Evolution

 

Charles Darwin proposed the theory of evolution by natural selection after travelling the globe to research fossils and geology for many years.

 

Darwin made 3 observations whilst he was out there:

1. Variation within species  

2. Best adapted survive  

3. Traits passed to offspring

 

Darwin then published his ideas in a book he wrote called On the Origin of Species (1859)

 

It received much criticism at the time because…

1. There was not enough evidence  

2. It was against religion  

3. Inheritance was not yet understood (Mendel later)

 

Another theory at the time rivalling Darwin's was that by a man called Jean-Baptiste Lamarck. Lamarck proposed that:

1. Changes that occur in an organism's lifetime are passed on to their offspring (e.g., an adult loses a finger→ offspring born without a finger)  

• This was of course disproven.

 

Speciation

 

A man called Alfred Russel Wallace co-discovered natural selection and went on to publish joint writings with Darwin 1858. 

 

This then prompted Darwin to release On the Origin of Species (1859) the following year.

 

Wallace gathered lots of information to support evolution but is also famous for speciation & warning colours on animals.

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Speciation is when a new species is formed through evolution. It has the following main steps:

1. A population of organisms gets split into two populations that live in different locations.

2. Each of the two populations evolve by natural selection so that they are adapted to their environment

3. Eventually, the two populations evolve to become so different that they no longer interbreed to produce fertile offspring. At this point they are two different species.