Someone posted a comment on one of my articles (“Stop Flogging the Piltdown Man“) that’s about two years old. In the comments I had mentioned the blood-clotting cascades of horseshoe crabs, reptiles, and mammals. From the question, I know that she’d been listening to ID-ers: “Please post a biochemical explanation… I don’t understand how only some of the blood would clot.” Instead of dashing off to work, I started to do her research for her. Since the question is still being asked, I’m posting my answer here:
who ever said that only some of the blood would clot? In horseshoe crabs, all of the blood clots using only one step to produce clots. It just works more slowly.For a simple example of “irreducible complexity” in the real world, think of architecture. Builders use supports when they build an arch; then then they take those supports away and have a structure that will fall if any one element is removed.
First of all, read “Irreducible Complexity as an Evolutionary Prediction“. In 1918, Herman Muller, showed how evolution of a complex system and its subsequent modification would inevitably create systems that required all their parts to work. This article gives a reference to the original paper from 89 years ago.
Second, you will find the biochemical explanation on the Web site of Ken Miller, a working scientist, which I am not. So read “The Evolution of Vertebrate Blood Clotting“. If that doesn’t satisfy you, or if it’s hard to understand because of the specialized terms, there are lots of biology tutorials on the Web. Actually, I think that Miller’s site has a link to an online biology text book.
Thousands of scientists have spent millions of hours working this out. Don’t accept rhetorical tricks as a substitute.
