Wednesday, August 24, 2011

Unintelligent Design #1: Abdominal Aortic Aneurysms

This is the first in a series of medically relevant and quite practical examples of biology which is stupidly designed, or on the contrary is well-designed to make us suffer. For this first one, you might want to skip it if you can't handle gory pictures. The next installment in the series is here.

Your aorta is the main artery coming out of the top of your heart. It does a 180 degree turn and, giving off branches, continues down through the rear part of your abdominal cavity, finally bifurcating.

Unfortunately, there is a tendency, at the part of the aorta just below the arteries that go to your kidneys, for it to balloon out if something happens to drive the pressure up. This ballooned section (an aneurysm) can then rupture, and you can guess what happens when the main pipe out of your heart gets torn open. This is called an abdominal aortic aneurysm (AAA), and it's very, very bad. Why do they happen there at that spot, below the kidney arteries? Because as the blood is pumping downward, suddenly in that section there are no vasa vasorum anymore - "meta" blood vessels that supply the muscles in the walls of big, thick blood vessels - and suddenly the aorta's walls get thinner and weaker. Bad design! Interestingly, this is not the case in dogs, whose vasa vasorum continue past that spot. Dogs therefore don't get AAA's with nearly the same frequency. This is not academic. Starting in October, I will see these in person.

To visualize:

A real example:

It would seem that either evolution has produced something that is good, but not perfect in every respect, and there are features which happen to be better built in some other models of the self-replicating machines on this planet; or, we have a creator that wants us to have aortic aneurysms more often than dogs (or at least was careless). Therefore we humans are left having to scramble to fix these otherwise fatal events when they happen, all the while flying in the face of His plan.

I don't know about you but I would want to live in a universe where the first option is true. Fortunately we do.

Unintelligent Design #2 is here.

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