Humans are Much Closer to Orangutans than Chimpanzees – New Evidences

Path breaking research by scientists from the University of Pittsburgh and the Buffalo Museum of Science, headed by Dr Jeffrey H. Schwartz and Dr John R. Grehan, based on DNA analysis, indicates that humans are much closer to orangutans than chimpanzees. Till now the belief was that humans are closely related to chimpanzees. But this has never been supported by fossil evidence.

The new report says humans, orangutans, and early apes belong to a group separate from chimpanzees and gorillas. Schwartz and Grehan analysed hundreds of physical characteristics cited as evidence of evolutionary relationships among humans and other great apes, the chimps, gorillas, and orangutan. They selected 63 that could be verified as unique within this group. The rider was that they should not appear in other primates. Analysis of these features found that humans shared 28 unique physical characteristics with orangutans, compared to only two features with chimpanzees.

Schwartz and Grehan then examined 56 features uniquely shared among modern humans, fossil hominid and fossil apes. They found that orangutans shared eight features with early humans. Chimpanzees and gorillas were found to share only those features found in all great apes. Schwartz and Grehan have classified humans, orangutans, and the fossil apes into a new group called "dental hominoids," named after their similarly thick-enameled teeth.

One conundrum in the midst of all these evidences was that early human and ape fossils are largely found in Africa, whereas modern orangutans are found only in Southeast Asia. As an explanation they propose that the last common human-orangutan ancestor migrated between Africa, Europe, and Asia at some point that ended 12 million to 13 million years ago. Plant fossils indicate that forests once extended from southern Europe, through Central Asia, and into China prior to the formation of the Himalayas. Schwartz and Grehan say the ancestral dental hominoid lived and roamed throughout this vast area. As the Earth's surface and local ecosystems changed, descendants of dental hominoids became geographically isolated from one another.

The fascinating details of the study appears in the latest issue of Journal of Biogeography