06. Evolution

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“Evolve” Means to Change Over Time

The belief that life on Earth has changed overtime is quite old

To be considered science, this belief requiresa great deal of evidence

http://www.nap.edu/readingroom/books/evolution98/page8.html

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The Development of Evolutionary Theory

Naturalists have always wondered at thediversity of living things……… Great varieties in shape, size, and ecological role

Estimated 3 million to 20 million different livingspecies

Much of the natural world’s biodiversity has vanishedthrough extinction

99% of all species that ever lived are now extinctPermian-Triassic Mass Extinction

What Killed the Dinosaurs?

http://localhost/var/www/apps/conversion/tmp/scratch_2/Extinction.mov

http://localhost/var/www/apps/conversion/tmp/scratch_2/Premian-Triassic%20Extinction.mov

http://www.pbs.org/wgbh/evolution/extinction/dinosaurs/index.html

http://www.pbs.org/wgbh/evolution/extinction/dinosaurs/index.html




http://localhost/var/www/apps/conversion/tmp/scratch_2/Extinction.mov

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What Killed The DinosaursOne of the greatest puzzles inpaleontology.

Dinosaurs dominated the Earth for morethan 150 million years.

Dinosaurs vanished from the Earth 65million years ago.

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What Killed The DinosaursScientists have looked beyond fossils inthe search for answers to what killedthe dinosaurs.

Geological evidence holds clues and hascontributed to many hypotheses:working explanations of how dinosaursmay have become extinct.

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What Killed The Dinosaurs

Asteroid ImpactDid a collision with a giant asteroid or cometchange the shape of life on Earth forever?

It is widely agreed that such an object – 10 kmacross – struck just off the coast of the Yucatanpeninsula 65 million years ago.

According to scientists who maintain thatdinosaur extinction came quickly, the impactmust have spelled the cataclysmic end.

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Asteroid ImpactScientists have discovered levels of iridium 30times greater than average in the

Cretaceous/Tertiary (KT) boundary, the layer of sedimentary rock laid down at the time of thedinosaur extinction.

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Melted Rock & Asteroid ImpactRanging in size from large chunks to tinybeads, these pieces of melted granite are

common at or near the Cretaceous/Tertiary(KT) boundary, the geological layer that definesthe dinosaur

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Melted Rock & Asteroid Impact65 million years ago, the 10-km wide asteroidapproaches the Earth.

The asteroid strikes with a force of 300 millionatomic bomb blasts.

Earth’s atmosphere fills with dust and gas from

the impact and smoke from forest fires.Starved of sunlight for months, the majority of life on Eath perishes.

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Fractured Crystals & Asteroid ImpactSome scientists maintain that the fracturepattern in these quartz crystals could only have

been caused by a massive asteroid or comectimpact. The pattern is prevalent in quartz foundat or near the Cretaceous-Tertiary (KT)boundary, the geological layer deposited at the

time of the extinction.

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Fossil Record & Asteroid ImpactSome paleontologists see evidence in the fossilrecord that dinosaurs were doing quiet well

prior to the end of the Cretaceous – that theywere in no way declining in abundance whenthe impact occurred.

Cretaceous: The final geological period of theMesozoic era that began 144 million years agoand ended 65 million years ago. The end of thisperiod is defined most notably by the extinction

of the dinosaurs in one of the largest mass

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Impact Crater & Asteroid ImpactScientists have concluded that the impact thatcreated the crater occurred 65 million years

ago. The date corresponds perfectly to the dateof the dinosaur extinction.

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Melted Rock These pieces of once-molten rock, calledimpact ejecta, are evidence of an explosion

powerful enough to instantly melt bedrock andpropel it more than a hundred miles from itsorigin.

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Fractured CrystalsThese crystals

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Melted Rock These pieces of once-molten rock, calledimpact ejecta, are evidence of an explosion

powerful enough to instantly melt bedrock andpropel it more than a hundred miles from itsorigin.

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Melted Rock These pieces of once-molten rock, calledimpact ejecta, are evidence of an explosionpowerful enough to instantly melt bedrock andpropel it more than a hundred miles from itsorigin.

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Development of Evolutionary Theory

What could cause such great diversity, andwhy have so many species died out?

Charles Darwin offered an explanation based oncareful observations

Who was Charles Darwin?

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Development of Evolutionary Theory

Darwin Concluded:

Physical traits and behaviors enable organisms

to survive and reproduce (called Fitness )Fitness results from adaptations

Darwin reasoned that adaptations result from

natural selection and result in evolution

Evolution is the process by which living thingschange and diversify over time

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Development of Evolutionary TheoryThese ideas were widely challengeduntil a tremendous amount of evidencewas gathered to support evolution!

Now…The Theory of Evolution is theCornerstone of Biology

Explore the Evolution Revolution

http://www.pbs.org/wgbh/evolution/religion/revolution/index.html

http://www.nap.edu/readingroom/books/evolution98/page55.html

http://www.pbs.org/wgbh/evolution/religion/revolution/index.html

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http://www.lhl.lib.mo.us/pubserv/hos/dino/images/owe4h.jpg

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The Origin of Life

Geology

The Fossil Record

Comparative EmbryologyComparative Biochemistry

Comparative Anatomy

Isn’t Evolution Just a Theory?

Scientists from many disciplines includingbiology, chemistry, physics, geology, andpaleontology have contributed to the casefor evolution!

http://www.pbs.org/wgbh/evolution/library/11/2/e_s_1.html


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The Origin of LifeOrigin of the Universe

Big Bang

Early EarthEvolution Starts Up: Chemical Evolution

Heterotroph Hypothesis: Molecules of life

arose from inorganic building blocks

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The Miller-Urey Experiment Studied Molecules Present at Time of Early Earth

Methane, Ammonia, Carbon Dioxide,

Water VaporMixed Molecules in Reaction Chamber

Sparked with Electricity to SimulateLightning

Exposed Mixture to UV Radiation toSimulate Cosmic Rays

Produced Basic Amino Acids and OrganicMolecules

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Miller-Urey Apparatus

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Biological EvolutionRNA as a information molecule andcatalyst

Endosymbiotic Theory

Mitochondria and chloroplasts wereoriginally free living prokaryotic cells

Both have own DNA and ribosomes

Joined together to cooperate

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GeologyThe Study of the Earth and Rocks

Early Ideas About Earth:

People believed Earth was only a fewthousand years old

People believed that rocks and geological

features were shaped by catastrophicevents and rarely changed

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GeologyIn the 18th and 19th Century ScientistsStudied Geology in Great Detail

Over millions of years 1 original continent Pangea

drifted apart to make our modern continents

Continental drift is gradual “gradualism”

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Geology

Hutton and Lyell:Earth is Changed

by Weather andNatural Processeslike Volcanoesand Erosion

Takes a Very LongTime!

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GeologyThese ideas refute the idea that the Earth isonly a few thousand years old

Backed up by radiometric dating

The Earth is approximately 4.6 Billion Years Old

4,600,000,000 years is a long time!

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The Fossil Record

Fossils are the preserved remains of ancient organisms

Provide information about past

organismsShows that many diverse organismslived at different times in Earth’sHistory

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The Fossil Record

Taphonomy: The Formation of Fossils

Fossils form in sedimentary rock

Dead organisms covered by sand and siltSediments are passed into bone bypressure from above (fossils form in

sedimentary rock) Video

http://www.pbs.org/wgbh/evolution/library/04/3/l_043_01.html


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Determining the Age of Fossils

Relative Dating: Technique used byscientists to determine the age of fossils

relative to fossils in other layers of rock Different layers represent different geologicperiods

Older fossils found in lower layers, newerfossils found in upper layersCannot determine the actual age of thefossil!

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Determining the Age of FossilsRadioactive Dating: Process by which traces of radioactive elements are analyzed to calculate theactual age of a fossil

Many radioactive elements can be used as geologicclocks. Each radioactive element decays at its ownnearly constant rate. Once this rate is known,geologists can estimate the length of time over

which decay has been occurring by measuring theamount of radioactive parent element and theamount of stable daughter elements

Video



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Radiometric Dating Radioactive

Parent

Stable

DaughterHalf life

Potassium 40 Argon 401.25 billion

yrs

Rubidium 87 Strontium87 48.8 billionyrs

Thorium 232 Lead 20814 billion

years

Uranium 235 Lead 207704 million

years

Uranium 238 Lead 206 4.47 billionyears

Carbon 14 Nitrogen 14 5730 years

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The Geologic Time ScaleBased on fossil and geologic evidence

A record of the Earth’s past

Divided into Era, Period, and EpochShows that life on Earth followed geologicchange on Earth

Deep Time Activity

Interactive Time Scale

http://www.pbs.org/wgbh/evolution/change/deeptime/index.html

http://www.pbs.org/wgbh/nova/link/history.html

http://www.enchantedlearning.com/subjects/Geologictime.html

http://www.pbs.org/wgbh/nova/link/history.html

http://www.pbs.org/wgbh/evolution/change/deeptime/index.html

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Comparative EmbryologyEmbryos are organisms at early stagesof development

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Comparative Embryology

All vertebrate embryos,including humans, sharefeatures

Eye spot• (Evolution of the Human Eye)

Gill pouches

Notochord

Shows similar geneticancestry

Video





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Comparative Biochemistry

All life is based on organic chemistry

Carbon based compounds

All life uses same molecule as blueprintDNA

Similar chemical processes

Bacteria, algae, and plants all do photosynthesisSimilar organisms have similar genetic code

Humans and chimpanzees share nearly identical

genes (98.4% identical gene sequences) Video



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Anatomy and Comparative Anatomy Vestigial Organs

Organs inherited but not used by modern

organismsPresent but greatly reduced in modernorganisms

Hip bone in python

Appendix in human

Tail bone (cocyx) in human

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Anatomy: Homologous StructuresSimilar parts of different organisms,often quite dissimilar in purpose, that

developed from the same ancestralbody parts (Video)

Divergent evolution



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Anatomy: Analogous StructuresSimilar in purpose, but not inheritedfrom a recent common ancestor

Environment selected for trait

Wings of birds and insects

Convergent evolution

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SummaryThere is overwhelming evidence tosupport the Theory of Evolution

Evidence comes from disciplines asvaried as biology, geology, chemistry,physics, astronomy, and paleontology

Evolution has produced the greatbeauty and diversity of life on Earthover the last 4 billion years

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Natural Selection

and Speciation

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Charles Darwin

Studied Medicine and Theology

Excelled in Geology and BiologyIn 1831 Darwin joined the H.M.S.Beagle on a trip around the world to

make mapsHe was the ship’s naturalist

Darwin’s Diary

http://www.pbs.org/wgbh/evolution/darwin/diary/index.html

http://www.pbs.org/wgbh/evolution/darwin/diary/index.html

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The Voyage of the Beagle: Ports of Call

Noted that populations of organisms were slightlydifferent from place to place

Each group was modified to their specific environment

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The Galapagos Archipelago

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Land Iguana

Marine Iguana

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The Origin of Species Interactive Exploration

http://www.pbs.org/wgbh/evolution/darwin/origin/index.html


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Evolution Through Natural Selection

There is variation in populations caused bygenetics (Praying Mantis Camouflage)

Many more offspring are produced than cansurvive. Many die through predation or starvation

Some variations are favorable and helporganisms compete to survive and reproduce

Over time, the organisms with favorablevariations become plentiful. The ones withoutfavorable variations become rare or extinct

Reluctantly published On the Origin of Species in1859

Video


http://www.pbs.org/wgbh/evolution/library/02/2/quicktime/l_022_04.html



http://www.pbs.org/wgbh/evolution/library/02/2/quicktime/l_022_04.html


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SpeciationNatural Selection modifies populations.Some evolutionary changes are so great

that some organisms can no longerinterbreed with the original population

A new species results

Species An interbreeding population of organismsthat can produce healthy, fertile offspring

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Reproductive Barriers and Speciation

Prezygotic: gametes never meet and fuse

Geographic isolation (allopatric speciation)

Ecological isolation

Behavioral isolation (lacewing songs) Mechanical isolation

Seasonal isolation

Postzygotic: genetic differences manifest

Hybrid inviability

Hybrid sterility (tigons and ligers)







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Patterns in Evolution

Adaptive Radiation

Development of numerous new species from acommon ancestor in diverse environments

Darwin’s Finches (Origin of Species Activity)

Gradualism

Punctuated Equilibrium



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Evolution Produces Diversity

All living things are classified by characteristicsinto 5 kingdoms of life

Monera: bacteria, unicellular prokaryotes

Protista: single celled eukaryotes

Fungi: multicellular, eukaryotic, nonmotile, heterotrophs

Plantae: multicellular, eukaryotic, autotrophs Animalia: multicellular, eukaryotic, motile, heterotropohs

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Linnean Taxonomy

Example: human classificationKingdom animalia

Phylum chordata

Class mammalia

Order primateFamily hominid

Genus homo

Species sapiens

Binomial nomenclature uses genus andspecies to make the scientific name

Homo sapiens

Classification activity

http://www.pbs.org/wgbh/evolution/change/family/index.html

http://www.pbs.org/wgbh/evolution/change/family/index.html

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Human Evolution

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Explore Human Evolution

View the Becoming Human broadbanddocumentary

As you view each segment, visit the related

exhibits to further explore this topicGo to the Learning Center and select the

“Calculating Cousins” activity

Go to the Learning Center and select the

“Chromosome Connection” activity Go to the Learning Center and select the

“Building Bodies” activity

http://www.becominghuman.org/




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The Order Primate

Characteristics of Primates

Strong hands and opposable thumbs

Free-moving shoulder jointForward facing eyes and stereoscopic vision

Intelligence/larger brain

Social complexity

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What Characteristics do Humans Have?

All of those of primates, plus

Upright posture and bipedal

Use of tools and technology

Advanced intelligence

Complex communication and speech

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The Steps to Human Evolution

Terrestrialization

Bipedal (Walking on all two’s)

Increased Brain Size

Civilization

Take a look at the Human family tree


http://www.pbs.org/wgbh/evolution/humans/humankind/index.html

http://www.pbs.org/wgbh/evolution/humans/humankind/index.html


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The Hominid Family

Each year new fossils are found to addto the Hominid family tree

Most fossils of early humans are foundin Africa and lower Asia

Most well understood members include

genus Australopithecus (extinct) andgenus Homo

Solve the Riddle of the Bones

http://www.pbs.org/wgbh/evolution/humans/riddle/index.html

http://www.pbs.org/wgbh/evolution/humans/riddle/index.html

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Genus Australopithecus

First human ancestor to live on theground and walk on two legs

As evidenced by the Laetoli footprints Ape-like jaw

Small brain

Short statureFound only in South and East Africa



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The Australopithecines

A. anamesis 4 MYA

A. afarensis 3.2 MYA (Finding “Lucy”)

A. africanus 2.5 MYA A. robustus 2 MYA

A. boisei 2 MYA



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Genus Homo

More modern hominids that exhibited majorevolutionary steps

Increased brain size

Use of toolsUse of fire

Use of shelter

ReligionLanguage and civilization

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Homo habilis “The Tool Man”

Approx. 2.5 MYA

Brain ½ size of modern human

First to make and usestone tools andweapons

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Homo erectus “The Upright Man”

Direct ancestor of modern humans

Widespread in Africaand Asia by 1 MYA

Evidence of use of

shelter and fire

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Homo sapiens “The Wise Man” Most likely evolved from H. erectus as early as 400,000 years ago

Greatly increased brain size Consisted of 2 groups

Neanderthal

Cro-Magnon/modern H. sapiens

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Neanderthals

Found in Neander Valley in Germany

Fossils found throughout Europe, MiddleEast, and Asia from 150,000-30,000years ago

Large bodies and brains

Evidenced painting, religion, complex

social structure “Cave man”

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Cro Magnons and Fully Modern Humans

First early modern H. sapiens appear about130,000 years ago

Thinner bones, smaller jaws, higher skull

with little or no brow ridge, and larger brainsCave art shows complex religion and culture

Lived alongside Neanderthal for several

thousand years, but eventually out-competedthem

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06. Evolution