Transcript a lecture on the development of Darwins` ideas

Dangerous ideas: Evolution
Jeremy Pritchard
School of Biosciences
Cratægus oxycantha.—A dark pink hawthorn has been known to throw out a
single tuft of pure white blossoms;18
Mr. A. Clapham, nurseryman, of Bradford, informs me that his father
had a deep crimson thorn grafted on a white thorn, which, during several
years, always bore, high above the graft, bunches of white, pink, and deep
crimson flowers.
Hillside Court, Ilkley
White Wells Bath House, Ilkley Moor
Darwin was staying in Ilkley and taking water cure treatments when
‘On the Origin of Species…’ was published in November 1859
http://www.biosciences.bham.ac.uk/links/teachers/teachers.htm
Darwin’s theory of evolution
o
o
o
o
o
Many are born
Individuals vary
Not all survive
‘Useful’ variations increase
Variations are inherited
Diversity is the consequence of the non-random
survival of randomly varying replicators
1. Random
= Mutation
2. Non random
= Natural selection
3. Replicators
= Inheritance
Evolution was one of the first Darwin
beers produced.
The strange thing was that a mistake was
made on the original recipe
-yet the resulting beer was (and still is)
better than we could have imagined..
-hence the beer evolved into one of our
best sellers.
60
Biology
50
English
Engineering
40
# students
30
20
10
0
0
1
Support evolution
2
3
4
5
6
Don’t support Evolution
Subject specific views of evolution:
2nd year students University of Birmingham, Autumn 2007
Young Earth Creationism is the idea that God created the
world sometime in the last 10,000 years.
In your opinion is Young Earth Creationism…
40
60
50
30
40
20
30
20
10
10
0
0
Definitely
true?
Probably
true?
Probably
untrue?
Definitely
untrue?
Don't know?
True
False
“The diversity of organisms, similarities and differences
between kinds of organisms, patterns of distribution and
behaviour, adaptation and interaction, all this was merely
a bewildering chaos of facts until given meaning by the
evolutionary theory.”
Mayr
“Science simply cannot … adjudicate the issue of God’s
possible superintendence of nature. We neither affirm nor
deny it; we simply can’t comment on it as scientists.”
Gould
The issues
o Organising diversity - trees
o Evolution as ‘dangerous’
o Design and complexity from chance
o Science and intelligent design
10s of years
100s of years
1000s of years
Millions of years
There is a lot of diversity out there…
Where does it come from?
Organising diversity:
Taxonomy and trees
So…..
What’s the reason some things are more similar than others?
Descent with modification from a common ancestor
What’s the mechanism?
Natural selection
The issues
o Organising diversity - trees
o Evolution as ‘dangerous’
o Design and complexity from chance
o Science and intelligent design
Change…
o Fact ?
o Mechanism ?
The Great Chain of Being
• Ideas of organisation
and direction in evolution
• Complex is better
The middle ages
• Change is dangerous…
AL-BIRUNI 973 - 1048
• Gradual changes
• But change is dangerous…
Change…?
Stasis!!
Classification - Linneaus
• Species descriptions
• But some things are more similar than others...
Explaining complexity
Intelligent design
• Explaining complexity
Irreducible Complexity = Intelligent design
Michael J. Behe
Is Intelligent Design a Science?
The emergence of change
Stasis ?
…Change
Voyages of discovery
Wedgwood
• Small changes improve things
• Experiments are needed
Erasmus Darwin
But change is dangerous…
Stasis ?.... Change!
Mechanism?
Lamark
• Inheritance of acquired
characteristics
• Desire to improve
Charles Darwin
Malthus: An Essay on the Principle of Population
Noted
1. Overproduction of young
2. Rising population outstrips resources
3. Lower classes are irresponsible.
Solution
Family size of the lower class regulated so that
they do not produce more children than they
can support
Replacement of religion ?
Who trusted God was love indeed
And love Creation’s final law–
Tho’ Nature, red in tooth and claw
With ravine, shriek’d against his creed–
Replacement of religion?
o Evolution explains mechanism
o It does not explain purpose
o Ask What? and How?
o Be careful with Why?
Are we still evolving?
Microevolution: change in gene frequency - YES
Macro evolution: formation of species - NO
Are we still evolving?
• Some parts of Africa have seen an increase in the
frequency of a gene called CCR5-32
• Protects against infection with HIV-1.
• May have been selected for during bubonic plague
Human
Chimp
H. erectus
H. habilis
A. afarensis
Monkey ancestor
Australopithecus afarensis
Lucy, 3 mya
Two legs good,
four legs bad?
Humans are not top of the tree …
• Bad back
• Flat feet
• Varicose veins
• Heart disease
• Piles
http://www.biosciences.bham.ac.uk/links/teachers/teachers.htm
http://www.biosciences.bham.ac.uk/links/teachers/teachers.htm
1.A Historical perspective: One strategy for confronting creationist’s views is to take a historical
perspective. Explaining how the theory of evolution by natural selection developed allows the teacher to
take a more less
2.Human Evolution: A practical that explores human bipedalism and larger brain size. Measurements
are performed on hominid fossil material and the students themselves. The necessary pictures needed to
do the exercise can be downloaded.
3.Taxonomy: Phylogenetic trees provide a powerful image/metaphor to explain some important
evolutionary concepts. Students choose phenotypic characters for a range of organisms and these are fed
into a computer programme reveals the similarities and differences between the organisms. The practical
can be delivered in a variety of ways, from the class room through to zoo visits.
4. Evolution in action: Variation, mutation and selection in plants: An experiment that demonstrates
some of the components of evolution. Arabidopsis plants are grown in the presence or absence of sodium
chloride and measurements of rate of development demonstrate both variation and the selective effect of
stress.
5. Evolution of complexity: Evolution theory is often critisised for being unable to explain how chance
can generate complex organs such as the eye. However Natural selection is a combination of random
mutation and non-random differential survival. An 'Excel' exercise to demonstrate how complexity can be
rapidly produced by chance plus selection is available.
6. Dealing directly with Creationist arguments: A creationist document arguing that plants cannot
have evolved by Darwinian evolution has been annotated with over 80 the counter arguments and can
accessed online.