Six Criteria of ScienceSix Criteria of Science

CConsistency :onsistency : The results of The results of observations and/or experiments are observations and/or experiments are reasonably the same when repeatedreasonably the same when repeated..

1.1. Green plants will grow towards a light source.Green plants will grow towards a light source.

2.2. Walking under a ladder will cause bad luck.Walking under a ladder will cause bad luck.

OObservability :bservability : The event or evidence The event or evidence of the event, can be observed and of the event, can be observed and explained. The observations are limited explained. The observations are limited to the basic human senses or to to the basic human senses or to extensions of the senses.extensions of the senses.

1.1. Some plants eat meat.Some plants eat meat.

2.2. Extraterrestrial beings have visited Earth.Extraterrestrial beings have visited Earth.

NNatural :atural : A natural cause (mechanism) A natural cause (mechanism) must be used to explain why or how must be used to explain why or how the event happens.the event happens.

1. 1. Green plants convert sunlight into energy.Green plants convert sunlight into energy.

2. With a rod, Moses parted the sea so his 2. With a rod, Moses parted the sea so his people could cross to the other side..people could cross to the other side..

PredictabilityPredictability : : Specific predictions Specific predictions can be used to foretell an event. can be used to foretell an event. Each prediction can be tested to Each prediction can be tested to determine if the prediction is true or determine if the prediction is true or false.false.

1.1. Without sunlight (or artificial light), green plants will Without sunlight (or artificial light), green plants will die.die.

2.2. If you are a "Scorpio", your horoscope for today is If you are a "Scorpio", your horoscope for today is “Lunar position highlights back pay, refunds and “Lunar position highlights back pay, refunds and money!!!!!"money!!!!!"

TTestability :estability : the event must be the event must be testable through the processes of testable through the processes of science, and controlled science, and controlled experimentation.experimentation.

1.1. The Bermuda Triangle causes ships and The Bermuda Triangle causes ships and planes to sink and disappear.planes to sink and disappear.

2.2. Life comes from life and cannot come from Life comes from life and cannot come from non-life.non-life.

TTentativeness :entativeness : Scientific theories are Scientific theories are changeable and correctable, even to changeable and correctable, even to the point of the theory being proven the point of the theory being proven wrong. Scientific theories have been wrong. Scientific theories have been modified and will continue to be modified and will continue to be modifiedmodified1.1. The number of human chromosomes was The number of human chromosomes was

once "known" to be 48, but is now considered once "known" to be 48, but is now considered to be 46.to be 46.

2.2. We know that the world began about 6000 We know that the world began about 6000 years ago, and nothing will change that.years ago, and nothing will change that.

Scientific Scientific MethodMethod

1.1. Observation Observation

2.2. Gather Information Gather Information

3.3. HypothesisHypothesis

4.4. ExperimentExperiment

5.5. ConclusionConclusion

ObservationObservation

Using senses to gather informationUsing senses to gather informationObservations lead to questionsObservations lead to questions

““what is the effect what is the effect of …on …?”of …on …?”

Two types of ObservationsTwo types of ObservationsQualitative:Qualitative: Uses senses to Uses senses to

describedescribe Ex: Mrs. Forsythe Ex: Mrs. Forsythe

has RedHairhas RedHair

Quantitative:Quantitative: Uses tools to take a Uses tools to take a

numerical numerical measurementmeasurement

Ex: Mrs. Forsythe is Ex: Mrs. Forsythe is 5 ft 8 in. 5 ft 8 in.

HypothesisHypothesisPredicts the answer to a questionPredicts the answer to a questionBASED ON:

Past experienceObservationsResearch

The format for writing a hypothesisThe format for writing a hypothesis

““IF . . . THEN . . .because….”IF . . . THEN . . .because….”

ExampleExample : If : If we increase the temperature we increase the temperature of the fish’s water, of the fish’s water, thenthen the breathing the breathing rate will increase rate will increase becausebecause breathing breathing rate is dependent upon temperaturerate is dependent upon temperature..

ExperimentExperiment

A Test of your hypothesisA Test of your hypothesis Experiments tests a Experiments tests a VARIABLEVARIABLE (factor that changes)(factor that changes)

Example: Example: Variable = change in breathing rateVariable = change in breathing rate

Experiments need a Experiments need a CONTROLCONTROL GROUP GROUP (to compare)(to compare)

Control GroupControl Group =breathing rate at room temp =breathing rate at room temp

Types of VariablesTypes of Variables

Dependent Variable:Dependent Variable: Is the data collected through observation and Is the data collected through observation and

measurementmeasurement

Ex: Breathing RateEx: Breathing Rate Independent Variable: Independent Variable:

Variable that is manipulated (changed) during Variable that is manipulated (changed) during the experiment.the experiment.

Ex: Water TempEx: Water Temp

ConclusionConclusion4 parts4 parts::1.1. Did the experiment support the hypothesis?Did the experiment support the hypothesis?

2.2. If you did the experiment again, what would you If you did the experiment again, what would you do differently?do differently?

3.3. What did you learn?What did you learn?

4.4. Possible ErrorsPossible Errors

Experimental Design

Activity

TheoryTheory

theorytheory = hypothesis supported by = hypothesis supported by many experiments over timemany experiments over time

Examples of theories:Examples of theories:

Big Bang TheoryBig Bang Theory

Theory of Plate TectonicsTheory of Plate Tectonics

Jean Baptiste LamarckJean Baptiste Lamarck Evolution occurs as Evolution occurs as structures develop structures develop through use, or through use, or disappear because of disappear because of disuse, and these disuse, and these

““acquired acquired characteristics”characteristics”

are passed to offspringare passed to offspring

EXAMPLE: EXAMPLE:

Over a Giraffes Lifetime it Over a Giraffes Lifetime it can stretch it’s neck and can stretch it’s neck and it’s offspring will be born it’s offspring will be born with long necks….with long necks….

Valid?Valid?

Darwin and The Monkey!Darwin and The Monkey!

THIS IS NOT WHAT HIS THEORY SAYS

Who was Charles DarwinStudied MedicineStudied Medicine

Hated the sight of Hated the sight of bloodblood

Received a BA in Received a BA in TheologyTheology

Had 10 children Had 10 children

Theory of EvolutionTheory of Evolution Darwin was an Darwin was an NaturalistNaturalist on the on the HMS HMS

BeagleBeagle In The In The Galapagos IslandsGalapagos Islands, Darwin , Darwin

collected species of finches (13)collected species of finches (13)Each had a specialized diet and way Each had a specialized diet and way

of obtaining food. of obtaining food. These finches all closely resembled a These finches all closely resembled a

South American finch speciesSouth American finch speciesHypothesized Hypothesized that the differences that the differences

were do to gradual changewere do to gradual change

Darwin’s FinchesDarwin’s Finches

Theory of EvolutionTheory of EvolutionDarwin referred to such change as Darwin referred to such change as

““descent with modification” – descent with modification” – evolution; evolution;

Wrote Origin of SpeciesHe still wondered He still wondered

““How does evolution occur?”How does evolution occur?”

After his voyage, Darwin made following After his voyage, Darwin made following inferencesinferences::

1.1. There is variation within populationsThere is variation within populations

2.2. Some variations are favorable (better)Some variations are favorable (better)

3.3. Not all young each generation can surviveNot all young each generation can survive

4.4. Individuals that survive and reproduce are Individuals that survive and reproduce are those with favorable variationsthose with favorable variations

5.5. And then those traits will increase in a And then those traits will increase in a population and population will slowly population and population will slowly changechange

Darwin called this process by which Darwin called this process by which populations change in response to populations change in response to

their environmenttheir environment

Natural SelectionNatural Selection

Evolution happens because Evolution happens because of natural selectionof natural selection

Selection acts on individuals, populations evolve

Change creates advantages Change creates advantages for some species & for some species &

disadvantages for othersdisadvantages for othersFossils reveal changes in species over Fossils reveal changes in species over

millions of yearsmillions of years

AdaptationAdaptation

Adaptations are inherited traits that Adaptations are inherited traits that increase a group’s chance of increase a group’s chance of

survival & reproductionsurvival & reproduction

This type of finch has This type of finch has a thick beak a thick beak adaptation for adaptation for

cracking open seedscracking open seeds

VariationVariationWithin a species, there is variationWithin a species, there is variation

1.1. VariationVariation = differences between = differences between members of a populationmembers of a population

2.2. SpeciesSpecies = group that can breed & = group that can breed & produce healthy offspringproduce healthy offspring

Evidence for EvolutionEvidence for Evolution1. Fossils show change over time1. Fossils show change over time

scientists can date fossils & use them to scientists can date fossils & use them to support the theory of evolutionsupport the theory of evolution

common ancestors reveal whether common ancestors reveal whether species are relatedspecies are related

– Anatomy of living species also Anatomy of living species also

shows relatednessshows relatedness

How Anatomy supports EvolutionHow Anatomy supports Evolution

2.2. Homologous StructuresHomologous Structures Traits similar in different species Traits similar in different species

because they share a common ancestorbecause they share a common ancestor ExEx: human arm, dog front limb, horse : human arm, dog front limb, horse

leg, whale finleg, whale fin

“ “ Look the Same”Look the Same”

3. Analogous structures3. Analogous structuresDistantly related species have structures that Distantly related species have structures that

have the have the same functionsame function but are different in but are different in structurestructure

ExEx: wing of butterfly & bird: wing of butterfly & bird

“ “ Work the Same”Work the Same”

4. Vestigial structures4. Vestigial structures Structures reduced in size & often Structures reduced in size & often

unusedunused Remains of functional structures Remains of functional structures

inherited from an ancestorinherited from an ancestor ExEx: leg & hip bones in pythons & : leg & hip bones in pythons &

whaleswhales

5. Molecular Evidence5. Molecular Evidence

Also called biochemical evidenceAlso called biochemical evidenceCompares biomolecules such as DNA or Compares biomolecules such as DNA or

amino acid sequences between organismsamino acid sequences between organismsRelated organisms have more of the same Related organisms have more of the same

molecules in commonmolecules in common

How Do New How Do New Species Form?Species Form?

How do new species form?How do new species form?1.1. Geographic IsolationGeographic Isolation

When members of a population are When members of a population are separated separated

ExEx: polar, grizzly, & black bears: polar, grizzly, & black bears

2. Reproductive Isolation2. Reproductive IsolationWhen members of a population can’t When members of a population can’t

breed even though they live nearbybreed even though they live nearbyExEx: different mating seasons or different : different mating seasons or different

mating callsmating calls

Different Types of EvolutionDifferent Types of Evolution

1.1. Divergent evolutionDivergent evolution

2.2. Convergent evolutionConvergent evolution

3.3. CoevolutionCoevolution

4.4. Adaptive radiationAdaptive radiation

Divergent EvolutionDivergent EvolutionIsolated populations Isolated populations evolve independentlyevolve independently

ExEx: polar & grizzly bears : polar & grizzly bears changed independently changed independently due to different habitatsdue to different habitats

Convergent EvolutionConvergent EvolutionUnrelated species become more Unrelated species become more alike because they live in similar alike because they live in similar

environmentsenvironments

ExEx: shark & dolphin: shark & dolphin

CoevolutionCoevolution

Species that interact closely adapt to one Species that interact closely adapt to one anotheranother

ExEx: flowers & hummingbirds: flowers & hummingbirds

Adaptive RadiationAdaptive Radiation

Evolution of many diverse species from Evolution of many diverse species from one common ancestorone common ancestor

ExEx: famous Galapagos finches discovered : famous Galapagos finches discovered by Darwinby Darwin

How fast does evolution How fast does evolution occur?occur?

GradualismGradualism

One species One species changes slowly & changes slowly &

eventually eventually becomes two becomes two

speciesspecies

This idea is This idea is supported by supported by

fossil evidencefossil evidence

Punctuated Punctuated EquilibriumEquilibrium

Stable with short Stable with short periods periods

of change during which of change during which a new species formsa new species forms