Lecture 4

1. Lecture 4 Charles Darwin - was he a quack?

2. What is Evolution? • Evolution is technically defined as: "agradual process in which something changes into a different and usually more complex or better form." • As it is most famously used, "evolution" is the process by which an organism becomes more sophisticated over time and in response to its environment. • The Theory of Evolution is currently the most popular concept of how life reached its current state. -Evolution as a biological mechanism is driven by natural selection. • This theory is favored by many scientists to explain phenomena in nature, so much so that it is generally assumed as factual in most studies.

3. Definition • Biological evolution, simply put, is ‘descent with modification’ - C. Darwin. • This definition encompasses • small-scale evolution (changes in gene frequency in a population from one generation to the next) and • large-scale evolution (the descent of different species from a common ancestor over many generations). • Evolution helps us to understand the history of life.

4. Biological Evolution • Biological evolution is not simply a matter of change over time. • Lots of things change over time: • trees lose their leaves • mountain ranges rise and erode, • …but they aren't examples of biological evolution because they don't involve descent through genetic inheritance.

5. The central idea of biological evolution is that all life on Earth shares a common ancestor, just as you and your cousins share a common grandmother.

6. Through the process of descent with modification, the common ancestor of life on Earth gave rise to the fantastic diversity that we see documented in the fossil record and around us today. • Evolution means that we're all distant cousins: humans and oak trees, hummingbirds and whales. • …and slime moulds, and spiders

7. Evolution is a science • Sometimes the best way to understand science is to review the history rather than understand the logic……

8. Very early ideas • Cavemen (75,000 B.C. to 10,000 B.C.) • What could they have pondered over? • Ask the Geico Caveman

9. Early ideas • 550 B.C. • A Greek philosopher, Miletus, argued that the Earth was not created abruptly • life had started as slime in the oceans • later moved to land • humans and other vertebrates had descended from fish.

10. Before Aristotle • 454 B.C. • Another Greek philosopher, Empedocles, speculated that animals developed from plants • The Universe and all in it is gradually changing

11. Aristotle • Aristotle (384 - 322 B.C.) • Suggested that all species are static • All species can be arranged according to the degree of perfection • Created by God • ‘Great Chain of Being’ • These ideas went unchallenged until the 17th century in the Western World

12. John Ray • 1627-1705 • Classified over 18,000 plants • Proposed the first definition of a species • Maintained that species do not change • He was concerned about the fossil record evidence emerging at the time! • He is the ‘Father of Botany’

13. Carl von Linne • Better known by his Latin name - Carolus Linnaeus (1707 - 1778) • In 1735 he tried to classify all life on Earth, in order to discover a pattern of the creation • He wanted to classify ‘Man’ in a group alone but failed to find a scientific reason to do so, and grouped with other apes.

14. Acquired characteristics - Biological evolution is gene based • A regular and sustained program of weightlifting yields enlarged muscles, an immediate physiological response of muscles to the increased effort. However, these big muscles remain with the individual that endured the regular exercises, and are not passed to their offspring. This is because the enlarged characteristics result from individual effort, not from an inheritable genetic change.

15. Evolutionary predecessors • Over the years before Darwin, many biologists attempted to solve the mystery of the “species question.”

16. Who was Charles Darwin?

17. Charles Robert Darwin was born in Shrewsbury, Shropshire, England on 16th Feb 1809 His father (Robert Waring Darwin) and grandfather (E. Darwin) were both doctors His mother was Susannah Wedgewood Darwin was the daughter of a Josiah Wedgewood - founder of Wedgewood China He had one brother and four sisters He attended Shrewsbury Grammar School, but preferred to hunt and collect shells and coins. He also enjoyed learning Latin and Greek.

18. Darwin Family Tree

20. In 1825 he enrolled at Edinburgh University to study medicine, where he learned about taxidermy (useful later in his life) • He dropped out because he did not like the classes. • He had failed his family!! • In 1827 he enrolled at University of Cambridge and began to study to become a clergyman • However, he preferred to collect insects!!! • It was at Cambridge that he began to appreciate the vast diversity of species • His professors were followers of Lamarck’s ideas about inheritance of acquired characters • He also learnt natural theology - Understand God by studying God’s creation

21. Darwin did graduate from Cambridge at age 23 with a B.Sc. Degree in Theology • Before joining the Church of England he wanted to travel - as it was the great time of exploration. • He wanted to visit exotic locations before settling down to religious work. • In 1830, the British government commissioned a 90-foot ship -HMS Beagle - devoted to ‘the acquisition of knowledge.’ It was really to test new clocks and find new sources of wealth. • Darwin, through a contact at Cambridge, was recommended as an alternative and signed up as the ship’s unpaid naturalist

22. The Beagle sailed more than 40,000 miles from Dec 1831 to Oct 1836 • Darwin spent 18 months at sea and the rest of the time on land • Of the 58 month voyage, he spent 43 in South America • He visited the Galapagos Islands where he made his most profound observations. • This time would transform his life and biology!

24. Galápagos tortoise

25. Whilst on the voyage he was given a book to read by the captain - this book would transform Darwin’s thinking • The book was written by Lyell, who had put together all the previous arguments about the age of the Earth and geological time, providing real examples of geological changes that shaped the planet. • When Darwin boarded The Beagle he was a firm believer in the clergy and the fixation of species - when he disembarked he was a changed man and wanted to discover the laws of nature! • Then back on England Darwin began to put all the pieces together….

26. Another book that Darwin read, sealed the deal for him… • A manuscript published by Thomas Malthus implied that given ideal conditions a population would grow exponentially • However, the resources would not grow in the same fashion - they would grow linearly • Therefore, at some time the population would exceed the resources and there would be a ‘struggle for existence’ • Darwin put together the short term struggle for existence (Malthus) with the great geological timescale (Lyell)

27. Galápagos finches • Analysis of these finches led scientists to hypothesize that they were derived from one ancestor arriving from the mainland to populate and diversify across the islands.

29. Evidence supporting evolution • The Fossil record • Common Structures • Species Distribution • Developmental Similarities • DNA sequence comparisons

30. Rock layers • Carbon dating

32. Common Structures • Man • Pig • Horse • Whale • Bat

33. Species Distribution

35. Developmental Similarities

36. DNA sequence comparisons

38. Break

39. Link to the video clips http://www.pbs.org/wgbh/evolution/educators/teachstuds/svideos.html

40. Evolution is not real • Evolution is just a theory! • Watch this clip and answer these questions • http://www.pbs.org/wgbh/evolution/educators/teachstuds/svideos.html • Is a theory just as simple guess? • What is an inference? • What did Darwin infer? 6:06

41. Darwin’s Dilemma • Watch this clip and try to understand the self turmoil which he went through • http://www.pbs.org/wgbh/evolution/educators/teachstuds/svideos.html • Which ship did he travel on? • Which idea became clear to him? • What courage did Darwin have? • Where is he buried? 6:36

42. How does evolution work? • Watch this short video and answer these questions • http://www.pbs.org/wgbh/evolution/educators/teachstuds/svideos.html • Natural Selection is really composed of which components? • How is the length of the humming bird bill determined? 6:41

43. Did humans evolve? • Watch this short video and tackle these questions; • What is a common ancestor? • Is it the same as a chimpanzee? • Which species does not have DNA? • How similar is our DNA to chimps? 5:34

44. Why care about evolution? • Has profound health and welfare issues • Watch and answer these questions • Do bacteria evolve? • How about viruses? • What is the leading infectious killer of adults today? 6:19

45. What is controversial about evolution? • Watch this important clip and digest • What was the evil book? • Must you have to choose between faith and evolution? 6:34

46. Religion and Evolution • The late Pope John Paul II said openly that evolution happened • Many very orthodox people refuse to accept evolution at all • Scientists base their theories on evidence that can be tested - evolution is a very solid theory at this time • Many religious commentators attack single aspects of the evolution theory • It is Religion which cannot be tested in this manner, as we first need evidence to begin

47. Ken Ham • Watch this clip of Ken Ham - a biblical literalist • http://www.pbs.org/wgbh/evolution/library/08/1/real/l_081_04.html • What is his angle on evolution? • What proof does he provide for his views? • How does he explain the finding of fossils? • What is questionable with his interpretation? 6:06