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Wednesday, Jan. 11, 2006
I.D. 'revolution' gets its comeuppance
By ROWAN HOOPER
The year 2005 was when, shockingly, "intelligent design" almost got on the syllabuses of American science classes. But then 11 rational parents in Pennsylvania took their school board to court, and, just before Christmas, the presiding judge delivered a crushing verdict.
Judge John Jones ruled that intelligent design is not science, but merely creation science in disguise. In declaring its teaching in schools to be unconstitutional, he said that the Dover District School Board had acted with "breathtaking inanity" in deciding to do so.
In a judgment that was also implicitly critical of President George W. Bush's views -- he supports the teaching of intelligent design as a supposed means of telling the "other side" of the story -- Judge Jones wrote: "The goal of the intelligent design movement is not to encourage critical thought, but to foment a revolution which would supplant evolutionary theory with intelligent design."
God was banished from the classroom.
The irony in all this is that last year scientists found some amazingly clear insights into evolution in action, and into the still strong effect that natural selection is having on humans today.
In what would perhaps annoy advocates of intelligent design the most, researchers have used genetic data to home in on the date when the last common ancestor of humans and chimpanzees lived. The answer? We split from chimp ancestors between 5 and 7 million years ago.
Creationists, with their heads stuck firmly in the sand, think the Earth was formed 10,000 years ago, so they probably won't be bothered about the new work. But still, I'll bet they are secretly afraid of the ever-mounting pile of data supporting our evolutionary origins.
Sudhir Kumar, director of the Center for Evolutionary Functional Genomics in the Biodesign Institute at Arizona State University, and colleagues, used the molecular-clock method to examine 167 different gene-sequence sets from humans, chimpanzees, macaques and mice. This allowed them to compare the number of mutations in the DNA sequence of a species, in comparison with other species, in order to gauge the first species' rate of evolutionary change. Thus they were able to more precisely establish when we split from our common chimp ancestor.
Previous estimates from molecular and fossil studies had placed the split anywhere from 3 to 13 million years ago.
Over millions of years, it's relatively easy to see evolutionary change. There are fossils, for one thing, and we can document the incremental changes that led from a chimp-like ancestor to modern humans. But what about recent changes? There haven't been big anatomical changes in humans in the last 50,000 years -- but does that mean we haven't been evolving?
No. It's just that it's harder to find evidence for it. Until recently we didn't have the technology that allowed us to look.
But again, research last year uncovered compelling evidence that more than 1,800 human genes had undergone evolution by natural selection.
Robert Moyzis and colleagues at the University of California at Irvine used the tools of molecular biology to detect genes that have been maintained in the human population through positive selection, as opposed to random chance. They scanned 1.6 million markers of human genetic variability -- markers known as single nucleotide polymorphisms (SNPs). The researchers found that 1.6 percent of the SNPs showed signs of having undergone natural selection recently, in the last 10,000-50,000 years.
Most of the roughly 1,800 genes, some 80 percent of them, were involved in one of a few key biological areas: reproduction, host-pathogen interaction, neuron function, cell division and DNA and protein metabolism. This is not surprising, Moyzis says, because these areas will all have changed with the development of human culture that took place over the last 10,000-50,000 years. We changed from being hunter-gatherers to farmers, and this shift affected longevity, reproduction, dietary intake and the spread of infectious diseases.
Many more studies last year showed evidence for evolution at the genetic level. In October, an international team of researchers published the complete sequence of the chimpanzee genome, our closest relative. Comparing it with the human genome will show which genes have changed, and this will give us further insights into our evolutionary history.
Also last year, the genome of the virus responsible for the 1918 flu pandemic that killed millions was sequenced as well. It turns out that the lethal virus started as a bird-flu virus, then mutated -- which is precisely the event that is now worrying governments and scientists around the world as bird flu continues to spread from East Asia.
Meanwhile, other work last year showed how one species changes into another, thus answering Darwin's central question as to what is the origin of species.
All in all, it was a vintage year for the study of the subject that underpins every area of biology: evolution.
But let's give the last word to the magnificent Judge Jones, one of my people of the year, 2005.
"The overwhelming evidence at trial," Jones wrote, "established that intelligent design is a religious view, a mere re-labeling of creationism, and not a scientific theory."
A book of Natural Selections columns translated into Japanese, "Nou to sekkusu no seibutsugaku (Evolution, Sex and the Brain)," is published by Shinchosha.
Rowan Hooper is a biologist at Trinity College, Dublin. He welcomes readers' comments at email@example.com