CHAPTER 16: DARWIN’S THEORY
OF EVOLUTION
Section 16-1: Darwin’s Voyage of Discovery
DARWIN’S EPIC JOURNEY
Charles Darwin – born February 12, 1809 in
England
 Scientific view of natural world dramatically
changing

Geologists – Earth ancient, changed over time
 Biologists – life changed

Evolution = change over time
 Darwin developed a scientific theory of
biological evolution that explains how
modern organisms evolved over long
periods of time through descent from
common ancestors.

OBSERVATIONS ABOARD THE BEAGLE

Darwin traveled on the HMS Beagle as naturalist
for 5 years, collecting specimens of plants and
animals from around the world
OBSERVATIONS ABOARD THE BEAGLE
Amazed by the variety/number of living things
 Filled notebooks with observations of
characteristics/habitats
 Noticed three patterns of biological diversity:

Species vary globally
 Species vary locally
 Species vary over time

SPECIES VARY GLOBALLY



Different, yet ecologically similar, animal species
inhabited separated, but ecologically similar,
habitats around the globe
Rheas of South America look/act like ostriches of
Africa, emus of Australia
Live in grasslands – not ALL species the same
SPECIES VARY LOCALLY
Different, yet related,
animal species often
occupied different
habitats within a local
area
 Galapagos Islands –
very close, but very
different conditions
 Tortoises vary in a
predictable way
 BIRDS

SPECIES VARY OVER TIME
Collected fossils – the
preserved
remains/traces of
ancient organisms
 Noticed that some
fossils of extinct
animals were similar
to living species

PUTTING THE PIECES TOGETHER
Darwin analyzed patterns he observed on the
voyage home
 Sent plant/animal specimens to be identified
 Galapagos animals unique, but similar to South
American species
 Evidence suggested species were not fixed –
changed by some natural process
