Twins for blind orang-utans give hope for species
Sydney Morning Herald
Thursday February 3, 2011
WHEN it comes to raising a family, orang-utans go for quality, not quantity.Females have their first infants about age 15 but then the average time between subsequent births is eight years.The mothers are patient and take great care of their young, carrying them constantly for the first 12 months, breastfeeding them for three or four years and then keeping them close until they are about seven or eight.This very slow rate of reproduction makes the tree-dwelling apes - only found in Sumatra and Borneo - particularly vulnerable to hunting, disease and the destruction of their rainforest habitat for palm oil and pulp paper plantations, says the founder of the Australian Orang-utan Project, Leif Cocks. "It's why they're prone to extinction."So the birth of orang-utan twins - a male and a female - in a Sumatran sanctuary funded by the organisation has been a double cause for celebration, Cocks says.In another unusual twist, both parents are blind. The mother, Gober (thought to be about 40 years old), was brought to the Batu Mbelin orang-utan quarantine centre in 2008 because she was at risk of being killed for raiding villagers' crops.Forty may sound old but it is thought female orang-utans may be able reproduce into their 50s.The father, Leuser, was kept illegally as a pet before he was rescued in 2004 and released back into the jungle. Sadly, two years later he was blinded by rifle pellets fired by villagers and was returned to the centre."The parents aren't able to survive in the wild, so they are living in the centre permanently, but we hope their offspring will join the release program," Cocks says.Since the quarantine centre was established in 2002, more than 200 orang-utans have been brought there for health checks and care. More than 130 of them have been transferred to a re-introduction centre in Jambi for release into the Bukit Tigapuluh National Park, he says.The twins, born on January 21, also arrived in an auspicious month for orang-utan research, with the publication last week of the draft sequence of the genetic code, or genome, of a female Sumatran orang-utan, called Susie, from a Texan zoo.It cost about $20 million to work out the original sequence but the team then sequenced the DNA of five more Sumatran and five Bornean orang-utans at an additional cost of about $20,000 each.The results, published in the journal Nature, show that human and orang-utan genomes are about 97 per cent identical, making these tree dwellers a more distant relative to humans than chimpanzees, which are about 99 per cent similar.The DNA study also finally settled decades of debate about the two groups of orang-utans, showing the apes living on Borneo and Sumatra are two different species. The researchers estimate they diverged about 400,000 years ago, much more recently than earlier estimates of about 1 million years ago.Dr Richard Wilson, the director of Washington University's Genome Centre, which led the research, says another surprising discovery was that the orang-utan genome has evolved much more slowly than that of chimpanzees and humans. It hasn't undergone the same large-scale duplication or deletion of sections of DNA and other structural rearrangements of their codes."In terms of evolution, the orang-utan genome is quite special among great apes in that it has been extraordinarily stable over the past 15 million years," Wilson says.The Sumatran orang-utans were found to be more genetically diverse than the Bornean ones, of which there are about 40,000 to 50,000 left. Genetic diversity helps populations to stay healthy and adapt to environmental changes but it is not enough to ensure their survival, says the team leader, Dr Devin Locke."Orang-utans spend more than 95 per cent of their time in the trees. All the genetic diversity in the world can't save them in the wild if their habitat is destroyed," he says.