Download Scientific Contribution to a Theory of Evolution

Where did we come from??
8.1-Scientific
Contribution to a
Theory of Evolution
SBI3U1
So…Where did we come from?
• This question has been asked for 1000’s of years
• Early ideas based on religion and philosophy suggest that
living things exist unchanged
• 1600’s empirical studies began in Europe
• Observation and experiment to form hypotheses about nature
John Ray (1627-1705)
• One of the 1st scientist to carry
out empirical studies on nature
• Developed classification system
for plants and animal, based on
anatomy and physiology
• Later extended by Carolus
Linnaeus
Georges-Louis Leclerc
(1707 – 1788)
• He challenged the idea that life
forms are unchanging
• He noted the similarities between
humans and apes
• He speculated that Earth was more
than 6000 years
Mary Anning (1799-1847)
• worked as a fossil
hunter and uncovered
the first plesiosaur
• Her work was
confirmed by
Georges Cuvier, the
founder of
“paleontology” (the
study of acient life
through fossils)
Georges Cuvier ( 1769-1832)
• Founder of the field of paleontology (study of fossils)
• discovered that each stratum (layer) of rock held a unique
group of fossil species
• discovered that the oldest fossils are in the deepest layer
• suggested that catastrophes killed many species
(catastrophism) and that these events corresponded to the
boundaries between the fossil strata
Charles Lyell (1797-1875)
• He rejected Cuvier’s
theory of catastrophism
• agreed that Earth was
more than
6000 years old
• He proposed the theory
of uniformitarianism:
geological processes in the
past operate at the same
rate as they do today
• suggested that a slow
and continuous process
could result in substantial
changes in the long term
Jean-Baptiste Lamarck (1744-1829)
• proposed a “line of descent”
progression between current
species and fossil forms
• suggested species increased
in complexity and became
better adapted to their
environment over time
• proposed the idea of the
inheritance of acquired
characteristics whereby
characteristics acquired
during an organism’s lifetime
could be passed on to offspring
Charles Darwin (1809-1882)
• travelled the coast of South
America and made natural &
geographical observations
• used these observations to propose the
“theory of natural selection” -life has
changed and continues to change, due to
natural pressures
Darwin’s Journey with the HMS
Beagle (a british survey ship)
Darwin’s Observations
1. Flora and fauna of the different regions were distinct from
those in Europe.
• Example: rodents in South America were structurally similar to
one another, but different from other continents
Darwin’s Observations Cont’d
2. Fossils of extinct animals looked very similar to living animals
• Example: extinct glyptodont and modern armadillo from South
America
glyptodont
armidillo
Darwin’s Observations Cont’d
3. Finches and other animals Darwin saw on the Galapagos
Islands closely resembled animals he had observed on the
west coast of South America
Darwin’s Observations Cont’d
4. Galapagos species (tortoises and finches) looked identical at
firsrt, but …
• Varied slightly between islands
• Each finch was adapted to eating different type of food
• Different beak size and shape
Darwin’s Observations Cont’d
• 5. Through his experience with artificial selection (breeding
pigeons and studying dogs and flowers) , he knew it was
possible for traits to be passed down from parent to offspring
Theory of Evolution by Natural
Selection…
Survival of the Fittest: organisms that are
the “fittest” leave the most offspring, so
those organisms win the struggle for
survival.
• Their genetic traits are then passed on
to future generations
• Darwin called this “natural selection”
Darwin’s Theory of
Natural Selection
• As written in his book of The Origin of Species
4 ideas summarized
1)Organisms produce more offspring than can survive (leads to
competition for resources)
2)Individuals of a population vary extensively (it is inheritable)
3)Individuals better suited to local condition survive to
reproduce
4)Processes for change are slow and gradual
HOMEWORK
• Make a chart summarizing all the ancient Scientist s theories
and their contribution to evolution. Use this as a study tool for
upcoming quizzes and tests.
• Read 8.1 ( pg. 326-330)
• Complete pg. 331 Q #1, 4, 5, 7, 12