Happy Birthday Mr Darwin!
It’s time to celebrate one of the most significant lives in our species. Charles Darwin’s remarkable theory permeates more of science every year expanding our perspective on life on this planet. In one of my favorite books looking at Darwin’s influence on science and our understand of ourselves, Dan Dennett best describes the theory as a “universal acid.”
Each ciliate has something called a micronucleus; this contains two complete versions of its genome. During sex, the micronucleus divides in such a way that each individual keeps one version of its genome for itself; it then gives an exact copy of this version to its partner. Afterwards, each individual fuses the two genomes (the one it kept and the one it got) to make a new micronucleus.This has three odd consequences. The first is that, by the end of sex, the two individuals have become genetically identical. It’s as if you and your mate began coitus as yourselves and finished as identical twins. The second odd consequence is that, partway through its life, a ciliate can radically alter its genetic make-up; genetically speaking, the transformation is so extreme that it’s as if you changed into one of your children. Talk about being reborn.