Unit 2: Evolution
Learning Goal 1: Examine the history of the development of the theory of evolution.
Scientific Theory
A well supported testable explanation of phenomena that have occurred in the natural world.
Charles Darwin (1809-1882)
First attended the University of Edinburgh to become a surgeon.
Transferred to Cambridge to study theology and become an Anglican priest.
Graduated at the age of 22 (1831) and joined the HMS Beagle.
– Father did not want him to join the ship because it might lead him away from a future in the clergy.
– Started as the captains companion and later became the ship’s naturalist.
I have called this principle, by whicheach slight variation, if useful, is preserved,
by the term Natural Selection.
—Charles Darwin from "The Origin of Species"Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.
http://evolution.berkeley.edu/evolibrary/home.php
http://evolution.berkeley.edu/evolibrary/home.php
www.darwinday.org/englishL/life/beagle.htUsed by permission of Darwin Day Celebration (at DarwinDay.org), 2006
www.darwinday.org/englishL/life/beagle.html
http://evolution.berkeley.edu/evolibrary/home.php
Five-Year Voyage
HMS Beagle
Darwin’s Observations
Patterns of Diversity– Darwin observed similar animals that were
diverse in their characteristics.
Darwin’s Observations
Fossils – a large part of the puzzle.– A fossil is preserved remains
of ancient organisms.
Many animals found in
fossils were very similar to
modern day organisms.
Galapagos Islands
Darwin observed that the characteristics of many plants and animals varied noticeably among the different islands.
Galapagos Islands
Each island had a very different climate.– The smallest, lowest islands were hot, dry, and
nearly barren. Sparse vegetation
– Higher islands had greater rainfall. Different assortment of plants and animals.
Island Tortoises
Darwin found that the shape of the shell of the tortoise varied from island to island. – You could use the shape of the shell to determine
where the tortoise had come form.
Galapagos Iguanas
Galapagos Iguanas
The iguanas seemed to adapt to their environments.
Those that lived near trees had feet and claws adapted for climbing in soft tissue.
Those that lived on rocky cliffs had feet and claws adapted to climbing on rocky cliffs.
Darwin’s Finches Darwin found finches around the islands that
had beak types that were specific to the types of food available.
*Those with big thick beaks ate seeds that were available.
*Those with smaller beaks ate the soft flesh of fruit or insects.
Darwin’s Finches
Origin of Evolutionary Thought
Charles Darwin developed the central idea of evolution by natural selection, but others before and during his time also built essential parts of the theory.
James Hutton 1785
Proposes that Earth is shaped by forces that took place over extremely long periods of time.
Proposed Earth to be millions of years old.
Thomas Malthus1798
Human populations will grow faster than the space and food supplies needed to sustain it.
– Competition
Jean-Baptiste Lamarck1809
Publishes his hypothesis of the inheritance of acquired traits.– Ideas were flawed.– The first to propose a
mechanism explaining how organisms change over time.
Charles Lyell1833
Publishes Principles of Geology
Explains that processes occurring now have shaped Earth’s geological features over long periods of time.
Alfred Wallace1858
Independently drew the same
conclusion as Darwin. Evolution by Natural Selection Conferred with Darwin about
ideas.
On the Origin of Species
Published in 1859 Proposed a mechanism
for evolution called Natural Selection– Organisms changed over time as a result of the
change to their environment. – Those best suited for their
environment would survive
and pass on their traits.