Steve Jones explains the evolution of clots — after explaining why “intelligent design” is the “logic of ignorance”:
The ID crew, to use Darwin’s own phrase, “look at an organic being as a savage looks at a ship, as at something wholly beyond [their] comprehension”. The first Hawaiians to cast eyes on Europeans were so astonished by their great vessels that they thought their builders to be gods. The ID argument is just the same. It is the logic of ignorance, idleness and incuriosity: I am very smart, even I do not understand this, so why bother to explain it except by bringing in God (if necessary under an alias)?
How did clots evolve?
The clotting machinery is an icon of just how complex life may be. Designers love it: for to staunch the flow needs a cascade of a dozen or more enzymes that work like a row of toppling dominoes. Two interacting pathways meet at a crucial junction point.One is set off by a change in acidity after a cut, while the other acts when it picks up chemical cues from damaged cells. An injury sets off a chain reaction until the job is done and, if any step goes wrong, the whole system collapses. How could such a complicated machine evolve from simple beginnings? What use is part of a clot?
Much better, in fact, than no clot at all. Plenty of animals manage with just a few parts of the machinery and DNA shows that — like the eye — the rickety apparatus that stops us from bleeding was assembled from random bits that just happened to be hanging around.