Within apes (superfamily Hominoidea), the gibbons diverged during the early Miocene (between 24.1 and 19.7 mya, according to molecular evidence) and the orangutans split from the African great ape lineage between 19.3 and 15.7 mya. Israfil and colleagues (2011) estimated based on mitochondrial, Y-linked, and X-linked loci that the Sumatran and Bornean species diverged 4.9 to 2.9 mya. By contrast, the 2011 genome study suggested that these two species diverged around 400,000 years ago, more recently than was previously thought. Also, the orangutan genome was found to have evolved much more slowly than chimpanzee and human DNA. A 2017 genome study found that the Bornean and Tapanuli orangutans diverged from Sumatran orangutans about 3.4 mya, and from each other around 2.4 mya. Orangutans travelled from Sumatra to Borneo as the islands were connected by land bridges as parts of Sundaland during recent glacial periods when sea levels were much lower. The present range of Tapanuli orangutans is thought to be close to where ancestral orangutans first entered what is now Indonesia from mainland Asia.