|
Chimps
should be part of human genus, scientists say
"We
humans appear as only slightly remodeled chimpanzee-like apes,"
argues Professor Morris Goodman of Wayne State University.
Associated
Press - May 20th, 2003
WASHINGTON,
May 19 — Chimpanzees are more closely related to people
than to gorillas or other monkeys 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 Homo. 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.
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 Tennessee school teacher John Scopes
was convicted of teaching evolution.
And
it continues to this day: 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,
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 bonobos, or pygmy chimpanzees.
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,” Goodman said. “I think it’s a
reasonable proposal, of course, or I wouldn’t have proposed
it.”
Richard
J. Sherwood, an anthropologist at the University of Wisconsin,
isn’t so sure. The fact that chimps and humans are closely
related and share a common ancestor about 7 million years
ago is well known, Sherwood said, but that doesn’t mean
they belong in the same genus now.
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 Homo.
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, Ariz.,
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. In their study,
Goodman and colleagues compared 97 genes from humans, chimpanzees,
gorillas, orangutans, Old World monkeys and mice.
Genes
from humans and chimps most closely resembled each other,
followed by orangutans and Old World monkeys. None of the
other creatures was closely related to mice.
Tracking
mutation rates in the genes, the scientists estimate that
the common ancestor of chimps and humans diverged from gorillas
about 7 million years ago, and then separated into two species
between 5 million and 6 million years ago.
|
Cosmos
of Happiness
