The idea that the orangutan is mankind's closest relative has never been popular in the scientific mainstream.

	William Parsons, Buffalo Museum of Science The new orangutan-like reconstruction of Australopithecus afarensis at the Buffalo Museum of Science. Click photo for larger image.

In fact, when University of Pittsburgh anthropologist Jeffrey Schwartz first advanced the idea 20 years ago, many of his colleagues rejected it out of hand, citing analyses that the genomes of chimpanzees and humans are almost 99 percent identical, while orangutans are genetically distinct.

But Schwartz's orangutan theory of human origins is not forgotten and last week got renewed attention at the Buffalo Museum of Science.

As part of a developing exhibit on human origins, the New York museum unveiled a painting that depicted a fleshed out version of Australopithecus afarensis. The 3.2 million-year-old fossil, popularly known as Lucy, may be the oldest common ancestor in the human family.

Unlike earlier reconstructions that favored chimp-like features, this version by the museum's scientific illustrator, William Parsons, looks more like an orangutan.

"It shows," said John Grehan, the museum's director of science and collections, "that you can get more than one answer out of the same evidence."

Neither the exhibit nor the painting is an endorsement of the orangutan theory, he emphasized, but they are meant to acquaint the public with competing theories of human origins, as well as provide some insights into the sociology of science.

"Every idea starts as a minority point of view," Grehan said, and sometimes ideas get overlooked or rejected because of scientific mindsets or assumptions. The orangutan theory, for instance, "isn't getting traction, but it's not necessarily the fault of the evidence."

Schwartz, a physical anthropologist who has been on the Pitt faculty for 30 years, based his theory on the morphological similarities ---- the physical characteristics ---- of humans and orangutans, not on their genes.

The orangutan, a name that means "man of the forest," is an endangered species. About 4¹*₂ feet tall, orangs are shy, reddish-haired apes that live in the trees on the Indian Ocean islands of Borneo and Sumatra.

Schwartz counts more than three dozen features that are shared uniquely by orangs and humans, from the ridges on the bottoms of their feet to the floor of their nasal passages.

Humans and orangs grow the longest hair of all primates and have the greatest separation between their breasts. Female humans and orangs produce four or five times more of the hormone estriol during menstruation and pregnancy than chimps and gorillas. The entire female reproductive systems of both species are remarkably similar.

"You can go on and on and on," Schwartz said. There's a long history of human and orang fossils being misidentified, he added, because the teeth and many other bones are so similar.

Bill Wade, Post-Gazette University of Pittsburgh anthropologist Jeffrey Schwartz is a longtime proponent of the proposition that orangutans are more closely related to humans than are chimpanzees. Click photo for larger image.

The reconstruction unveiled last week was not based on Lucy, a partial skeleton missing a skull that was unearthed in Ethiopia by Donald Johanson in 1974. Previous reconstructions have been based on bits and pieces of skulls, Schwartz noted.

"You could make it look however you wanted," said Schwartz of those earlier, chimp-like depictions of Lucy.

The new painting was based on a scan of another Australopithecus fossil, known as AL444-2, which was found at the same site as Lucy. Its skull is "very orang-like," Schwartz said, with front-facing cheekbones and a flat facial plane below the eye sockets. The brow ridges are thin, like those of orangs and humans, so they don't stick out like those of chimps and gorillas.

"Nobody is saying that Lucy is an orang," Schwartz said. Still, the similarities are intriguing, he maintained.

Other anthropologists aren't necessarily any more intrigued with the orangutan theory now than they were in 1984, when Schwartz outlined it in a paper in the prestigious journal Nature, or in 1987, when his book on the subject, "The Red Ape: Orangutans and Human Origins," was published.

"I'm not aware that anyone has given Jeff's idea more thought since the initial discussion and I don't think that anything has happened in the intervening years that would lead to it being more likely to be reconsidered," Andrew Hill, chairman of anthropology at Yale University, said last week.

"There is absolutely no evidence to refute the well-established finding that humans and chimpanzees are most closely related," agreed Maryellen Ruvolo, a biological anthropologist at Harvard University. "I was surprised to hear that Schwartz still believes that orangutans are most closely related to humans."

Orangutans, Ruvolo noted, are genetically very distinct from humans, chimps and gorillas. The strong genetic similarity between chimps and humans, she noted, was one of the main reasons why the federal government opted to spend millions to sequence the chimp genome. By comparing the chimp and human genomes, scientists hope to determine which genetic factors account for the physical and biomedical differences between the species.

Just last week, researchers at the University of Pennsylvania reported in the journal Nature that they had found a genetic mutation in humans that is not shared by chimps. The mutation, they suggested, led to the development of smaller, weaker jaws, which in turn may have allowed the cranium to grow in size to accommodate a larger brain.

Scientists are strongly divided on whether a single mutation could have had such a profound effect on human evolution. Schwartz is among those who doubt its significance, noting that Neanderthals somehow managed to have both big brain cases and substantial jaws.

It's not that genes are irrelevant, Schwartz said. Rather, the way that genes are regulated may be as important as the genes themselves in explaining the differences between species.

Harvard's Ruvolo, however, said genomic analyses include not only genes that code for proteins, but also the regulatory regions controlling gene expression ---- not to mention regions with no known function.

Grehan said he became intrigued by the orangutan theory when he read Schwartz' book several years ago. His interest increased when he tried to get critics of the theory to explain why orangs and humans could have so many physical similarities, while the genetically similar chimp could be so different from humans.

"I got nothing," he said, noting most anthropologists refuse to even discuss it.

Ruvolo, however, said she is "baffled" by the exhibit. The chimp-human relationship is widely accepted because it has stood up to scientific peer review ---- a process in which anonymous groups of scientists approve funding for projects or approve publication of findings after reviewing the evidence for the claims.

Grehan acknowledged that he could be criticized for the exhibit, but maintained that it was important "to bring to the public the process of science."

"This is really a brave and intellectually challenging thing that the museum has done," said Schwartz, noting that an updated edition of "The Red Ape" will be published later this year by Westview Press. "This, I think, will give the public an idea of the nature of science ---- its good and bad points."