Thursday, September 17, 1998 Published at 14:47 GMT 15:47 UK
The most amazing experiment with life
An revolutionary experiment
In his weekly column our science editor Dr David Whitehouse describes one of the most amazing experiments ever performed.
Science is all about experiments. Ultimately every scientific idea has to be tested with an experiment that asks the universe how it works. The results of the experiment are absolute. This is the secret of the progress of science and the source of its great power.
Every once and a while along comes an experiment that changes the way you look at the world. Let me describe one that certainly changed things for me.
A few days ago I wrote a report on a tiny transparent worm called Caenorhabditis elegans that is soon to make scientific history.
Under the microscope as this tiny nematode sweeps its head gracefully from side to side it is not hard to see how the tiny creature got the 'elegans' part of its name. Yet this tiny spec of protoplasm holds the same secrets of life as other animals.
An organisms collection of genes is called its genome. The human genome consists of about 100,000 genes. Genes are strands of DNA that make proteins and it is the proteins working together that make us what we are.
The DNA in our genome contains all the genetic instructions to make all the tissues out of which we are made and all the chemicals that enable us to function. In a practical sense an organisms genome is its blueprint.
At that is what makes this tiny worm so fascinating. It is made up of exactly 959 cells and we will soon have its genetic blueprint, the first such blueprint for a multi-celled animal.
C elegans may be just a worm but its kinship to humans is breathtaking. Most human genes that have been discovered have a counterpart in this tiny worm. So similar in fact are many of our genes that they must have come from the ancient common ancestor of humans and worms many hundreds of millions of years ago.
And that is where the most staggering experiment with life comes in.
For over 500 million years humans and worms have followed separate lines of evolution. But biologists have been able to replace a C elegans gene with a human version of that same gene.
The worm can live just the same with its human replacement gene transplant. It goes to show just how related we are.
And indeed how related are all living things on Earth. Inside every cell of your body are genes that are shared by every other living thing on Earth no matter what it is.
And those genes have been passed down from living thing to living thing for hundreds of millions of years.
Your genes provide a direct and unbroken line between you and all the living things that have preceded you since life began on Earth.