My website map
Tried and tested
planet is very old. Do you know how old? Well
it's four thousand six hundred million years old.
That's 4,600,000,000 years! And simple life has been around
for most of that period -- at least 3,500,000 years. That's
plenty of time to try out a system for making new life
to replace old, and this works just about perfectly. What's
more, very simple life forms - just single cells - long
ago began to join together to make more complicated
bodies with thousands or millions of cells. All these
new types of life were natural experiments to see what
worked and what didn't. Many didn't work and died out
- they became extinct.
types of bodies - organisms
- generally work when they happen to be in a part of the planet where
there's plenty of food and few enemies. Too little food, nasty climate
or vicious enemies spells disaster and means extinction unless an organism
can adapt in some way. This is where genes come in.