27 February 2009

International Meeting Highlights Earth’s Origins and Futures

AAAS annual meeting topics range from Neanderthal DNA to climate change

Scientist Svante Pääbo led a team that completed a first draft of the Neanderthal genome.

By Daniel Gorelick
Staff Writer

Chicago — Thousands of scientists, students, exhibitors and members of the press from around the world spent five days debating and discussing the latest in science research, policy and education.

The 2009 annual meeting of the American Association for the Advancement of Science, held February 12–16, included lectures from Nobel laureates and high-ranking former and current government officials such as former Vice President Al Gore.

The broad theme of the meeting, “Our Planet and Its Life: Origins and Futures,” celebrated evolution and the 150th anniversary of the publication of On the Origin of Species by Means of Natural Selection, Charles Darwin’s seminal text on evolution. Lectures also recognized the 150th anniversary of the first commercial oil well and the discovery by Sir John Tyndall that carbon dioxide absorbs infrared radiation, the basis for the greenhouse effect by which heat from the sun is trapped within Earth’s atmosphere.

AAAS, founded in 1848, is a nonprofit organization whose mission is to “advance science and serve society” through initiatives in science policy, international programs and education.

SCIENCE AND GOVERNMENT

Outgoing AAAS President James McCarthy, an oceanographer from Harvard University, opened the meeting by discussing science policy during times of crisis.

U.S. President Abraham Lincoln, in the mid-19th century, recognized the value of science to the economy even in the midst of a terrible crisis, McCarthy said. During the U.S. Civil War, as the war between the northern and southern states plunged the country into turmoil, Lincoln founded the Department of Agriculture to bring cutting-edge agricultural technology from Europe to U.S. farms and signed the Land Grant College Act to support higher education.

McCarthy made an analogy to the current global financial crisis, calling on leaders to support science and technology in the midst of economic recession. Lincoln, McCarthy said, was the only United States president to hold a patent, which might have explained his great respect for science. The invention, an apparatus to buoy vessels, was never built.

At an annual meeting, scientists discussed microbial evolution of bacteria like these in light of new discoveries.

Former Vice President Al Gore, a Nobel laureate and a leading advocate for confronting global warming, addressed the meeting the following day. Gore exhorted scientists to speak out and educate the public about climate change. “We have a full blown political struggle to communicate the truth about our situation,” Gore said.

EVOLUTION, DARWIN, AND NEANDERTHAL DNA

Much of the meeting highlighted evolution, including lectures by evolutionary biologists Sean Carroll and Svante Pääbo.

Carroll, a professor of molecular biology and genetics at the University of Wisconsin, gave a historical perspective on the idea of evolution by natural selection and concluded that we are living during a Golden Age of evolutionary biology.

A century and a half ago, the field was dominated by naturalists, like Darwin and Alfred Wallace, who documented gross differences in plant and animal body forms by examining species and fossils in South America and the Malay Archipelago. Today, Carroll said, scientists are examining microscopic DNA and sequencing whole genomes of animals to learn how new species evolve and how similar species remain distinct.

To underscore this point, Pääbo, originally from Sweden but now head of the Department of Genetics at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, discussed his efforts to sequence the entire genome from a Neanderthal, a human species driven to extinction about 30,000 years ago. Overcoming problems of sample degradation, damage and contamination, Pääbo and his colleagues managed to extract enough DNA from Neanderthal fossils to sequence accurately most of the genome. New technology from private companies 454 Life Sciences and Illumina was essential for the project, Pääbo said.

Meanwhile, on the other side of the tree of life, scientists discussed how Darwin’s work could be applied to microbes — microscopic organisms such as bacteria that Darwin could not study due to technological limitations.

Norman Pace, a professor at the University of Colorado in Boulder, discussed how genome sequences have changed the textbook view of microbes. Traditionally, scientists broke down life into two categories: eukaryotes, those species whose cells contain a nucleus, an internal sac that holds DNA; and prokaryotes, organisms that do not contain a nucleus.

Pace argued that prokaryote is a “scientifically unjustified” term because it defines organisms by what they lack (a nucleus). He advocates rewriting the textbooks to call them microbes, and using more specific terms, such as archaea (a kingdom of ancient bacteria), when discussing functional evolution.

The notion that microbes evolved into eukaryotes in a sequential manner, a view still prevalent in textbooks, has also changed. DNA analysis has shown that eukaryotes are “as old as life,” and that they evolved alongside microbes, according to Pace.

For more about the AAAS meeting, see the author’s blog entries from the event on “Science Planet.”