In the last several years, the intelligent design movement has attempted to move against science education standards for the teaching of evolution. The principal claim made by adherents of this view is that they can detect the presence of "intelligent design" in complex biological systems, that it could not possibly have been produced by an evolutionary pathway. As evidence, they cite a number of specific examples, including the vertebrate blood clotting cascade, the eukaryotic cilium, and most notably, the eubacterial flagellum Behe 1996a, Behe 2002). Behe calls the eubacterial flagellum, "Irreducibly Complex".

Of all these examples, the flagellum has been presented so often as a counter-example to evolution that it might well be considered the "poster child" of the modern anti-evolution movement.

An irreducibly complex structure is defined as ". . . a single system composed of several well-matched, interacting parts that contribute to the basic function, wherein the removal of any one of the parts causes the system to effectively cease functioning." (Behe 1996a, 39)
Source: The Flagellum Unspun; The Collapse of "Irreducible Complexity", Miller, 2003

Articles:

• The challenge of irreducible complexity, Behe, M., 2002. The challenge of irreducible complexity, Natural History 111 (April): 74., Natural History 111 (April): 74.
• "The Evolutionary Origin of Complex Features",
• May 8, 2003, Nature, 423:139-144, Lenski et al.
• Evolution by Intelligent Design: A Response to Lenski et al., Updated Nov. 2006, Casey Luskin
• The Flagellum Unspun; The Collapse of "Irreducible Complexity", Kenneth Miller, 2003
• YouTube - Irreducible Complexity: The Eye Could Not Have Evolved!

Books:
Darwin's Black Box: The Biochemical Challenge to Evolution , Michael J. Behe, 1996
Introduces the concept of "irreducible complexity" to show some structures are too complex to have been created randomly.

The Edge of Evolution, Michael J. Behe, 2006
"Many leading biologists of the late nineteenth and early twentieth centuries thought common descent was right, but that random mutation/natural selection was wrong."
Behe says on p. 65:
"I'll show some of the newest evidence from studies of DNA that convinces most scientists, including myself, that common descent is correct"
He goes on to say that humans surely have an ancestor of a different species, probably of a different genus, and possibly of a different family.

Only a Theory: Evolution and the Battle for America's Soul, Kenneth R. Miller, 2008,
Miller dismantles the scientific basis of intelligent design piece by piece. He does this by taking seriously the claims of intelligent design (though with tongue often in cheek), such as irreducible complexity, and looking at the biological facts and the dubious conclusions ID concepts would lead to. He turns to the peer-reviewed scientific literature to demonstrate that the two biological phenomena ID proponents say could not have evolved --blood-clotting proteins and bacterial flagella-- are now well-enough understood to fully rebut intelligent design.