November 27, 2012
Chemical Networks For The Origin Of Life Modeled By Researchers
April Flowers for redOrbit.com - Your Universe Online
Scientists have questioned how life began on a molecular level for a very long time. And now, an international team of researchers has presented evidence that sheds light on a possible mechanism by which life may have gotten a foothold in the chemical soup that existed early in the Earth's history.
Several competing theories have been previously proposed for how life got its start even before the first genes or living cells emerged. Although the theories are varied, they carry a common theme: a network of molecules that have the ability to work together to jumpstart and speed up their own replication. These are two necessary ingredients for life. Many researchers, however, have found it hard to imagine how such a molecular network could have formed spontaneously — without precursors — from the early chemical environment of Earth.
"Some say it's equivalent to a tornado blowing through a junkyard and assembling the random pieces of metal and plastic into a Boeing 747," said Wim Hordijk, a visiting scientist at the National Evolutionary Synthesis Center (NESCent).
Hordijk is a "wandering scientist" who has worked on six of the seven inhabited continents. He is a computer scientist who spends much of his time working on computational models of evolutionary science in collaboration with biologists, physicists, mathematicians, economist and even archeologists.
NESCent is a science center jointly operated by Duke University, The University of North Carolina at Chapel Hill, and North Carolina State University. The mission of this center is a synthesis of cross-disciplinary research, information, concepts and knowledge in emerging evolutionary science and the applications of that science. They are funded by a National Science Foundation Grant to provide an "an environment for fertile interactions among scientists."
Such networks might form more easily than many researchers originally thought, according to a previous study by Hordijk and Mike Steel of the University of Canterbury published in 2004, which used a mathematical model of simple chemical reactions to postulate these networks. Recently, in fact, biochemists have created such networks in the lab.
In the current study, which will be published in the journal Acta Biotheoretica, Stuart Kauffman of the University of Vermont joined Hordijk and Steel. The team analyzed the structure of the networks in their mathematical models to find a plausible mechanism by which these networks could have evolved to produce the building blocks of life recognizable today. Such building blocks would include membranes or nucleic acids.
"It turns out that if you look at the structure of the networks of molecules [in our models], very often they're composed of smaller subsets of molecules with the same self-perpetuating capabilities," Hordijk explained.
The models combined, split and recombined the networks to form new types of networks from their own subunits, thus indicating that these subsets of molecules could give rise to increasingly large and complex networks of chemical reactions. These larger, more complex networks, presumably, were the building blocks for life.
"These results could have major consequences for how we think life may have originated from pure chemistry," Hordijk writes.