Adaptations Chemicals Forces Genetics Earth Electricity Timeline 
Home Jnr Science Biology
Year 8

The basic theory of evolution, is that life started 4.5 billion years ago as an extremely simple organism.

Single celled prokaryotes and eventually through trial and error, began changing and evolving into the complex and diverse life we have today.

This process didn’t happen over night, it took billions and billions of years to occur.

Basics of evolution

The oldest known fossil is of Cyanobacteria. Dating back over 3.8 billion years!

This single celled bacteria was one of the first organisms present on earth.

Skipping a few million years of evolution we get to the trilobite. This organism is a distant relative of lobsters and is over 400 million years old.

They lived through the Paleozoic age.

Eventually organisms evolved into huge complex multi cellular organisms called dinosaurs.

Triassic, Jurassic, and Cretaceous areas are know for the dinosaurs which inhabited these areas.

Spinosaurus and tyrannosaurs rex from the cretaceous area, Desmatosuchus in the Triassic area and stegosaurus from the Jurassic period.

As you know, the larger dinosaurs died out. Although we don’t have Tyrannosaurs rex running around we do have one of his ancestors. The chicken.

The death of these dinosaurs allowed smaller animals, like mammals space and resources to grow an evolve.

And eventually man.

But how does evolution work?

Homo sapiens didn’t magically turn from apes to humans in a day. It took millions of years of trial and error for us to evolve into what we are today.

Fossils are brilliant to learn about evolution because they can show us how an organism changes, close relatives of an animal and when they used to exist.

Lets look at the fossil records of the common horse and see how it has evolved over time.

Click here to learn more on the evolution of the modern horse

There were two theories of evolution placed forward, One from Darwin, Which is now the accepted version and one from Lamarck.

Click here to learn more.  

The theory states that evolution occurs through natural selection.

This is where nature chooses what traits are good and what aren’t.

The video to the right demonstrates artificial selection of the Belgium blue cow.

Click here for more information on natural selection

Click here for a very simplistic tree of life.

Click here for  short test on natural selection and evolution