3.2b Charles Darwin and Alfred Russel Wallace and the Theory of Natural Selection

Who was Alfred Russel Wallace?

• The Other Guy to Discover Natural Selection’

How did Darwin and Wallace work together?

Wallace and Darwin were co-discoverers of this new theory, which would eventually be called the theory of natural selection - or evolution through natural selection.

What book did Darwin write and what was it about?

‘On the Origin of Species by Means of Natural Selection’.

What was the reception of ‘On the Origin of Species by Means of Natural Selection’

impressive – as it was an immediate best-seller. There was extensive discussion and debate about the book.

What were the main points of Darwin’s book?

• Every species is fertile enough that if all offspring survived to reproduce, the

population would grow (fact).

• Despite periodic fluctuations, populations remain roughly the same size (fact).

• Resources such as food are limited and are relatively stable over time (fact).

• A struggle for survival ensues (inference).

• Individuals in a population vary significantly from one another (fact).

• Much of this variation is heritable (fact).

• Individuals less suited to the environment are less likely to survive and less likely to reproduce; individuals more suited to the environment are more likely to survive and more likely to reproduce and leave their heritable traits to future generations, which produces the process of natural selection (fact).

• This slowly effected process results in populations changing to adapt to their environments, and ultimately, these variations accumulate over time to form new species (inference).

What was the reaction of other scientists (at the time) to Darwin’s ‘Origin’?

Some of the ‘natural philosophers’ and researchers immediately accepted the idea.

What was the reception of Darwin’s book?

• Discussed and debated world-wide as a best-seller

• Some scientists immediately embraced evolution and natural selection.

• Other members of the scientific community were slow to accept the idea or even outright resistant (and this response often differed by country)

• The book produced a wide range of religious responses at a time of changing ideas and increasing secularisation. The issues raised were complex and there was a large middle ground

Which of the following issues raised by Darwin’s book continue to resonate today?

• It is still an ongoing discussion as societies attempt to reconcile religious belief with the ideas of Darwin and Wallace.

• Evolutionary theory is still a useful science that continues to develop.

• Geological records and fossil data continue to add depth to our understanding.