WASHINGTON (Reuters) - Orangutans are notoriously slow and gentle, and a study of their DNA shows they have evolved in a similar way, researchers reported on Wednesday.
The findings, published in the journal Nature, could help conservationists do a better job of saving the endangered great apes and might provide insights into human health.
“In terms of evolution, the orangutan genome is quite special among great apes in that it has been extraordinarily stable over the past 15 million years,” Richard Wilson of Washington University in St. Louis, the genomics expert who oversaw the study, said in a statement.
“This compares with chimpanzees and humans, both of which have experienced large-scale structural rearrangements of their genome that may have accelerated their evolution.”
Devin Locke and colleagues sequenced DNA from two species of orangutans, the intelligent, reddish-colored great apes found only in the deepest forests of Indonesia and Malaysia.
Their two closest cousins — humans and chimpanzees — both have very rapidly evolving genomes. Chimps, especially, have been undergoing genetic change.
This change is driven in part by stretches of DNA called “alu” sequences. Locke has an analogy for them.
“In any novel, there are thousands, if not tens of thousands, of certain words like ‘the’ and ‘and,’” he said in a telephone interview.
“Alus are high-copy repeats. They make up over 10 percent of the human genome sequence. They are important for shaping genomes and they have also been implicated in moving sequences around the genome and lubricating the machinery.”
This is important for defining what makes a human being on the genetic level because the human gene map is puny compared to some other species, with only around 20,000 active genes.
Genetics experts realize it is not how many genes a species has that really matters, but what the body does with them. Comparing humans with our closest relatives can help show what makes us unique.
Locke and his team found that orangutans have relatively few alu sequences.
He does not believe that contributed to the rapid decline of orangutans, which are endangered. There are about 7,000 orangutans in Sumatra and 40,000 to 50,000 on Borneo.
“If humans didn’t populate the area, orangutans would be fine,” Locke said. “They are being forced into areas that humans find unsuitable for cultivation.”
Knowing about their genetic diversity can help zoos and conservationists preserve and protect the species, Locke said. For instance, the Borneo and Sumatran species of orangutans should likely not be interbred, and genetically diverse populations are usually more likely to survive.
In turn, the study has implications for human health. Inherited diseases are often linked to duplications in the DNA sequence that orangutans lack, Locke said.
And the sequencing work is showing how the price of mapping DNA is plummeting, Locke added.
“It probably cost about $20 million to do the first (orangutan) genome,” he said. The six genomes mapped for this study cost about $20,000 each.
Perhaps the DNA sheds light on the gentle nature of orangutans, as well, Locke said.
“Chimps ... once in a while try to gnaw somebody’s face off, and you think these orangutans are so nice,” he said.