- Charles Darwin proposed the theory of evolution through natural selection in 1859 after observing species variation on the Galapagos Islands. His theory built upon earlier ideas from scientists like Jean-Baptiste Lamarck and Thomas Malthus. - Evolution occurs as inherited traits increase the chances of survival and reproduction in an organism's environment through natural selection and adaptation over many generations. The fossil record provides evidence of how species have changed over time. - The earliest life on Earth was microbial and existed in the oceans around 3.8 billion years ago. Oxygen levels increased around 2.2 billion years ago allowing complex eukaryotic cells and later multi-cellular organisms to evolve. Major extinction events punctuated this pattern

1. History of Evolution
• 1831, Darwin, naturalist on H.M.S. Beagle
• Galapagos, Coast of S. America
• Darwin (1831) – naturalist who proposed the
theory of evolution (1859) On the Origin of
Species
• James Hutton(1785)– earth is millions, not
thousands of years old
• Thomas Malthus (1798) – predicted that the
population of earth would exceed it’s resources

2. Cont.
• Jean-Baptiste Lamarck(1809) – proposed that
inheritance was acquired (1st
mechanism for
organisms changing over time)
• Charles Lyell (1833)- proposed that the process
occurring now have shaped the earth for long
periods of time; published Principles of Geology
• Alfred Wallace (1858)– contemporary of Darwin,
speculated on evolution through natural
selection

3. Theory of Evolution
• Fitness – individuals ability to survive and
reproduce in it’s environment
• Adaptation – inherited traits/characteristics
that increase the chance of survival
• Artificial selection – humans manipulate
traits
• Natural selection – inherited over time by
the process of nature (cannot be seen
directly)

4. • Over time organisms produce different
structures, establish different niches, or
occupy different habitats – descent with
modification
• Fossil record supported Darwin’s theory
• Fossil record shows how species have
changed overtime or died

5. Formation of Earth
• 4.6 billion years old (universe 15 billion)
• Elements arranged themselves by
densities creating the planet (radioactive
decay creates heat, core heaviest metals)
least dense formed early atmosphere (H
and N)
• Atmosphere was toxic to life as we knew it
(it was what we didn’t know could exist in
this environment, cyanobacteria)

6. Cont.
• 3.8 billion, earth cooled enough to allow
water to remain liquid, creating rain
• Under these conditions, organic
compounds were formed (building blocks
for life)
• DNA is transcribed into RNA then
translated into proteins

7. Oxygen-evolution
• 2.2 billion increase in oxygen allowed
organisms to evolve (move from water to
land)
• 2 billion eukaryotic cells (nucleus)
appeared, endosymbiotic theory proposes
that eukaryotes evolved from prokaryotic
communities

8. Geologic Time Scale

9. Cont.
• 90% of earths history occurred during
Precambrian (life only existed in the water)
• Paleozoic Era – abundance of marine life
• Cambrian – hard parts appear, most
animal phyla evolve
• Devonian – vertebrates appear
• Mass extinction occurs
• Mesozoic Era – rise of dinosaurs and
flowering plants

10. Cont.
• Jurassic – dino’s ruled the earth for 150
million yrs.
• Cretaceous – leafy trees, shrubs, flying
birds, large reptiles still dominant earth
• Mass extinction (meteor) wipes out half of
all plant and animal groups (including all of
the dino’s)
• Cenozoic Era – animals evolve adaptation
for land, water and air

11. Pattern of Evolution
• 99% of all species that have lived are now
extinct.
• Macroevolution – large scale evolutionary
patterns and processes that occur over long
periods of time
• 6 specific areas of macroevolution – extinction,
adaptive radiation, convergent evolution,
coevolution, punctuated equilibrium, and
changes in developmental genes