The genome of our closest living relative – the chimpanzee – has been released by an international consortium of scientists.
The chimp genome sequence, which consists of 2.8 billion pairs of DNA letters, will not only tell us much about chimps but a comparison with the human genome will also teach us a great deal about ourselves.
“The major accomplishment is that we now have a catalogue of the genetic differences between humans and chimps,” says lead author, Tarjei Mikkelsen of the Broad Institute in Cambridge, Massachusetts, US.
In keeping with previous studies comparing much smaller portions of the chimp and human genomes, the new comparison shows incredible similarity between the genomes. The average number of protein-changing mutations per gene is just two, and 29% of human genes are absolutely identical. What is more, only a handful of genes present in humans are absent or partially deleted in chimps.
But the degree of genome similarity alone is far from the whole story. For example, the mouse species Mus musculus and Mus spretus have genomes that differ from each other to a similar degree and yet they appear far more similar than chimps and humans.
Domestic dogs, however, vary wildly in appearance as a result of selective breeding and yet their genome sequences are 99.85% similar. So most of the differences between chimp and human genomes will turn out to be neither beneficial nor detrimental, in evolutionary terms.