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 Editorials | At Issue | August 2006 
Why Doesn't America Believe in Evolution?
 Jeff Hecht - The New Scientist
Human beings, as we know them, developed from earlier species of animals: true or false? This simple question is splitting America apart, with a growing proportion thinking that we did not descend from an ancestral ape. A survey of 32 European countries, the US and Japan has revealed that only Turkey is less willing than the US to accept evolution as fact.
Religious fundamentalism, bitter partisan politics and poor science education have all contributed to this denial of evolution in the US, says Jon Miller of Michigan State University in East Lansing, who conducted the survey with his colleagues. "The US is the only country in which [the teaching of evolution] has been politicised," he says. "Republicans have clearly adopted this as one of their wedge issues. In most of the world, this is a non-issue."
Miller's report makes for grim reading for adherents of evolutionary theory. Even though the average American has more years of education than when Miller began his surveys 20 years ago, the percentage of people in the country who accept the idea of evolution has declined from 45 in 1985 to 40 in 2005 (Science, vol 313, p 765). That's despite a series of widely publicised advances in genetics, including genetic sequencing, which shows strong overlap of the human genome with those of chimpanzees and mice. "We don't seem to be going in the right direction," Miller says.
There is some cause for hope. Team member Eugenie Scott of the National Center for Science Education in Oakland, California, finds solace in the finding that the percentage of adults overtly rejecting evolution has dropped from 48 to 39 in the same time. Meanwhile the fraction of Americans unsure about evolution has soared, from 7 per cent in 1985 to 21 per cent last?year. "That is a group of people that can be reached," says Scott.
The main opposition to evolution comes from fundamentalist Christians, who are much more abundant in the US than in Europe. While Catholics, European Protestants and so-called mainstream US Protestants consider the biblical account of creation as a metaphor, fundamentalists take the Bible literally, leading them to believe that the Earth and humans were created only 6000 years ago.
Ironically, the separation of church and state laid down in the US constitution contributes to the tension. In Catholic schools, both evolution and the strict biblical version of human beginnings can be taught. A court ban on teaching creationism in public schools, however, means pupils can only be taught evolution, which angers fundamentalists, and triggers local battles over evolution.
These battles can take place because the US lacks a national curriculum of the sort common in European countries. However, the Bush administration's No Child Left Behind act is instituting standards for science teaching, and the battles of what they should be has now spread to the state level.
Miller thinks more genetics should be on the syllabus to reinforce the idea of evolution. American adults may be harder to reach: nearly two-thirds don't agree that more than half of human genes are common to chimpanzees. How would these people respond when told that humans and chimps share 99 per cent of their genes?
Brain Gene Shows Dramatic Difference From Chimp to Human
University of California, Davis
One of the fastest-evolving pieces of DNA in the human genome is a gene linked to brain development, according to findings by an international team of researchers published in the Aug. 17 issue of the journal Nature.
In a computer-based search for pieces of DNA that have undergone the most change since the ancestors of humans and chimps diverged, "Human Accelerated Region 1" or HAR1, was a clear standout, said lead author Katie Pollard, assistant professor at the UC Davis Genome Center and the Department of Statistics.
"It's evolving incredibly rapidly," Pollard said. "It's really an extreme case."
As a postdoctoral researcher in the lab of David Haussler at UC Santa Cruz, Pollard first scanned the chimpanzee genome for stretches of DNA that were highly similar between chimpanzees, mice and rats. Then she compared those regions between chimpanzees and humans, looking for the DNA that, presumably, makes a big difference between other animals and ourselves.
HAR1 has only two changes in its 118 letters of DNA code between chimpanzees and chickens. But in the roughly five million years s?nce we shared an ancestor with the chimpanzees, 18 of the 118 letters that make up HAR1 in the human genome have changed.
Experiments led by Sofie Salama at UC Santa Cruz showed that HAR1 is part of two overlapping genes, named HAR1F and HAR1R. Evidence suggests that neither gene produces a protein, but the RNA produced by the HAR1 sequence probably has its own function. Most of the other genes identified by the study also fall outside protein-coding regions, Pollard said.
Structurally, the HAR1 RNA appears to form a stable structure made up of a series of helices. The shapes of human and chimpanzee HAR1 RNA molecules are significantly different, the researchers found.
RNA is usually thought of as an intermediate step in translating DNA into protein. But scientists have begun to realize that some pieces of RNA can have their own direct effects, especially in controlling other genes.
The proteins of humans and chimps are very similar to each other, but are put together in different ways, Pollard said. Differences in how, when and where genes are turned on likely give rise to many of the physical differences between humans and other primates.
Researchers at UC Santa Cruz, the University of Brussels, Belgium and University Claude Bernard in Lyon, France, showed that HAR1F is active during a critical stage in development of the cerebral cortex, a much more complicated structure in humans than in apes and monkeys. The researchers found HAR1F RNA associated with a protein called reelin in the cortex of embryos early in development. The same pattern of expression is found in both humans and rhesus monkeys, but since the human HAR1F has a unique structure, it may act in a slightly different way. Those differences may explain some of the differences between a human and chimp brain.
The chimpanzee genome was published in Nature in 2005, showing that the DNA sequences of humans and chimps are more than 98 percent identical. The current work was funded by the Howard Hughes Medical Institute, the U.S. National Institutes of Health and other agencies. |
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