New Research Chips Away at 'Irreducible Complexity'

From the Seed online article Time to Give It Up:

Lehigh biochemistry professor Michael Behe and his cronies in the intelligent design community have attempted to poke holes in evolutionary theory using an idea dubbed "irreducible complexity"—the notion that complex systems with interdependent parts could not have evolved through Darwinian trial and error and must be the work of a creator, since the absence of any single part makes the whole system void. However, a paper published in the April 7th issue of Science provides the first experimental proof that "irreducible complexity" is a misnomer, and that even the most complex systems come into being through Darwinian natural selection.

'We weren't motivated by irreducible complexity,' said Joe Thornton, an evolutionary biologist at the University of Oregon and a co-author of the paper. 'How complexity evolved is a longstanding issue in evolutionary biology per se, and it's once we saw our results that we realized the implications for the social debate.'

Thornton's team has been studying one example of a complex system in which each part defines the function of the other: the partnerships between hormones and the proteins on cell walls, or receptors, that bind them. The researchers looked specifically at the hormone aldosterone, which controls behavior and kidney function, and its receptor.

'Evolution assembles these complex systems by exploiting parts that are already present for other purposes, drawing them into new complexes and giving them new functions through very subtle changes in their sequences and in their structures,' Thornton said.

While the mutually dependent parts do not evolve to be perfectly complementary to one another, after molecular exploitation, they cleave together and create an illusion of irreducible complexity.