UI prof rewriting Theory
of Evolution – again
SOURCE : http://www.news-gazette.com/story.cfm?Number=12204
By GREG KLINE
© 2002 THE NEWS-GAZETTE
Published Online August 25, 2002
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UI prof
rewriting Theory of Evolution – again
 N-G photo by Robin Scholz |
| University of Illinois microbiologist Carle Woese, who added a third branch of life to the evolutionary tree in a major breakthrough in the late 1970s, talks about his new theory on the origin of cells in his office/lab at Morrill Hall on the UI camps in Urbana. |
Time was, scientists knew, just knew, there were only two fundamental branches of life on the evolutionary tree: bacteria and the eukaryotes, the latter from which stemmed animals like us, plants and other organisms with visible cellular nuclei.
Then Woese, a University of Illinois microbiology professor, came along in the late 1970s and said no, he had been studying genetic code, comparing eukaryotes, bacteria and some things everybody thought were bacteria, and it turned out those things everybody thought were bacteria were actually something else.
So a third branch – archea, microorganisms that thrive primarily in extremely harsh environments – got added to the evolutionary tree, and a new crop of biology texts eventually sprouted around the world.
Woese received a MacArthur Foundation “genius” grant in 1984 and the National Medal of Science in 2000 as a result of his groundbreaking work.
A lot of folks would have called it a career, found some place more comfortable than a cluttered lab in Morrill Hall to put up those feet clad in New Balance running shoes, and somewhere more comfortable than a rickety office chair in which to lean back that head with the shock of white hair. Woese is 74.
Instead, Woese is engaged in rewriting the Theory of Evolution. Not the whole thing, mind you, but a key part known as the Doctrine of Common Descent, which says all life on Earth descended from one primordial form, in a sense one protocell, some 3 billion years ago.
Like the two branches on the evolutionary tree before it, this has been scientific dogma, although Woese says there have been scientists who thought things didn't quite work that way. Darwin himself left other possibilities open.
“Even in Darwin's time, they used to speculate about these things,” Woese said recently. “There was this sort of background of loose thinking.”
Questions arose in Woese's mind not long after he added the third branch to evolution's tree. OK, he thought, we've got these branches, so how did we get those? What came before that? Why three? How did it all come together?
Woese said his ideas started to come together around 1982 – “the germs were there.” He spent the next 20 years off and on putting them through their paces and refining them, even as technology made it possible to probe more genomes in more detail on computers with more power to sift large amounts of data.
“There are enormous databases now of gene sequences,” Woese said. “We kind of tease out understanding from those. All this rides on a tide of technological advance.”
Then, Woese published his new theory of cellular evolution in the Proceedings of the National Academy of Sciences earlier this summer.
Life didn't begin with one primordial cell, he theorizes in his paper “On the evolution of cells,” but with a large number of loosely organized sort of pre-cells. They existed in a communal environment, swapped genetic material extensively and freely traded biological inventions with each other – so-called “horizontal” transfer – to a point where some developed a new ability.
They could translate nucleic acid sequences, basic stuff of life at that point, into protein sequences, basic stuff of life as we know it now.
Woese compares it to the human development of language and the possibilities opened by the ability to express things symbolically. In effect, the more primitive code of nucleic acids was translated into a new alphabet of amino acids forming the protein words that made up the marching orders for evolution.
As language sets us apart from other animals, “translation” set these pre-cells apart, solidifying their forms, letting them become cells as we conceive of cells and capable of evolving vertically – into more advanced forms – in the Darwinian sense. Eventually, three dominant cell lines emerged.
“It's certainly a very provocative theory,” said John Cronan, head of the UI Microbiology Department. “My personal guess is he's right.”
Cronan said the scientific community's reaction to Woese's paper probably won't really start rolling until this fall, when academic scientists in particular return from summer break.
Woese, in cutting against the grain of conventional scientific wisdom, is bound to attract criticism, but in the past, his critics more often than not have come to realize he's right, Cronan said.
“He is an extraordinarily original thinker,” Cronan said. “We all kind of hold him in awe, I guess.”
Meanwhile, Lehigh University biochemist Michael Behe isn't sold on Woese's new theory, which he called “pretty much raw speculation,” but he does see value in it.
Behe, author of the book “Darwin's Black Box,” is a proponent of “intelligent design,” the idea that while evolution may have proceeded as Darwin described, only planning by some higher intelligence can explain the irreducibly complex biochemical machines at root of the evolutionary process and of life.
To Behe, Woese's paper highlights the implausibility that life in all its complexity just sort of happened in the kind of jerry-built fashion Woese describes.
“Parts of nature look like they were intelligently arranged,” he said. “They were made for a purpose. Physics and chemistry just can't account for it.”
But others, Woese's UI colleague microbiologist Gary Olsen for one, said there's ample support for the ideas Woese advances, in the genes and genetic processes scientists are studying in ever greater detail.
There are, for instance, “highly conserved” genes, common to and serving similar purposes in living things.
Reproduction is one big horizontal gene transfer, from parents to their children. Likewise, bacteria trade genes to gain new qualities, such as antibiotic resistance, and viruses can incorporate their genes into other genomes. Woese, in fact, thinks viruses may be vestiges of the process that led to cells, designs that didn't make it to full-fledged cellhood as it were.
Another leading biologist, University of Colorado Professor Norman Pace, said we might even see the process Woese describes in action today if we could drill below the surface of Mars. Pace, an expert in evolutionary processes who earned his doctorate at the UI, has advised NASA on plans to look for evidence of life off Earth.
“I'm completely convinced that Carl Woese has done more for biology than anybody since Darwin,” said Pace, a professor of molecular, cellular, and developmental biology. “It's like sitting in Darwin's garden talking about the origin of species, sitting with Carl Woese talking about the origin of cells.”
Woese demurs at the comparison to Darwin. He said he hopes others will try to poke holes in his theory; that's what theories are for, and in this case also to prod biologists to think outside classical boundaries.
Asked why anybody but biologists would care where cells came from billions of years ago, Woese chuckled and responded: “Where'd you come from? This is a forever, perennial question: ‘Where do I come from?' I'm just trying to construct a part of that road.”