Chp 12: The Bare Bones of Natural Selection p 135-146

"As an adult, the famous parasite Sacculina, a barnacle by ancestry, looks like a formless bag of reproductive tissue attached to the underbelly of its crab host (with 'roots' of equally formless tissue anchored within the body of the crab itself)--a devilish device to be sure (at least by our aesthetic standards), but surely less anatomically complex than the barnacle on the bottom of your boat, waving its legs through the water in search of food," p139.

I had to look this creature up.

from toptenz.net/top-10-zombie-parasites.php

Supposedly it tricks the crab into taking care of the primitive sac as if it were the crab's own eggs. I am amazed that this parasite has the ability to manipulate the actions of its host to help Sacculina complete its life cycle. Parasites like this make a strong case for the possibility of a zombie apocalypse. Rabies already infects and controls the brains of dogs and bats to increase its prevalence and infects humans. If a mutation causes a change in the rabies virus where it would exploit humans to extend its life cycle (creating a rabid, violent, and a human-munching desire) that might be the start of World War Z.

"Natural selection can forge local adaptation--wondrously intricate in some cases, but always local and not a step in a series of general progress or complexification," p140.

I couldn't agree more. Natural selection works as a response to the particular environment. Behaviors that were selected for created a dodo bird that was perfectly adapted to life on a predatorless deserted island (not wasting energy on flight, not wasting resources protecting the nest). Natural selection did not have the foresight to worry about losing these defense mechanisms in a world without a need for defenses. Once predators were introduced, the change was too rapid and the dodo's were doomed; the dodo's would have been better off with the consistent selection pressure of predators and nest attackers. Dodo's would have kept their ability to fly. Sometimes it concerns me that humans are constantly fighting natural selection, but at the same time I have to be compassionate enough. Humans are constantly allowed to survive with traits that would have made death inevitable in the earliest days of man. Ex. If I broke my leg, I wouldn't be able to hunt. If I had bad vision, a lion might capture me. If I needed a Cesarean section to deliver a child, I'd be a goner. We are constantly fighting natural selection, which is the beauty of man.