2.2mya A Boisei

The Evolution of SpeciesThe Evolution of Species

The Three Es Approach:

• ExplanationExplanation – clear, thorough, and with an explicit acknowledgment of the limits of a theory’s explanatory power

• EpistemologyEpistemology – how do we know what we “know”? Who are the people that have devoted their lives to studying evolution?

• EmpathyEmpathy – recognize that many people have deep religious convictions that inhibit objective learning. You will never gain the skeptic’s ear if you fail to recognize and/or refuse to appreciate this fact.

According to recent polls:

*76% of Americans believe in the biblical account of creation

*79% that miracles in Bible took place

*76% believe in angels, the devil and other immaterial souls

*67% believe they will exist in some form after their death

*15% believe that Darwin’s theory of evolution is the best explanation for the origin of human life on earth.

Strong support for creationism

• Most Americans believe in some form of creationism, according to a CBS poll conducted ahead of last November’s election. Fifty-five percent of Americans believed God created humans in their present form, and a further 27 percent believed humans evolved, but God guided the process.

• Sixty-five percent of all Americans favored schools teaching creationism and evolution, while 37 percent wanted creationism taught instead of evolution.

• The poll found greater support for teaching creationism among Republican voters — 71 percent of Bush voters favored teaching creationism alongside evolution.

Intelligent Design?

• According to the National Council for Science Education, a pro-evolution group in Oakland, California, other states considering legislation on the issue include Georgia, South Carolina, Mississippi, Montana, Oklahoma, Alabama and Texas. Other state or local school boards debating the teaching of intelligent design include Ohio, Arkansas, Wisconsin, Kansas, Wisconsin, Maryland, Michigan, Tennessee and Alaska.

“… evolution is a theory. It is also a fact. And facts and theories are different things, not rungs in a hierarchy of increasing certainty. Facts are the world's data. Theories are structures of ideas that explain and interpret facts. Facts do not go away when scientists debate rival theories to explain them. Einstein's theory of gravitation replaced Newton's, but apples did not suspend themselves in mid-air, pending the outcome. And humans evolved from apelike ancestors whether they did so by Darwin's proposed mechanism or by some other, yet to be discovered.”

Stephen Jay Gould, "Evolution as Fact and Theory," 1981

A brief history of evolutionary theory

Charles Darwin 1809-1882

The Beagle 1831-1836

Galápaos Isles

• “when comparing…the birds from the separate islands…both with one another and with those from the American mainland, I was much struck how entirely vague and arbitrary is the distinction between species and varieties”

Alfred Russell Wallace

• “On the Tendency of Varieties to Depart Indefinitely from the Original Type”

• 1858 – Wallace and Darwin theories of natural selection presented to Linnean Society of London

Carolus Linnaeus, Systema Naturae (1758)

Jean Baptiste (le Marquis) de Lamarck

Philosophie Zoologique (1809)

Charles Lyell

1830 Lyell publishes Principles of Geology, establishing the earth’s antiquity

Gregor Mendel (1822-1884).• Mendel’s theories of

heredity • based on his work with

pea plants, GM identifies inheritance and mutation as a source of change.

• These ideas are not appreciated until the early 20th century

Mendel’s Principle of Principle of SegregationSegregation – principle of

inheritance

Characteristic Dominant Trait Recessive Trait 1 Form of ripe seed Smooth Wrinkled 2 Color of seed albumen Yellow Green 3 Color of seed coat Gray White 4 Form of ripe pods Inflated Constricted 5 Color of unripe pods Green Yellow 6 Position of flowers Axial Terminal 7 Length of stem Tall Dwarf

The Modern Synthesis

• Mendel’s ideas about genes and heredity combines with Darwin’s ideas about natural selection.

• Mutation and the recombination of genes provide for genetic variety

• After years of hard work and effort Watson and Crick propose their idea of the double-helical structure for DNA in 1953.

•Along with Wilkins, W&C win the Nobel prize for their work in genetics in 1962

• Biological Mechanisms that drive Human Evolution

• VariationVariation-- Inherited (i.e. genetically influenced) difference between individuals.

• Allele frequencyAllele frequency – The proportion of one allele to all alleles at a given locus in a population.

• Gene FlowGene Flow – The exchange of genes/alleles between “populations”; usually through migration.

• Genetic DriftGenetic Drift – Changes in allele frequencies produced by random factors. Entails a small population size.

• MicroevolutionMicroevolution – Small-scale evolutionary changes that occur over the span of a few generations and can therefore be detected in living populations. I.e. Macro comes thru micro.

• MacroevolutionMacroevolution – Large scale evolutionary changes (esp. speciation events) that may require many hundreds of generations and are usually only detectable in the fossil record, i.e. in the long term (paleontologically).

• PopulationPopulation – group of interbreeding individuals, marked by genetic relatedness; members share a common gene pool.

• Breeding isolatesBreeding isolates – largest factor is geography and ecology; social factors are also huge (i.e. endogamy/exogamy practices).

• The driving force of change is generally understood to be adaptation to environments through natural selection

• SpeciationSpeciation: the development and divergence of different species

• Natural SelectionNatural Selection – The differential reproductive success of certain phenotypes (and their underlying genotypes)

Natural SelectionNatural Selection requires three conditions

• Variation

• Heritability, or mechanisms that duplicate traits in offspring

• Differential reproduction because of heritable differences

Natural Selection in action

• Peter Grant: In 1977, he returns to the Galápagos to study the same finch populations as Darwin.

• Using colored bands they track the birds during a serious drought (i.e. environmental change).

• Over 18 months, 85% of adult finches disappeared.• Those that survived were all larger and with larger

beaks.• Conclusions:

– drought conditions favor bigger beaks (better for cracking husks of large seeds).

– Estimates that 20 such episodes of drought would lead to speciation

• Gene frequencies of a population, it was commonly believed, changed slowly and gradually as adaptive traits increased in prevalence and maladaptive traits decreased….

• When this process is combined with populations, usually through isolation, encounter different environmental conditions

• (thus different traits will be selected for/against

Punctuated equilibrium: Punctuated equilibrium:

• Gould and Eldridge 1972• Challenges the view that change is slow and

gradual, positing instead “fits and starts”• A species is born abruptly, changes little during

its career, and then becomes extinct.• Still following principle of natural selection, but,

“the succession of one species after another involves replacement from outside more often than gradual change over time” (EEP 2002:36).

Natural Selection in action

• Peter Grant: In 1977, he returns to the Galápagos to study the same finch populations as Darwin.

• Using colored bands they track the birds during a serious drought (i.e. environmental change).

• Over 18 months, 85% of adult finches disappeared.• Those that survived were all larger and with larger

beaks.• Conclusions:

– drought conditions favor bigger beaks (better for cracking husks of large seeds).

– Estimates that 20 such episodes of drought would lead to speciation

Neo Darwinian Theory

• The birth of modern genetics only served to support what Darwin had suspected, with no such knowledge

“If the Darwinian theory is true, Genesis is a lie”

• 1859 – Origin of Species is published

•Darwin’s Dangerous Idea ?Daniel Dennet

“If the Darwinian theory is true, Genesis is a lie”

So what are we afraid of??

Stephen Jay Gould (1941-2002)

• "Humans are not the end result of predictable evolutionary progress, but rather a fortuitous cosmic afterthought, a tiny little twig on the enormously arborescent bush of life, which if replanted from seed, would almost surely not grow this twig again." - Stephen Jay Gould

• Gould and Eldridge 1970’s

• “Punctuated Equlibrium”• Explains the apparent

lack of intermediate forms

SJG Appears on the Simpsons in “Lisa the Skeptic”

A brief history of the controversy

The Scopes Trial

• May 2005: In Kansas, three daylong hearings, referred to as a direct descendant of the 1925 Scopes Monkey Trial in Tennessee, Darwinism goes on trial once more.

John T. Scopes 1925

• Rhea County Courthouse in Dayton, Tenn., as it appeared in 1925 at the time of the Scopes trial. Bryan College Archives

Clarence Darrow and William Jennings Bryan, 1925 Clarence Darrow, a famous Chicago lawyer, and William Jennings

Bryan, defender of Fundamentalism, have a friendly chat in a courtroom during the Scopes evolution trial. Darrow defended John T. Scopes, a

biology teacher, who decided to test the new Tenessee law banning the teaching of evolution. Bryan took the stand for the prosecution as a bible

expert. The trial in 1925 ended in conviction of Scopes

• The Scopes "Monkey" Trial, 1925 The Scopes "Monkey" Trial was a court case in Tennessee involving the teaching of evolution in public schools.

• In March of 1925 the State of Tennessee passed a statute was that prohibited the teaching in public schools of theories contrary to accepted interpretation of the biblical account of human creation.

• John T. Scopes, a biology teacher, was tried in July, 1925 for teaching Darwinism in a Dayton, Tennessee public school.

• Darrow argued that academic freedom was being violated and claimed that the legislature had indicated a religious preference, violating the separation of church and state.

• He also maintained that the evolutionary theory and certain interpretations of the Bible were not mutually exclusive.

• In an especially dramatic session he sharply questioned Bryan on the bible's literal interpretation

• There was a circus atmosphere that summer, literally, with the media and public focus on Dayton, complete with performing monkeys and street corner ministers.

• July 20, 1925 was an extremely hot Monday afternoon, so Judge Raulston moved the court proceedings outdoors.

Journalist H.L. Mencken dubbed Dayton "monkeytown."

• Joe Mendi.

A reporter’s memo at the start of the trial

Triumphalism:But does it lead to arrogance?

Humans are Primates

• In the wake of the 1999 Columbine shootings, Tom Delay (Majority Whip, Reps) said that this type of violence is inevitable as long as “our school systems teach children that they are nothing but glorified apes, evolutionized out of some primordial soup of mud.”

Primatologist, Jane Goodall

• Primitive – Refers to a trait or groups of traits present in an ancestral form

– compared to other mammals, primates have retained many of these primitive, or

• Generalized, traits. We must therefore speak of a group or traits when defining this group.

• Specialized – Evolved for a specific function; specific trait (e.g. incisor teeth; opposable thumb).

Classification of Living Primates

How do we differ from our nearest primate relatives??

Evolutionary classification: clavicle

Hadrocodium Wui

Radiation and Adaptation

Do the Locomotion…

Human Dentition

Stereoscopic Vision

Quadropedalism

The first neanderthal fossil, discovered 1856 near

Dusseldorf

L.. KNM-ER 1470

(H.Rudolphensis

C. KNM-ER 3733

(H.Ergaster

R., KNM 406

(P.Boisei