Evolution: Darwin, Lamarck and Wallace

In a nutshell

Not everybody agreed with Darwin's theory of evolution by natural selection and other scientists had their own ideas.

Darwin's ideas were controversial

Charles Darwin wrote his book 'On the Origin of Species' in $1859$ however, many people opposed his ideas as they went against the idea that God created life.

They didn't know about mutations or genes at that time, so Darwin couldn't explain how characteristics arose or how they were passed on to the offspring. Not many other studies had been carried out investigating changes in organisms so there wasn't enough evidence to convince other scientists that his theory was correct.

Lamarck's theory

Jean-Baptiste Lamarck ( $1744-1829$ ) had his own theory of evolution. He proposed

Example

Using this theory, giraffes use their long necks to reach leaves on higher branches. As they use their long necks a lot, their offspring would have longer necks. This is how his theory would explain the length of a giraffe's neck.

Biology; Inheritance, variation and evolution; KS4 Year 10; Evolution: Darwin, Lamarck and Wallace

Wallace's theory

Alfred Russel Wallace developed very similar ideas to Darwin. He was researching how some organisms use warning colouration to deter predators. Warning colours are usually bright and in certain patterns to deter predators. The predators will learn to avoid organisms with these warning colours as they taste bad or will injure them.

Wallace proposed that the warning colouration must be favoured by natural selection.

He also found that some animal species may have evolved to resemble each other through a process called mimicry. The predators will also avoid the mimic as it looks like an unpleasant organism they have encountered before.

Example

A hover fly has similar warning colours to wasps.

Different hypotheses from similar observations

Scientists might develop different hypotheses from similar observations. This may be because of their different religious beliefs or who they are influenced by. The only way to see which hypothesis is correct is to find evidence that will support or disprove them.

Lamarck's hypothesis was disproved whereas Darwin's theory is now widely accepted. The discovery of genetics supported Darwin's hypothesis as it showed how organisms can pass genes to their offspring.

Fossils also show changes in organisms over time and antibiotic resistance supports evolution by natural selection.