Charles Darwin and his Voyage

Background on Charles Darwin

• As a youth, Darwin struggled in school• Father was a wealthy doctor• At age 16, Darwin entered school to study

medicine but was horrified by surgery• Darwin’s interests lay with the natural sciences• 1827, Darwin was sent to Cambridge

University to become a minister.

Darwin’s Voyage

• 1831, Darwin’s professor recommended him as an unofficial naturalist on a voyage on the HMS Beagle.

Darwin’s contributions

• Darwin developed a scientific theory of biological evolution that explains how modern organisms evolved over long periods of time through descent from common ancestors.

Patterns of biodiversity

• 1. Species vary globally– Noticed that different, yet ecologically similar

animal species inhabited separated but ecologically similar habitats around the globe

– Ex. Flightless birds , the rhea of South america, the ostriches on Africa, the emu on Australia

Patterns of Biodiversity

• 2. Species vary locally– Noticed that different, yet related, animal species

often occupied different habitats within a local area.

• Tortoises – shells designed for where they live and what they eat.

Patterns of Biodiversity

• 3. Species vary over time– Noticed that some fossils of extinct animals were

similar to living species.– Fossil record– Glyptodont and the armadillo

Darwin’s voyage

• Sailed on Dec. 27, 1831• 5 years, collect samples, took many

observations• 1859, published his ideas in a book called “On

the Origin of Species by Means of Natural Selection”

Influences

• In Darwin’s Day, the thought was that the earth was only a few thousand years old and not much had changed.

• Geologist James Hutton - - hypothesis on how geological processes have shaped the Earth.– Proposed forces beneath Earth’s surface can push

rock layers upward, over long periods of time = mountain ranges

Charles Lyell

• Wrote Principles of Geology in 1830, building off the work of Hutton

• Geological processes we see today mush be the same ones that shaped Earth millions of years ago.

Jean Baptist Lamarck

• Suggested organisms could change during their lifetimes by selectively using or not using various parts of their bodies.

• Pass acquired traits on to their offspring, enabling species to change over time = inheritance of acquired traits

• Ex. Giraffe neck• Why was this proven wrong??

Thomas Malthus

• Economist• Reasoned that if the human population grew

unchecked, there wouldn’t be enough living space and food for everyone.

• This does not happen, why?

• Darwin realized that most organisms do not survive and reproduce, which do and why… survival of the fittest.

Artificial Selection

• Nature provides the variations and humans select those they find useful

• Ex. Breeding horses, dogs…

• Darwin realized that the natural variations among individuals was very important because it provided raw material for change…evolution!

Evolution by Natural Selection

• 3 points that went into Darwin’s theory– The struggle for existence– Variation and adaptation• Adaptation – any heritable characteristic that increases

an organism’s ability to survive and reproduce in its environment.

– Survival of the fittest – • How well an organism can survive and reproduce in its

environment.

Natural Selection

• Process by which organisms with variations most suited to their local environment survive and leave more offspring.

Descent with modification

• Darwin suggested that over many generations, adaption could cause successful species to evolve into new species.

• Principle of common descent – all species, living and extinct- are descended from ancient common ancestors.

Evidence for Evolution

• Biogeography – study of where organisms live now and where they and their ancestors lived in the past.

• Patterns in the distribution of living and fossil species tell us how modern organisms evolved from their ancetors

Fossil Evidence

• Many recently discovered fossils form series that trace the evolution of modern species from extinct ancestors.

• Downfall to using fossils, hard to find complete set

Comparative Anatomy

• Homologous structures – structures shared by related species and have been inherited from a common ancestor– Same structure – different function

• Vestigial structures – inherited from ancestors but lost much or all of original function– Hip bones of dolphin

Embryology

• Looking at developmental stages of many animals with backbones.

• Similar patterns of embryological development provide further evidence that organisms have descended from a common ancestor.

Biochemistry

• New science, looking at DNA, RNA and proteins, beyond Darwin’s time.

• At the molecular level, the universal genetic code and homologous molecules provide evidence of common descent.