Well, I am back. And the reason was/is: introducing my son, Rei St. Aidan Galid (here with his grandma (my mom), born 27th May, 2010.)
A baby (and that includes you too) is an amazing piece of natural organic engineering. Imagine this: we all started as a single fertilised egg, the size of which is about 150 microns (just barely over the width of a human hair). Yet, over the course of development, from the cleaving of that egg to two, development of the embryo, and finally out of the trillions of different cells that make the flesh, blood, muscles, bones, hair, and what have you, is born a wailing and pissing infant, and pretty soon, like Baby Rei, a laughing, burping, pooping and milk-drinking-machine baby.
We have all heard of DNA and genes. Our genetic blueprint is made of the quaternary code of the four nucleobases (cytosine, guanine, adenine and thymine) that make up the information-bearing components of the DNA, and we have 3 billion of these bases. So much information (including making a whole human being) is packed in the nucleus of that tiny egg, but have you wondered how actually does the growing process decides (from that single cell) where is your head and feet, or where is your back and front? Well, that original egg have, for want of a better description, a north and south region, and between these 2 polar regions is a chemical gradient. As the cell divides and yiur genetic blueprint is transcribed, the different concentrations of this chemical from north to south decide your construction: more concentrations means the head, less, means your feet. Of course, it will be weeks before the embryo have feet and a head but by means of gene-directed protein encoding and gene siwtches, the development progresses.
If you want to learn more about developmental biology, I would reccomend a not-so-technical book by Sean B. Carroll, Endless Forms Most Beautiful: The New Science of Evo Devo and the Making of the Animal Kingdom.