chromosome 6" (1998) by Robin Cook "Facts Concerning the Late Arthur Jermyn and His Family" by H. P. Lovecraft First Born by the BBC Les orchidées de Staline (2017) by Corinne De Vailly and Normand Lester, Next (2006) by Michael Crichton, Sims by F. Paul Wilson "Williamson" (1946) by Henry S. Whitehead See also Great ape personhood Human–animal hybrid Human evolution References Human hybrids Human subject research Chimpanzees Intergeneric hybrids