7.1 Steps Leading Up To Charles Darwin's Theory Flashcards
What is a theory?
a set of statements that explains a group of facts or phenomenons
Who was the “father” of evolutionary thought?
Charles Darwin
Darwin developed a theory to explain _____?
-The diversity of Life on Earth
-How all organisms are related to one another
-How all organisms are related to the environments
they live in
What is evolution?
the biological history of life on Earth and the process by which organisms change (evolve) over time
Before Darwin’s time, what were the 2 main ideas of the natural world?
1) Species were fixed, did NOT change over time
(immutable)
2) Earth is less than 10, 000 years old (young) and
relatively unchanging
Who decided that living things had been created in their present forms and were immutable?
Aristotle
(he developed this theory through strongly held religious beliefs)
Who was the first to challenge the belief that the earth was young and supported uniformitarianism?
James Hutton
What is uniformitarianism?
a theory that stated that the Earth was formed entirely by slow-moving processes, such as erosion and
sedimentation, and that these slow forces continue to shape the landscape
What did James Hutton conclude from his findings?
Concluded the Earth took millions of years (not thousands), to form the current landscape.
Who was the “father” of Modern Day Geology?
Charles Lyell
What is geology?
the study of Earth’s physical structure
Who Popularized and expanded on Hutton’s idea of uniformitarianism?
Charles Lyell
What are the principles of uniformitarianism?
1) Earth has been changed by the same processes in the past that are occurring in the present
2) Geological change is slow and gradual
3) Natural laws that influence these changes are constant and eternal, and they operated in the past with the same intensity they do today
Why were Lyell’s ideas radical at the time?
Because his theories directly challenged the belief in a very young Earth
What was James Cuvier?
a paleontologist
What is paleontology?
The study of fossil organisms to learn about prehistoric life
What did Cuvier find?
-Compared fossils of modern day elephants to mammoths
-Concluded that some organisms had become extinct over time (e.g. Mammoths, Dinosaurs)
Where can you find the fossils of very simple organisms?
Fossils of very simple organisms are found in ALL depths of fossil deposits
Where can you find the fossils of complex organisms located?
Fossils of more complex organisms are found only at shallower depths, in younger rock
What are fossils in the shallower depths more likely to resemble?
Fossils in the shallower depths are more likely to resemble living species
True or False: Rock layers contain fossils of many species that do not occur in layers above or below them
True
In only which rock can you find fossils?
sedimentary rock
What did fossil observation help us to discover?
Fossil observation offered strong support that life evolved from simple to complex
What is catastrophism?
a theory that global catastrophes, such as floods, caused the widespread extinctions of species
Who believed that species themselves did not change and that these species were then replaced with another newly created set of species
Cuvier
Who applied scientific methods to the detailed study of anatomy and studied animal structures, considering their functions?
Buffon
Who was the “father” of taxonomy?
Carolus Linnaeus
Who proposed that life changed over time?
Linnaeus
Who was Erasmus Darwin?
Charles Darwin’s grandfather
Who suggested that life might have evolved from a single original source?
Erasmus Darwin
Who was a student of Buffon?
Lamarck
Who was the first to offer a mechanism for the evolution of a species?
Lamarck
Who explained evolution as a process of adaptation?
Lamarck
What is adaptation?
An inherited characteristic that improves an organism’s ability to survive and reproduce in an environment
Who was the first to propose a hypothesis to explain how changes in species happen?
Lamarck
What was Lamarck’s first principle?
Use and Disuse
Believed that structures an individual used became larger and stronger while structures that were not used become smaller and weaker
E.g. Ducks strain their toes to swim, and thereby develop webbed feet and penguins’ wings shrink since they don’t use them to fly
What was Lamarck’s second principle?
Inheritance of Acquired Characteristics
Believed that individuals could pass down characteristics they acquired during their lives
E.g. if an adult giraffe stretched its neck during its lifetime, then its offspring would be born with slightly longer necks
What was Lamarck’s third principle?
Tendency Towards Perfection
Organisms continually (willingly) change and acquire features in order to be more successful in their environments
What significant contributions did Lamarck make to our understanding of evolution?
1) All species evolve over time
2) A species evolve in response to its environment and
becomes better adapted to that environment
3) Changes are passed on from generation to
generation
What was the evidence that scientists began to find to contradict a young earth?
fossils
What are fossils?
-preserved remains of organisms
-the closer to the surface, the more recent the ancestor
What are the 3 patterns of diversity that Darwin observed on his voyage?
1) Species vary globally
2) Species vary locally
3) Species vary over time
Describe Darwin’s first observation: species vary globally
-unrelated species look/behave similarly if they occupy similar environments
ex. African ostrich, South American rheas and Australian emus
-some organisms are unique to certain areas
ex. kangaroos
-organisms within a continent (e.g. Australia) can show physical uniqueness when compared to other continents
Describe Darwin’s second observation: species vary locally
-organisms that occupy different habitats, look different
Ex. Galapagos islands
-each island has different climates and there are different turtles on different islands that are adapted to feed differently, depending on available vegetation/geography
Ex. Darwin’s Finches had differently shaped bills according to their feeding patterns
-noticed species on islands looked very similar to species on mainland
Describe Darwin’s third observation: species vary over time
-Studied fossils and noticed patterns
-Some were gigantic versions of modern-day animals such as the armadillo
-Others had no currently living counterparts
-Brought up the question as to “what had happened to cause the extinction of those species?”
Applying Lyell’s ideas, who reasoned that earthquakes gradually lifted rock containing marine fossils from the sea floor?
Darwin
What did Darwin apply the idea of gradual change to?
the evolution of Earth’s life forms
What ideas from geology were important in developing the theory of evolution?
uniformitarianism
-which stated that Earth was formed entirely by slow-moving processes, such as erosion and
sedimentation, and that these slow forces continue to shape the landscape.
-Earth was many millions of years old, and the processes that changed the Earth in the past were the same processes that operate in the present.
How did Lamarck propose that species
evolve?
-he proposed that species evolve, or change, over time
-he explained evolution as a process of adaptation
organisms altered their behavior in response to environmental change
-their changed behavior, in turn, modified their organs, and their offspring inherited those “improved” structures
What parts of Lamarck’s hypotheses have
been proved wrong?
-organisms do NOT have an inborn drive to become more perfect
-evolution does NOT progress in a predetermined direction
-traits acquired by individuals during their lifetime CAN’T be passed on to offspring
What did Lamarck get right?
his most correct assumption was the importance of environmental changes on evolutionary adaptations
What was Malthus’s view of population growth?
-Malthus contended that much of human suffering was due to the human population’s potential to grow
-That is, populations can grow much faster than the rate at which supplies of food and other resources can be produced
-Too many people and too few resources lead to war, disease, and famine
What three patterns did Darwin observe during
his voyage on the HMS Beagle?
-species vary globally
-species vary locally
-species vary over time
How would Lyell explain the formation of the
Grand Canyon?
He would use the uniformitarianism theory and would say that slow-moving processes, such as erosion and
sedimentation shaped the landscape
The rock layers in the Grand Canyon were laid down over millions of years and were then slowly washed away by the river, forming a channel
Suggest how the ideas of a changing Earth and
evolving life forms might be related
-Evolution changes with a changing Earth
-The fact that Earth can change over time inspired the idea that organisms can also change
-Earth’s great age makes it possible for significant changes to have occurred.
Why are Lamarck’s ideas called scientific
hypotheses and not scientific theories?
- A hypothesis is a possible explanation for a set of observations or possible answer to a scientific question
- A theory is a well-tested explanation that unifies a broad range of observations and hypotheses
Suppose a chain of volcanic islands has just
been discovered in the Atlantic ocean, 1000 km
off the west coast of Africa. Each island has a
different climate and terrain. Predict the kinds
of organisms that you might find on the various
islands. Justify your predictions
species vary locally
-organisms that occupy different habitats will look different
-the species on islands will look very similar to species on mainland
A cave salamander is blind. (Its eyes are
non-functional.)
(a) How would Lamarck explain how this
inability evolved from sighted ancestors?
He would say the trait was passed down from its ancestor
-believed that individuals could pass these acquired traits on to their offspring, enabling species to change over time
A cave salamander is blind. (Its eyes are
non-functional.)
(b) Can you think of an alternative explanation?
He also believed that organisms could change during their lifetimes by selectively using or not using various parts of their bodies… since these salamanders lived in caves, they might not have needed to use their eyes.
Suppose a young man works as a construction
worker loading bags of cement onto trucks and
he becomes very strong. If Lamarck’s hypothesis
of use and disuse were correct, would the
man’s offspring also be strong? Explain
The man’s offspring would be strong if they had jobs that required strength and they were using it every day because Lamarck’s hypothesis states that traits an individual uses becomes larger and stronger while traits that are not used become smaller and weaker.
Why is studying islands, such as the Galapagos
Islands, so important in our understanding of
the diversity of life?
-represent the biogeography and climate zones of the world, and therefore demonstrates a high diversity of different phylogenetic lineages from all continents
-islands are also repositories of genetic information whose present-day biodiversity stands as a record of millions of years of evolution
Explain the difference between a theory and a hypothesis.
A hypothesis is an assumption made before any research has been done. It is formed so that it can be tested to see if it might be true.
A theory is a principle formed to explain the things already shown in data.
Describe two or three challenges
scientists encounter while developing
a scientific theory.
1) Make the theory (set of statements that explain a group of facts or phenomena)
2) They have to test it repeatedly and support it with evidence
3) Their theory is just a prediction so it could be wrong and they would have to start the process all over again
Paleontologists have discovered the fossilized
remains of ancestors of whales in Pakistan. These
remains were found far from any large body of
water. What can you infer from this observation?
-whales didn’t always live in water
-they could have had legs and didn’t use them so according to Lamarck’s principle, “use and disuse” and “tendency towards perfection”, they must have not used their legs often, spent more time in water and grew flippers and blubber to adapt to their new environment
-therefore, they could have evolved into aquatic animals
Darwin observed unique species in some
parts of the world. Do you think that modern
travel has affected the distribution of species
around the world? Justify your answer.
?
yes:
-invasive species
-tourism causes endangered species
-tourism damages the environment and animal habitats, forcing species to leave
If an alien species visited Earth to examine
its biodiversity, would they draw the same
conclusions about species distribution as
Darwin did?
?
no:
-species have evolved since then and certain factors have caused species to relocate and leave their habitats
-the concept of “the production of more individuals than the environment can support leads to a struggle
for existence” could be used to explain how some species went extinct, so species distribution isn’t the same as it was
