Genetic code of chimpanzees unveiled
The chimp genome sequence not only explains more about chimps but its comparison with the human genome also gives a lot of details about the human beings.health and fitness Updated: Sep 01, 2005 16:36 IST
Scientists in the US have unveiled the genetic code of chimpanzees, the closest living relative of human beings, and a new comparison of genomes of the two beings shows incredible similarity.
The chimp genome sequence, which consists of 2.8 billion pairs of DNA letters, not only explains more about chimps but its comparison with the human genome also gives a lot of details about the human beings.
The new study was conducted by Tarjei Mikkelsen of the Broad Institute in Cambridge, Massachusetts, and other scientists.
"The major accomplishment is that we now have a catalogue of the genetic differences between humans and chimps," says Mikkelsen.
The average number of protein-changing mutations per gene is just two, and 29 per cent of human genes are absolutely identical. What is more, only a handful of genes present in humans are absent or partially deleted in chimps, New Scientist reported Mikkelsen as saying.
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, Mikkelsen said.
Domestic dogs, however, vary wildly in appearance as a result of selective breeding and yet their genome sequences are 99.85 per cent similar.
Comparing the two types of mutations allowed the team to spot genes that have had changes favoured by natural selection while taking into account the background mutation rate. And 585 of the genes studied in this set - many involved in immunity to infections and reproduction - had more protein-altering mutations than silent ones.
According to Mikkelsen, these will be a good place to look for genes that make humans different from chimps.