What was Darwin's explanation for the evolution of species?

Answer 1

Darwin believed and theorized that species competed for existence over many years and evolved to be what they are today. Species will battle for the fittest because they are on the food chain. For example, when a bear eats a fish the bear is ending the life of the fish and therefor the fish can't go on to reproduce and possibly evolve. The bear is also increasing his chance of living to reproduce by eating the fish. So, the species with the fittest genetics will most likely reproduce and pass on that genetics to the next generation. His explanation for the evolution of species was natural selection.

Answer 2

Basically from the very first form of life the organisms which were most able to survive and reproduce began to grow in greater number until there is competition for food or something. If by random chance there is a mutation that allows an organism to escape or prevail over competition e.g. it develops an ability to swim more deeply than other organisms. This will give it an advantage and therefore it will reproduce rapidly while other 'normal' organisms may die. Soon the deep water will become competitive and organisms that have further advantageous genetic mutations will emerge.

The whole process is called natural selection

A few things to note is that some people think that humans are more evolved than primates and other animals like fish. This is not true, if something is on this planet now it is just as adapted to survive as we are.

Also you have to realize that evolution on a grand scale e.g. reptile to mammal takes a very very long time, its not like a lizard gives birth to an elephant....

And finally 99% of mutations are either harmless or have no effect so it is very rare for an advantageous mutation to occur and for it to be any use