Chimpanzees are more closely related to people than to gorillas or other monkeys and probably should be included in the human branch of the tree of life, 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 Homo. But Mr. 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 life.
The report was published in today’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 Tennessee schoolteacher John Scopes was convicted of teaching evolution.
And it continues to this day. Kansas reinstated the teaching of evolution this year, 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.
Mr. 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, Homo sapiens, stands alone in the genus Homo. But there have been other species on the branch, such as Homo neanderthalensis, or Neanderthal man.
Chimpanzees are in the genus Pan along with pygmy chimpanzees.
Mr. Goodman’s proposal would establish three species under Homo. One would be Homo (Homo) sapiens, or humans; the second would be Homo (Pan) troglodytes, or common chimpanzees, and the third would be Homo (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,” Mr. Goodman said. “I think it’s a reasonable proposal, of course, or I wouldn’t have proposed it.”