How does a fertilized egg become a human?

Wired, Issue 15.02 - February 2007

http://archive.wired.com/wired/archive/15.02/bigquestions.html?pg=3&topic=bigquestions&topic_set=

 

Imagine that you place 

a 1-inch-wide black cube in an empty field. 

Suddenly the cube 

makes copies of itself 

- two, four, eight, 16. 

The proliferating cubes 

begin to form structures 

- enclosures, arches, walls, tubes. 

Some of the tubes turn into wires, 

PVC pipes, structural steel, wooden studs. 

Sheets of cubes 

become wallboard and wood paneling, 

carpet and plate-glass windows. 

The wires begin connecting themselves 

into a network of immense complexity. 

Eventually, 

a 100-story skyscraper 

stands in the field.

That’s basically the process 

a fertilized cell undergoes 

beginning with the moment of conception. 

How did that cube know 

how to make a skyscraper? 

How does a cell know 

how to make a human 

(or any other mammal)? 

Biologists used to think 

that the cellular proteins 

somehow carried the instructions. 

But now proteins 

look more like 

pieces of brick and stone 

- useless without 

a building plan and a mason. 

The instructions 

for how to build an organism 

must be written in a cell’s DNA, 

but no one has figured out 

exactly how to read them.

 

- Steve Olson, author of Mapping Human History