1. Descent With Modification: a Darwinian View of Life
Chapter 22
BCOR 012
February 1, 2010

2. Darwin’s ideas challenged the prevailing view that the world was only a few thousand years old and that each kind of organism had been created individually in six days.

3. In 1645, Bishop Ussher of Ireland stated that the Earth must have been created on October 26th, 4004 BC.

4. Charles Darwin,

5. clergyman and naturalist
Henslow’s sparrow
Reverend John Henslow,
clergyman and naturalist

6. Captain of the H.M.S. Beagle
Robert FitzRoy,
Captain of the H.M.S. Beagle

7. The Voyage of the H.M.S. Beagle

10. Blue-black Grassquit, Volatinia jacarina

11. Darwin’s Beagle Voyage Observations:
Geographic regions have distinctive floras and faunas
Islands are centers of endemism
Organisms are tightly adapted to the conditions under which they live

12. Charles Darwin in 1840

13. Alfred Russell Wallace

14. Charles Lyell, a
geologist, presented the work of both men at a meeting of the Linnaean Society in 1858.

15. 1st printing sold out in a single day!
Darwin in 1859

16. Five premises underlying Darwin’s theory:
Variability: Populations of organisms are variable
Heritability: Some of the variable traits are passed from generation to generation
Overproduction: More individuals are produced in a population than will survive to reproduce
Competition: Individuals compete for limited resources
Differential Survival: Those individuals better suited to their environment will leave more descendents than less well suited individuals.
This is Natural Selection!

17. Evidence Supporting Darwin’s Views ...

18. Homology
The equivalency of structures serving quite different functions
provides evidence of common ancestry.

19. Variation under domestication: an entire array of dogs have been bred from a wolf-like common ancestor.

20. Darwin reasoned that if, under artificial selection, so much change could be produced in a relatively short time, than what a great amount of change should be possible over hundreds of thousands of generations!

21. Two main features of the Darwinian view of life:
The diverse forms of life have arisen by descent with modification from ancestral species
The mechanism of modification has been natural selection operating over immense spans of time

22. Evolution Explains Three Key Observations About Life:
The good “fit” of organisms to their environment (adaptation)
The unity ( shared characteristics ) of life
The diversity of life

23. Charles Darwin,

24. On the Shoulders of Giants - Scientists Who Influenced Darwin

25. Geologist, chemist, naturalist, father of
Hadrian wished to consolidate his boundaries. He visited Britain in 122 AD, and ordered a wall to be
built from west to east "to separate Romans from Barbarians".
JAMES HUTTON
Geologist, chemist, naturalist, father of
modern geology
GRADUALISM
Hadrian’s wall

26. Charles Lyell, Hutton and Lyell’s influence on Darwin:
UNIFORMITARIANISM
Hutton and Lyell’s
influence on Darwin:
The idea that slow
processes operating
over vast periods of
time could produce
great changes.

27. Georges Cuvier ( ) recognized the restriction of distinctive fossils to particular geological series.
Moreover, he observed a pattern in the change from level to level. Of the shells in the upper, more recent levels, he states, " the eye of the most expert naturalist cannot distinguish from those which at present inhabit the ocean." Forms of life recovered from successively more ancient strata were observed to become progressively more strange and "peculiar" (Cuvier 1817:13, ).
G. C. early recognized the phenomena of restriction of distinctive fossils — guide fossils — to particular zones, formations, or series and applied this tool in his stratigraphical studies. Moreover, he observed a pattern in the change from level to level. Of the shells found in the upper, more recent levels, he states that the "eye of the most expert naturalist cannot distinguish from those which at present inhabit the ocean." Forms of life recovered from successively more ancient strata were observed to become progressively more strange and "peculiar" (Cuvier 1817:13, ).

28. Curator at the Natural History
“… Nature has in favorable times, places,
and climates multiplied her first germs of
animality, given place to developments of
their organizations, and increased and
diversified their organs. Then. . . aided by
much time and by a slow but constant
diversity of circumstances, she has
gradually brought about in this respect
the state of things which we now observe.
Text of a lecture given by Lamarck at the
Musée National d'Histoire Naturelle,
Paris, May 1803
Jean Baptiste Lamarck
Curator at the Natural History
Museum in Paris