Lecture 4

Charles Darwin- was he a quack?Charles Darwin- was he a quack?

What is Evolution?Evolution is technically defined as: "a gradual 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.

Definition

Biological evolution, simply put, is Biological evolution, simply put, is ‘descent with modification’ - C. ‘descent with modification’ - C. Darwin.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.

Biological Evolution

Biological evolution is not simply a matter of change over time. Lots of things change over time:

trees lose their leavesmountain ranges rise and erode, …but they aren't examples of biological evolution because they don't involve descent through genetic inheritance.

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

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

Evolution is a science

Sometimes the best way to understand science is to review the history rather than understand the logic……

Very early ideasCavemen (75,000 B.C. to 10,000 B.C.)

What could they have pondered over?Ask the Geico Caveman

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Early ideas

550 B.C. A Greek philosopher, Miletus, argued that the Earth was not created abruptlylife had started as slime in the oceanslater moved to landhumans and other vertebrates had descended from fish.

Before Aristotle

454 B.C.Another Greek philosopher, Empedocles, speculated that animals developed from plantsThe Universe and all in it is gradually changing

Aristotle

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

John Ray

1627-1705Classified over 18,000 plantsProposed the first definition of a speciesMaintained that species do not changeHe was concerned about the fossil record evidence emerging at the time!He is the ‘Father of Botany’

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 creationHe wanted to classify ‘Man’ in a group alone but failed to find a scientific reason to do so, and grouped with other apes.

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.

Acquired characteristics - Biological evolution is gene based

Evolutionary predecessors

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

Who was Charles Darwin?

1. Charles Robert Darwin was born in Shrewsbury, Shropshire, England on 16th Feb 1809

2. His father (Robert Waring Darwin) and grandfather (E. Darwin) were both doctors

3. His mother was Susannah Wedgewood Darwin was the daughter of a Josiah Wedgewood - founder of Wedgewood China

4. He had one brother and four sisters5. He attended Shrewsbury Grammar School, but preferred

to hunt and collect shells and coins. He also enjoyed learning Latin and Greek.

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Darwin Family Tree

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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 clergymanHowever, he preferred to collect insects!!!It was at Cambridge that he began to appreciate the vast diversity

of speciesHis professors were followers of Lamarck’s ideas about

inheritance of acquired charactersHe also learnt natural theology - Understand God by studying

God’s creation

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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

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The The BeagleBeagle sailed more than 40,000 miles from Dec 1831 to Oct sailed more than 40,000 miles from Dec 1831 to Oct 18361836

Darwin spent 18 months at sea and the rest of the time on landDarwin spent 18 months at sea and the rest of the time on land Of the Of the 58 month voyage58 month voyage, he spent 43 in South America, he spent 43 in South America He visited the Galapagos Islands where he made his most profound He visited the Galapagos Islands where he made his most profound

observations.observations. This time would transform his life and biology!This time would transform his life and biology!

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Galápagos tortoise

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….

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)

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.

Evidence supporting evolutionEvidence supporting evolution

The Fossil recordCommon StructuresSpecies DistributionDevelopmental SimilaritiesDNA sequence comparisons

Rock layersCarbon dating

Common Structures

ManPigHorseWhaleBat

Species Distribution

Developmental Similarities

DNA sequence comparisons

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Break

Link to the video clips

http://www.pbs.org/wgbh/evolution/educators/teachstuds/svideos.html

Evolution is not real

Evolution is just a theory!Watch this clip and answer these questionshttp://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

Darwin’s Dilemma

Watch this clip and try to understand the self turmoil which he went throughhttp://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

How does evolution work?

Watch this short video and answer these questionshttp://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

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

Why care about evolution?

Has profound health and welfare issuesWatch and answer these questionsDo bacteria evolve?How about viruses?What is the leading infectious killer of adults today?

6:19

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

Religion and EvolutionThe late Pope John Paul II said openly that evolution happenedMany very orthodox people refuse to accept evolution at allScientists base their theories on evidence that can be tested - evolution is a very solid theory at this timeMany religious commentators attack single aspects of the evolution theoryIt is Religion which cannot be tested in this manner, as we first need evidence to begin

Ken Ham

Watch this clip of Ken Ham - a biblical literalisthttp://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