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In human genetic studies, the CHLCA is useful as an anchor point for calculating single-nucleotide polymorphism (SNP) rates in human populations where chimpanzees are used as an outgroup, that is, as the extant species most genetically similar to Homo sapiens. Despite extensive research, no direct fossil evidence of the CHLCA has been discovered.
For example, neutral human DNA sequences are approximately 1.2% divergent (based on substitutions) from those of their nearest genetic relative, the chimpanzee, 1.6% from gorillas, and 6.6% from baboons. [10] [11] Genetic sequence evidence thus allows inference and quantification of genetic relatedness between humans and other apes.
Common descent is a concept in evolutionary biology applicable when one species is the ancestor of two or more species later in time. According to modern evolutionary biology, all living beings could be descendants of a unique ancestor commonly referred to as the last universal common ancestor (LUCA) of all life on Earth.
The time to the genealogical MRCA (most recent common ancestor by any line of descent) of all living humans cannot be traced genetically because the DNA of the great majority of ancestors is completely lost after a few hundred years. It is therefore computed based on non-genetic, mathematical models and computer simulations.
Human accelerated regions are areas of the genome that differ between humans and chimpanzees to a greater extent than can be explained by genetic drift over the time since the two species shared a common ancestor. These regions show signs of being subject to natural selection, leading to the evolution of distinctly human traits.
[citation needed] However, more recent studies have modified the commonality of 98 percent to a commonality of 94 percent, showing that the genetic gap between humans and chimps is larger than originally thought. [3] Such information is useful in searching for common ancestors and coming to a better understanding of how humans evolved.
The term sister group is used in phylogenetic analysis, however, only groups identified in the analysis are labeled as "sister groups".. An example is birds, whose commonly cited living sister group is the crocodiles, but that is true only when discussing extant organisms; [3] [4] when other, extinct groups are considered, the relationship between birds and crocodiles appears distant.
The identical ancestors point for Homo sapiens has been the subject of debate. In 2003 Rohde estimated it to be between 5000 and 15,000 years ago. [2] In 2004, Rohde, Olson and Chang showed through simulations that, given the false assumption of random mate choice without geographic barriers, the Identical Ancestors Point for all humans would be surprisingly recent, on the order of 5,000 ...