1. Evolution Controversies
19 September 2016

2. Evolution Observation: That life changes through time
Mechanism: Variation, inheritance, selection; Darwin called this ‘natural selection’ or ‘survival of the fittest’
Example: Index fossils. In a narrow layer, from a brief time
Consider ‘pop tops’

3. Evidence for Evolution
Vestigial organs
Intermediate forms, like archeopteryx
Convergent evolution: different history to same point
Even cars evolve, because customers select most appealing characteristics
But cars are designed, can we argue for ‘intelligent design’?

5. Vestigial whale bones

6. Archeopteryx is an intermediate form between reptiles and birds

8. The pot top is an index fossil!

10. Black peppered moth evolved in response to pollution

11. Melanism in British Peppered Moths
Birds are their major predator
They settled on light, lichen-covered trees
In 1848, less than 1% were dark
But industrial revolution pollution killed the lichens, leaving dark trees
In 2000, more than 95% were dark
With pollution laws, now number of light moths increasing
This shows how air pollution drives evolution

12. Rabbits and Myxomatosis
Rabbits are not native to Australia
In 1859, 12 wild European rabbits introduced
By 1886, spreading at 66 mi/year: Reached both coasts by 1907
Nothing could stop the plague of rabbits; fencing, hunting, trapping did not work; they ate grass needed for sheep and cattle
Solution: mosquito-borne virus called myxomatosis : 1952 epidemic killed 99.9%

13. What happened next?

14. What happened next?
Viruses that were less deadly were selected, because their victims could infect others. The deadly ones killed the host, and left no descendants
Rabbits were also selected for greater resistance
Today, mortality is only 40%
All is explained by evolution of both virus and rabbit

15. Convergent evolution of
Mammals and marsupials

16. Evolution of the Corvette

17. Problems for Evolution
Not: Age of Earth, it is 4.5 billion years old. But…
Low probabilities: like a tornado going through a junk yard, leaving behind a 747; small changes to proteins and they don’t work
Gradualism: Gradual changes not seen in the fossil record: long stability, then sudden jump. Can we make a new species gradually?
Complexity: is it irreducible? Examples: human eye, blood clotting requires 12 chemical factors: one missing means hemophilia

18. Replies to evolution questions
Low probabilities: Evolution is not random, selection works only on a useful subset; many other possibilities might work as well, remember convergent evolution on Earth
Gradualism: Fossil record is too poorly preserved; speciation takes longer than a human lifetime; but big random events may be needed
Complexity: Intermediate steps are actually useful; existing genes may be put to new uses; gradually improved; life may be like a Rube Goldberg machine, complicated, but it works

19. Summary Evolution is more than ‘just a theory’
It is an established explanation, universally applied; arguments over details
Creationism is not science: an attempt to use scientific arguments to prove the Bible
Intelligent design is not required: Evolution is like a ‘blind watchmaker’
But problems still: we can’t explain everything yet! Life found elsewhere could provide info