Humans and chimpanzees share about 96 percent of their DNA sequence identity when considering the entire genome, including insertions and deletions. Without accounting for these insertions and deletions (large mismatched sections), the DNA sequence that can be directly compared between the two species is almost 99 percent identical. This means that on a letter-by-letter DNA sequence comparison, excluding big mismatches, humans and chimps are 98.7% to 99% similar, but including all DNA parts, the overall similarity is closer to 96%.
More recent analyses suggest that the total difference in DNA between humans and chimps may be larger than the commonly cited 1%, with estimates reaching around 14-15% difference when including gaps in the genome that are unalignable or missing between species. This challenges the simplistic 99% similarity figure but does not negate the close evolutionary relationship.
In summary, the traditionally cited figure is that humans and chimpanzees share approximately 96-99% of their DNA, depending on how the comparison is made, with some newer research suggesting a more nuanced and slightly larger difference overall. This high degree of similarity underlines that chimpanzees are our closest living relatives.
