Darwin’s Voyage of Discovery

Darwin’s Epic Journey

• Charles Darwin- born in England on February 12th, 1809 (same day as Abraham Lincoln)

• Born in a time of changing thoughts about the Earth and about life

• Traveled the world in the HMS Beagle in 1831.• Developed a scientific theory of biological

evolution that explains how modern organisms evolved over long periods of time through descent from common ancestors.

Darwin’s Ideas

• 1- Species vary globally• 2- Species vary locally• 3- Species vary over time

Vary Globally

Flightless, ground dwelling birds• Rheas – grasslands of South America• Ostriches- grasslands of Africa• Emu- grasslands of Australia

Vary Locally• Different, yet related, animal species often

occupied different habitats within a local area.– Example- 2 species of rheas living in South

America. • One in nice climate grasslands of Argentina• One in the colder, harsher grass and scrubland to the

south.

– Example- Tortoises of the Galapagos Islands

Darwin’s Finches• Collected finches with varying sizes of beaks

Vary over time

• Darwin Collected Fossils• He noticed that some fossils of extinct animals

were similar to living species.– Example – Glyptodont vs. armadillo

Other Ideas that Shaped Darwin’s Thoughts

• An Ancient, Changing Earth• Lamarck’s Evolutionary Hypothesis• Population Growth• Artificial Selection

An Ancient Changing Earth

• Hutton and Lyell- Earth is extremely old and processes that changed the Earth in the past are still happening.– Examples• Volcanic eruptions- builds up• Erosion- tears apart

Lamarck’s Evolutionary Hypothesis• Suggested organisms could change during

their lifetimes by selectively using or not using various parts of their bodies.

• Also suggested that individuals could pass these acquired traits on to their offspring, enabling species to change over time.

Population Growth• Thomas Malthus- reasoned that if the human population

grew unchecked, there wouldn’t be enough living space or food for everyone.– Leads to war, famine, and disease

Darwin realized this applied to other organisms in a more obvious way. Maple trees- produce thousands of seeds. Most don’t sprout and of those that sprout, most don’t reach the age of reproduction.

WHICH ONES DID SURVIVE AND WHY?

Artificial Selection

• We pick which traits we want passed on by only allowing those with the desired trait to reproduce.