Humans are more closely related to orangutans than chimps or gorillas, claims a controversial new theory that flies in the face of accepted science.
Photograph by: Dieter Nagl, AFP/Getty Images
Humans are more closely related to orangutans than chimps or gorillas, claims a controversial new theory that flies in the face of accepted science.
According to scientists Jeffrey Schwartz and John Grehan, humans and orangutans may have evolved from populations of an orang-like ancestor, rather than the chimpanzee, which is the mainstream scientific opinion.
Their work is published in the Journal of Biogeography.
The current scientific understanding is that humans' closest relatives are the common chimp and the bonobo, two species of chimpanzee. Scientists say that DNA evidence proves the human genome is closest to the chimp, then the gorilla and thirdly the orangutan, thereby making the chimp our closest ancestor. Humans and chimps share 98 per cent of the same DNA, compared to 96 per cent with orangutans.
But Schwartz and Grehan propose a radical argument that DNA is not the only indicator for evolution and that orangutans share many more biological features with humans than chimps. They say DNA analysis is problematic and argue the conventional chimpanzee theory is not backed up enough by fossil evidence.
Part of the reason many scholars have dismissed their work is because the scientific wisdom of the day dictates that DNA is the main indicator for evolutionary relatedness.
The scientists, at times, have been called "lunatics," says Grehan and their work often described as preposterous. But Grehan argues they have presented a sound contradictory theory, albeit a controversial one, which deserves proper debate and consideration from the scientific community.
"The evidence is there. We look like orangutans. We don't look like chimps. You have an orangutan ear," said Grehan, director of science at the Buffalo Museum of Science.
"Whether it proves to be true or false should be of interest. You would think scientists would want to debate, but DNA is big money and they're not going to turn around and say no it's not possible."
Orangutans have reddish-brown hair and long arms that stretch to the ground. They are native to Southeast Asia and live in trees and are known for their intelligence.
The scientists studied the physical features of apes and analyzed hundreds of fossils and concluded that early orangutans evolved into now-extinct apes and then early humans.
Among others, National Geographic and Natural History refused to print their research.
In a 2004 letter to Grehan, editor-in-chief of Natural History Peter Brown wrote that without DNA data sets to support the human-orangutan connection, the magazine felt it "would be publishing an open challenge to what seems to be settled science."
Grehan said there are 28 unique or almost unique traits that humans and orangutans share. For example, only orangutans and humans share the same ridges in their ears and certain features of the brain. Also, he said, the males sport beards and moustaches, while both genders share similar hairlines with humans.
"They are the only non humans to build houses. Great apes make nests but orangutans will add a roof. That, to me, is a very primitive house. They also mate longer - if they're up to it. And they mate face to face."
Wayne Goodey, a zoologist at the University of B.C., said he found some of the traits that the authors list questionable.
"Some of the traits listed seem to me to be of dubious value, though apparently they have been used before for other analyses," he said. "I have always found the chimp/Africa-affinity data convincing, as have nearly all other scientists, but if it proves to be incorrect, then once enough data has accumulated most people will accept it. My guess is: not yet."
The theory also challenges the evolution of humans in a biogeographical context. While conventional science teaches that humans evolved from apes in Africa, Grehan said they believe orang-like apes lived in not only Asia, but Africa and Europe, as well, about 13 million years ago. Grehan even argues Lucy - the 3.2-million-year-old ape skeleton that is the world's most famous early human ancestor - looks more like an orangutan.
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