The skull provides an indication of the consequences of the genetic differences. Professor Colin Groves, of the Australian National University (ANU), told IFLScience the skull is smaller than any other known orangutan male at a similar stage of development. On the other hand, the teeth are unusually large, particularly the canines. There are also reports of behavioral differences.
Despite this, P. tapanuliensis orangutans have not been totally isolated from their more numerous cousins. The authors report evidence of gene flow between the Sumatran populations long after they became separate species. Curiously, however, this all seems to have gone one way, apparently because members of the Tapanulis have sometimes come down from the mountains to look for company, while few, if any, of the north-Sumatran orangutans have made the opposite journey. In consequence, P. tapanuliensis appears to be a remarkably well-preserved sample of an ancestral orangutan population.
"Great apes are among the best-studied species in the world," said ANU's Dr Erik Meijaard in a statement. "If after 200 years of serious biological research we can still find new species in this group, what does it tell us about all the other stuff that we are overlooking: hidden species, unknown ecological relationships, critical thresholds we shouldn't cross? Humans are conducting a vast global experiment, but we have near-zero understanding of what impacts this really has, and how it could ultimately undermine our own survival."
P. tapanuliensis orangutans have survived in part because their homeland is too rugged and remote for much human interference, but that may change. A proposed dam would not only remove 8 percent of their range, but also cut across possible migration corridors, increasing inbreeding on both sides. Poaching could become a threat even if the land is unsuitable for the palm plantations that have devastated orangutans elsewhere.
Groves told IFLScience the Indonesian minister for the environment has been alerted to the importance of the issue, but at this point Groves could not point to any specific programs to protect the new species. He suggested those who wish to maintain the hominid family should donate to general orangutan conservation programs such as the Orangutan Conservancy or the Jane Goodall Institute.