CHARLES DARWIN
16.1
TARGETS
• State Darwin’s contributions to science
• Identify scientists influencing Darwin & his theory of Natural
Selection
• Explain the role of inherited variation in artificial selection
• Explain Natural Selection using correct terms
• Describe what homologous structures & embryology suggest
about the process of evolutionary change
• Explain how molecular evidence can be used to trace the process
of evolution
YOUNG CHARLES DARWIN
• Born in 1809 in Shrewbury, England
• Studied medicine and ministry in his twenties
• His true interest was nature—he preferred bird-watching
and reading for fun instead of studying
• He left home at 16 to attend Edinburgh University and
study medicine. Later enrolled in Cambridge to prepare
for a career as a clergyman.
• Encouraged by his Cambridge professor to take a job as a
naturalist
DARWIN’S TRAVELS
• Upon receiving his degrees, Darwin accepted an invitation to serve
as an unpaid naturalist on a five-year expedition to South America
aboard the HMS Beagle
• On this voyage, he studied differences within the land and also
collected fossils
• This voyage, along with his later research, formed the basis for his
theory of evolution by means of natural selection
• This is detailed in his book On the Origin of Species, which was published
in 1859
3 DISTINCTIVE PATTERNS OF BIOLOGICAL DIVERSITY
• During his travels, Darwin noticed these 3 patterns:
• 1. Species vary globally
• 2. Species vary locally
• 3. Species vary over time
GLOBAL DIFFERENCES
• Flightless birds were seen in the grasslands of South America,
Africa, and Australia, although they were different birds.
• Rheas lived in the grasslands of South America
• Ostriches lived in Africa
• Emus live in Australia
• Although living in different places, the birds had strong similarities:
flightless and ground-dwelling
LOCAL DIFFERENCES
• Rheas were found living in Argentina’s grasslands, but also
in the cold, harsh scrubland to the south.
• Darwin noticed that different, yet related animal species
often occupied different habitats within a local area
• Other examples came from the Galapagos Islands
GALAPAGOS ISLANDS
• Located about 600 miles west of South America
• As a naturalist, Darwin collected species with great care
and interest
DARWIN’S FINCHES
• While on the Galapagos Islands,
Darwin found 13 species of
finches
• This lead to his idea of descent
from a common ancestor
EVOLUTION
• Evolution – the process of 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
DARWIN’S THEORY OF NATURAL SELECTION
• Tendency towards overproduction
• Not all offspring survive
• Variations exist in any population
• Variations are inherited
• The best organism will live longer and produce more
offspring
• Populations change as it becomes better adapted to its
environment
ORIGIN OF SPECIES BY NATURAL SELECTION
• Written in 1844
• Published in 1859
• Darwin continued throughout most of the rest of his life
to publish his research and writings on biology
• In his later years, Darwin was plagued by fatigue and
intestinal sickness, thought by some historians to have
been caused by Chagas’ disease, contracted during his
travels in South America.
• Also called American trypanosomiasis (tri-PAN-o-SO-mya-sis), Chagas disease is an infection caused by the
parasite Trypanosoma cruzi. It is estimated that 16-18
million people are infected with Chagas disease; of those
infected, 50,000 will die each year.
CHARLES DARWIN
• Charles Darwin died on April 19,
1882, and lies buried in
Westminster Abbey
ISN’T EVOLUTION JUST A THEORY?
• In science, a theory is a rigorously tested statement of general
principles that explains observable and recorded aspects of the
world. A scientific theory therefore describes a higher level of
understanding that ties "facts" together. A scientific theory stands
until proven wrong -- it is never proven correct. The Darwinian
theory of evolution has withstood the test of time and thousands
of scientific experiments; nothing has disproved it since Darwin
first proposed it more than 150 years ago. Indeed, many scientific
advances, in a range of scientific disciplines including physics,
geology, chemistry, and molecular biology, have supported,
refined, and expanded evolutionary theory far beyond anything
Darwin could have imagined.”
INFLUENTIAL SCIENTISTS
• Darwin’s Cambridge Professor
• Charles Lyell, a contemporary geologist
• Wrote Principles of Geology
• Jean Lamarck, proposed theory of evolution in 1801
• Alfred Wallace, made similar observations and conclusions
about the process behind evolution shortly before Darwin
published his book