Download Darwin`s Observations

EARLY THOUGHTS
• Before the idea of evolution, scientist believed that
species had remained unchanged since their creation.
This belief was rooted in religious belief and not
backed by science.
MID-18TH CENTURY IDEAS
• The mid-18th century began booming biologist
trying to classify organisms.
• Carolus Linnaeus came up with the binomial
nomenclature (a 2 part naming system we still
use today)
MID-18TH CENTURY IDEAS
• George-Louis Leclerc spent his life working on a 44
volume natural history series that described all known
plants and animals
• Erasmus Darwin (Darwin’s grandfather) supported
evolution with his writings on changes in animals
during development, animal breeding by humans and
the presence of vestigial structures (anatomical
structures that appear to function in an ancestor but
have long since lost most or all of their functions in
descendants.
LATE 18TH/EARLY 19TH CENTURY IDEAS
• Baron Georges Cuvier- he used comparative anatomy
to develop a system for classifying animals. He also
founded the science of paleontology. He believed
species stay unchanged since creation but as he
studied fossils more, he saw changes in fossils
between the different layers of sediment. This lead to
the idea of catastrophism.
LATE 18TH/EARLY 19TH CENTURY IDEAS
• Jean-Baptiste de Lamarck proposed the idea of acquired
characteristics, where an organisms environment can cause
physical changes that are then passed on to offspring. Ex: A
giraffe’s long neck
• James Hutton suggested the idea that the earth changes over
slow erosion processes and not major catastrophic events. This
helped support the idea that the earth was much older than
originally believed.
• Thomas Malthus was an economist who studied growth and
declines in populations. He proposed the size of the human
population is only limited by the availability of resources. An idea
Darwin applied to this theory later.
DARWIN’S BACKGROUND
• He loved and studied nature from childhood.
• At 16, he was enrolled in Medical School, but did not take to the
study of medicine.
• His father then enrolled him in The School of Divinity at Christ’s
College at Cambridge.
• While there, he befriended John Henslow, a botanist, and Adam
Sedgwick, one of the founders of modern geology.
• He gained many skills in collecting and identifying organisms and
Henslow encouraged him to take a voyage on the HMS Beagle as
their naturalist.
DARWIN’S OBSERVATIONS
• Darwin’s voyage on the HMS Beagle was only suppose to last 2
years, but turned into a 5 year trip, traveling all over the southern
Hemisphere.
• During their stop in present day Argentina, Darwin uncovered
fossils of Glyptodon and Mylodon and found fossils high up in the
Andes Mountains.
Glyptodon (the size of a
small car)
Mylodon- a giant ground sloth
DARWIN’S OBSERVATION
• Darwin also noticed through his travels, that although
the species in the south were different there were
some similarities between the animals of the northern
and southern hemisphere.
Rabbits and the
Patagonian cavy
The Greater
Rhea and The
Lesser Rhea
DARWIN’S OBSERVATIONS
• Most notable among Darwin’s observations are those he made
while on the Galapagos Islands- a small group of volcanic islands
off the coast of South America.
• The islands seemed to have their own type of tortoise, which
varied from island to island.
Tortoise with short necks seemed to inhabit the islands with plenty of
rainfall and ground vegetation. But tortoise with long necks inhabited
the dryer islands with tall cacti for food.
DARWIN’S OBSERVATIONS
•
Darwin also did an intense study of the finches found
on the Galapagos Islands.
•
He concluded that based on where the finch lived (ie:
on the ground or in a tree) and the diet (insects, nuts,
berries) determined the size and shape of the finch’s
beak.
DARWIN’S OBSERVATION
• As Darwin began looking around, he realized that
humans have always been selecting for specific traits
to benefit mankind (artificial selection)
• Examples of this is dog domestication and breeding,
or higher yielding crops
DARWIN’S CONCLUSIONS
• Earth is very old.
• Events observed today must have also happened in
the past.
• Organisms struggle for resources and mates.
• Some organisms are better competitors than others.
• Traits can be selected.
DARWIN’S CONCLUSION
• Darwin reflected on his observations and collected
addition evidence.
• In 1858, with the help of Alfred Russel Wallace, the
two proposed the idea of natural selection.