Ideas that Shaped Darwin’s Theory of Evolution

1) The influence of Geology

Charles Lyell demonstrated that the Earth was very old and that it changed over time

Darwin thought that if the earth could change, so could life on earth

2) The influence of Farmers: Artificial Selection

Artificial Selection = technique in which the intervention of HUMANS allows only selected organisms to exist

Meet the Super Cow

2) The influence of Farmers: Artificial Selection

Farmer altered and improved crops and livestock through breeding programs (eg. High yielding diary cows)

Darwin thought that if farmers could artificially select organisms, then nature (without human intervention), maybe also select organisms best suited to the environment to survive and reproduce

3) The Influence of Thomas Malthus (1766-1834): Population Controls Malthus observed that babies were being born

at a faster rate than people were dying, and that sooner or later there wouldn’t be enough living space and food

3) The Influence of Thomas Malthus (1766-1834): Population Controls To prevent endless population growth, famine,

disease and war would need to occur Darwin knew that animals produced many

offspring, but few survived; he thought that nature must determine that only some individuals survive and reproduce

Evolution of Natural Selection (Darwin) Natural Selection = process in nature that results

the most fit organisms producing offspring

It is believed that natural selection operates similar to artificial selection but over longer periods of time and without any controls or purpose

Individuals whose characteristics are well suited to their environment survive, individuals whose characteristics are not well suited to their environment either die or leave fewer offspring. Darwin called this “SURVIVAL OF THE FITTEST”

Raptors

Ice age

Natural Selection in Peppered moths Light colored moths were most common before

the industrial revolution in England. After trunks of tress had been stained by pollution, the dark colored moths became more common

Peppered Moths and Industrial Melanism The second half of the twentieth century

saw widespread implementation of pollution controls, thus trends reversed and light colored moths again dominated.

pollution created generally darker environment Clean up created a generally lighter environment

Selection Against Melanism

We may also call this ACCIDENTAL SELECTION which is the result of human activity which changes the genetic character of organisms. Another example is bacteria that are resistant to antibiotics.

Peppered Moths video

Comparing Darwin’s and Lamarck’s views