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Report: Humans, chimps should be in same genus

Tuesday, May 20, 2003 Posted: 9:54 AM EDT (1354 GMT)

Humans and chimps share 99.4 percent of their DNA, according to scientists.

WASHINGTON (AP) -- Chimpanzees are more closely related to people than to gorillas or other monkeys(sic) and probably should be included in the human branch of the family tree, a research team says.

The idea, sure to spark renewed debate about evolution and the relationship between humans and animals, comes from a team led by Morris Goodman at Wayne State University School of Medicine in Detroit.

Currently, humans are alone in the genus ****. But Goodman argues, "We humans appear as only slightly remodeled chimpanzee-like apes." He says humans and chimps share 99.4 percent of their DNA, the molecule that codes for life.

Some anthropologists were skeptical of the proposed classification.

The fact that chimps and humans are closely related and share a common ancestor about 7 million years ago is well known, said Richard J. Sherwood, an anthropologist at the University of Wisconsin. But that doesn't mean they belong in the same genus now, he said.

The report is being published in Tuesday's online issue of Proceedings of the National Academy of Sciences.

The battle over how humans are related to chimps, gorillas and other monkeys has raged since 1859, when Charles Darwin described evolution in "On the Origin of Species."

The dispute between religious and scientific factions got its greatest publicity in 1925 when John Scopes, a schoolteacher from the southern state of Tennessee, was convicted of teaching evolution.

And it continues to this day: the state of Kansas reinstated the teaching of evolution in 2001, 18 months after the state school board voted to drop it from classes. Alabama's school board voted to put stickers on biology books warning that evolution is controversial.

Goodman's team didn't address evolution directly but proposed that humans and chimps be considered branches of the same genus because of their similarities.

A genus is a group of closely related species. The human species, **** sapiens, stands alone in the genus ****. But there have been other species on the branch, such as **** neanderthalensis, or Neanderthal man.

Chimpanzees are in the genus Pan along with bonobos, or pygmy chimpanzees.

Goodman's proposal would establish three species under ****. One would be **** (****) sapiens, or humans; the second would be **** (Pan) troglodytes, or common chimpanzees, and the third would be **** (Pan) paniscus, or bonobo chimpanzees.

There is no official board in charge of placing animals in their various genera, and in some cases alternative classifications are available.

"If enough people get agitated by this and think it's something to be dealt with there may be a symposium that takes this as the central issue and determines if this is a reasonable proposal," Goodman said. "I think it's a reasonable proposal, of course, or I wouldn't have proposed it."

Goodman's paper cites a proposal by George Gaylord Simpson that chimps and gorillas be combined in one genus -- gorillas are in the genus Gorilla. Goodman says that, because chimps are more closely related to humans than to gorillas, they be added instead to ****.

Sherwood says Simpson made that proposal in 1963 and no one is arguing today to put chimps and gorillas in the same genus.

"To go hunting for an historical reference like that and then use it as the sole criteria for suggesting a major shift in primate systematics is difficult to take seriously," Sherwood said.

Reclassification of chimpanzees would cause major changes in the way anthropology students learn the relationships between various types of animals, an area already involved in the debate between evolution and creationism.

Walt Brown of the Center for Scientific Creation in Phoenix, Arizona, argues that since the sequencing of human and chimpanzee DNA is not complete, saying people and chimps are that much alike is "baloney."

"We have similarities with chimpanzees, but there are a heck of a lot of differences too," Brown said.

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Study: Chimps Belong In Human Genus

By Jennifer Viegas, Discovery News

Closer Than We Thought

May 20, 2003 Chimpanzees share 99.4 percent of functionally important DNA with humans and belong in our genus, ****, according to a recent genetic study.

Previous studies put the genetic similarity between humans and chimps at 95 to 99 percent, so the new figure suggests chimps and humans are even more closely related than previously thought.

Scientists analyzed 97 human genes, along with comparable sequences from chimps, gorillas, orangutans and Old World monkeys (a group that includes baboons and macaques).

The chosen genes are considered to be "functionally important" because they code for proteins, meaning that they can change amino acids in the body.

The researchers then took the DNA data and estimated genetic evolution over time. They determined that humans and chimps shared a common ancestor between 4 and 7 million years ago. That ancestor diverged from gorillas 6 to 7 million years ago.

The findings are published in the current Proceedings of the National Academy of Sciences.

According to Morris Goodman, one of the paper's authors and a professor of anatomy at Wayne State University School of Medicine, and his colleagues, the DNA information, combined with the ancestral links, should result in a new family tree, with the genus **** including humans, common chimpanzees, and bonobo chimpanzees. Chimps are currently classified in the genus Pan.

"Chimps are more like a human than a gorilla," said Goodman. "The traditional classifications need revising because, as scientists, we've been working under antiquated notions, such as Aristotle's 'Great Chain of Being,' in which animals were arranged in scales according to their degrees of 'perfection' beneath humans."

Goodman added, "In terms of culture, social behavior, language and other factors, we share many things in common with chimpanzees."

His colleague, Derek Wildman, agreed. "A lot of work focuses on the differences between chimps and humans," Wildman explained. "In reality we are quite similar to them."

Reaction from other scientists was mixed.

Both Todd Preuss, associate research professor in the Center of Behavioral Neuroscience at Yerkes National Primate Research Center at Emory University, and Michael Mahaney, a scientist in the Department of Genetics at the Southwest Foundation for Biomedical Research in Texas, believe that current genetic data should not be the only consideration for taxonomic classification.

Mahaney said, "We must consider a whole slew of characteristics, including behavioral evaluations, biological factors, distribution and morphology, in addition to underlying DNA."

They say further research is needed before any changes are made to our family tree.

Nona Gandelman of the Jane Goodall Institute hopes the PNAS paper will remind us that "chimpanzees are our closest living relatives. We should show them compassion."

Roger Fouts, co-director of the Chimpanzee and Human Communication Institute at Central Washington University, agrees with Goodman that chimps belong in our genus.

"Richard Dawkins perhaps provided the best visual for our link to chimps," Fouts told Discovery News. "Imagine taking the hand of your grandmother, who was holding the hand of her grandmother and so on down the line. 155 miles out, one of the women would be holding the hand of a chimpanzee."
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