San Jose, Calif. – The first comprehensive comparison of the genetic blueprints of humans and chimps, an effort that explains what makes us so similar to our closest living relative – yet so strikingly different – was announced Wednesday by an international team of scientists.
“The differences shed light on our uniqueness,” said Dr. Eric Lander, director of the Broad Institute of Cambridge, Mass., and one of the principal investigators of the project.
The insights will contribute to medicine, because many of the differences relate to disease susceptibility.
Humans die from such illnesses as malaria, AIDS and Alzheimer’s disease, while chimps are immune.
Understanding what genetic differences contribute to chimps’ immunity could eventually help researchers develop human therapies, said Jim Sikela, a pharmacology professor at the University of Colorado Health Sciences Center, who studies primate genomes.
Sikela did not contribute to the newly published research but said scientists are already eager for the complete sequencing of other primate genomes, which will help them unravel evolutionary history and the changes that eventually gave humans the ability to walk, talk, use tools, ponder the future and build giant societies.
The genetic sequences of the most important parts of the human and chimp genomes are about 99 percent identical, according to the analysis by 67 researchers, including a team from the University of California, Santa Cruz. Part of the chimp genome is not shared by humans; part of the human genome is not shared by chimps.
When the genomes of the two species are compared more broadly, including nonfunctional “junk DNA,” they are 96 percent identical.
While that sounds like a close connection, people are far more closely linked to one another, the scientists explained. There is only a 0.1 percent difference between individual humans – in other words, there are one-tenth the differences among all humans as there are between humans and chimps.
The news, announced at a Washington, D.C., news conference, echoed the excitement of the first complete sequencing of the human genome in 2001.
“It adds great richness to something that was one-dimensional,” said Dr. Francis S. Collins, director of the National Human Genome Research Institute, who led the human sequencing project.
A large collection of papers, published Wednesday and Thursday in the journals Nature and Science, describe a broad range of chimp-based research.
Scientists believe humans and chimps shared a common ancestor 6 million years ago, then parted ways. How we changed, and why, has long intrigued scientists.
“The similarities between man and chimp have fascinated us across time,” said LaDeana Hillier of the Genome Sequencing Center at Washington University School of Medicine. “It is a privilege to see those very specific similarities at the molecular level.”
Denver Post staff writer Katy Human contributed to this report.
