What percentage of DNA do humans and chimpanzees share?

One Perspective

Although it has commonly been stated in the past that humans and chimpanzees have 98.5% DNA similarity, this figure has recently been found to be incorrect. Newer research has suggested that there is approximately 96% genetic similarity between Humans and chimpanzees overall.

Of course the fine details depend on what specific chromosomes one is looking at. Although 96% of the DNA is similar overall, there are some very significant differences in some chromosomes, where other chromosomes are nearly identical. Specifically, 18 of the chromosomes of humans are nearly identical to those of chimpanzees, the rest are very different (eg: chromosomes 4, 9, 12, 21, and y).

Some specific examples of differences include:

1) Humans have 23 pairs of chromosomes in total while chimpanzees have 24.

2) Chimpanzees and other apes have telomeres about 23 kilobases long, whereas humans are completely unique among primates with much shorter telomeres only 10 kilobases long.

3) The Y chromosome in chimpanzees is smaller than that of humans and only 60% of the genes are similar to those of the y chromosome of humans.

REFERENCES:

  1. Jennifer F. Hughes et al. 2010. Chimpanzee and human Y chromosomes are remarkably divergent in structure and gene content. Nature. Online first. January
  2. Archidiacono, N. et al. 1998. 'Evolution of chromosome Y in primates.' Chromosoma 107:241-246.
  3. Britten, R.J. 2002. 'Divergence between samples of chimpanzee and human DNA sequences is 5% counting indels.' Proceedings National Academy Science 99:13633-13635.
  4. Fujiyama, A., et al. 2002. 'Construction and analysis of a Human-Chimpanzee Comparative Clone Map.' Science 295:131-134.
  5. Gagneux, P. and Varki, A. 2001. 'Genetic differences between humans and great apes.' Mol Phylogenet Evol 18:2-13.

Another Perspective

It really depends on what we are comparing - the entire genome or just the small fraction (1%) which codes for proteins. If we compare the ENTIRE genome to another then the figures for similarity are very low and in fact, such a study has not been done. If we compare the similarities between the genes that code JUST FOR PROTEINS (1% of entire genome), then the figure is very high! The vast majority of mammalian DNA does NOT code for proteins - it was once believed to be "junk DNA" with no function - Now we know this assumption was totally wrong. We now know they play an important role in preserving the genome itself - and many other functions as well.