Chimps 'should be reclassified as humans'

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The Independent Online

A molecular comparison of the chimpanzee with man has concluded that our closest living relative is closer than we ever imagined and that its genetic similarity even gives it a right to join life's most exclusive club - being human.

Researchers who have compared the working genes of chimps and humans believe that the two species are so alike at the level of their DNA that they should both be classified as members of the human genus Homo.

Traditionally chimpanzees, also known as Pan troglodytes, have been classified as belonging to the pongid family as they were considered to be closer to other non-human primates, such as gorillas and orang-utans, but the latest study by Morris Goodman of Wayne State University in Detroit puts chimps close enough to humans for them to become practically indistinguishable.

"What we found was that at the genetic level chimps are more like humans than gorillas. The finding would support those who want to extend legal controls to stop the abuse of chimps," Professor Goodman said. "Our results lend weight to the idea that it wouldn't be ethical to treat them in the way laboratory animals like rats or mice are treated," he said.

The research team found that some of the most important genes of chimps and humans share about 99.4 per cent of their genetic sequence, bringing them far closer together than the 98 per cent similarity which previous studies have suggested.

Professor Goodman explained that his study looked at the crucial "coding" or functional regions of 97 genes common to chimps and humans that have changed as a result of natural selection.

They also looked at rather more neutral "non-coding" regions of the genome where changes are more rapidly accumulated because they are less important. Here the similarity was less pronounced.

Most non-coding DNA -- which is usually not part of a gene and does not produce proteins -- is not closely scrutinised and shaped by natural selection and so on average evolves more rapidly than the DNA of working genes, which are responsible for the body's vital proteins.

The study, published in the Proceedings of the National Academy of Sciences, challenges the anthropocentric concept of nature that has dominated zoological classification since Aristotle who conceived a "great chain of being" from the lowliest creatures to the higher forms of life

Humans and our extinct relatives such as the Neanderthals, are classified as belonging to the Homo or hominid grouping based on anatomical comparisons but the researchers write: "This concept of greatly different 'hominid' and 'pongid' zones has perpetuated the widespread continuing use of the term 'hominids' to refer solely to humans.

"We humans appear as only slightly remodelled chimpanzee-like apes. We argue in the light of findings such as 99.4 per cent identity between humans and chimpanzees ... to place these two closely related genetic relatives in the same genus," they add.