An international consortium of scientists has deciphered the genetic make up of the rhesus macaque, a monkey that shares a common primate ancestry with chimpanzees and humans. Researchers say the work will allow them to gain a better understanding of human biology and what drives human diseases, such as the virus that causes AIDS. VOA's Jessica Berman reports.

Ever since they produced a rough roadmap of the human genome in 2001, scientists have been trying to put our 20,000 genes in perspective.

The sequencing of the chimpanzee genome, our nearest non-human primate relative, has helped. Researchers found that around 98 percent of our DNA agrees with that of the chimp.

But experts say the two genomes are too similar to tell scientists much about what makes us uniquely human.

That's where the

Rhesus macaque

comes in. The macaque is the 25 million-year-old common ancestor of both chimps and humans.

The human and chimpanzee diverged six million years ago.

Richard Gibbs is director of the Baylor College of Medicine Human Genome Sequencing Center in Houston, which led a nine month project by 35 institutions to sequence the rhesus macaque.

"It is close enough to the human to be extremely like us and yet distant enough away to be a great mirror of what our genome contains," said Richard Gibbs.

The macaque genome agrees with the human genome 93 percent, according to Gibbs, who says that the seven percent difference gives investigators enough room to pinpoint important differences.

"So, for example if there's a difference between the chimp and the human, that the chimp and macaque are similar, you know that change is specific to the human lineage," he said. "And that's the relation between the three species that we were able to exploit in this study."

Rhesus macaques are the most widely used primate model species in biomedical research. Experts say having their DNA sequence will make it possible to use the animals less invasively and more productively in the laboratory.

More important, Gibbs say scientists now have a powerful tool to look for the origin of genetic mutations that are responsible for human diseases.

"Without this knowledge, the animal [humans] is really somewhat of a black box," said Gibbs. "That is, you know, you can put things in and take them out, and what you know about what's in the middle is less. And now we have this complete catalog of all the elements of the blueprint, we can build a comprehensive understanding of the physiology of the animal."

Researchers are beginning to sequence other non-human primates, including baboons, which get a form of heart disease similar to humans.

The sequence of the rhesus macaque appears with several related papers this week in the journal Science.