ReviewReviewLamarck V. DarwinLamarck V. Darwin

Theories of EvolutionTheories of Evolution

DifferencesDifferencesLamarck DarwinLamarck Darwin

Use and disuseUse and disuseOrganisms have a desire Organisms have a desire of something and can of something and can change traitschange traitsInheritance of Acquired Inheritance of Acquired TraitsTraitsTendency towards Tendency towards complexity and perfectioncomplexity and perfectionInitially not much variation Initially not much variation within a populationwithin a populationEvolution = thousands of Evolution = thousands of yearsyears

Natural SelectionNatural SelectionMutation Mutation Variation in a Variation in a population population environment selects environment selects “good” genes“good” genesCan pass on traits if Can pass on traits if mutation is in DNA of sex mutation is in DNA of sex cellscellsEvolution requires Evolution requires millions of yearsmillions of years

Use and Disuse Theory: if an organism Use and Disuse Theory: if an organism wants something badly enough wants something badly enough

(desire), it can acquire a new trait by (desire), it can acquire a new trait by use or disuse.use or disuse.

Inheritability of Acquired Traits = if an Inheritability of Acquired Traits = if an organism acquires (gets) a trait it did organism acquires (gets) a trait it did not have before, it can then pass the not have before, it can then pass the

trait on to its offspringtrait on to its offspring

Trying to answer the same question:Trying to answer the same question:

How do populations change over time?How do populations change over time?

Agree that organisms change over timeAgree that organisms change over time

Environment drives evolution of traitsEnvironment drives evolution of traits

Common descentCommon descent

SimilaritiesSimilaritiesLamarck and DarwinLamarck and Darwin

Example Lamarck Darwin

Giraffes

Long Bird Legs

Sharp Vision of Hawks

Example Lamarck Darwin

Giraffes

Wanted to reach food high in trees used neck to reach leaves long neck pass to offspring

Some giraffes already had slightly longer necks (from mutation) created variation in population environment favored longer necks long necks survived and passed on trait

Long Bird Legs

Sharp Vision of Hawks

Example Lamarck Darwin

Giraffes

Wanted to reach food high in trees used neck to reach leaves long neck pass to offspring

Some giraffes already had slightly longer necks (from mutation) created variation in population environment favored longer necks long necks survived and passed on trait

Long Bird Legs Needed to stretch legs to get food in deeper water passed on trait to offspring

There was variation in leg length of birds due to mutation environment favored longer legged birds shorter legged birds died or moved

Sharp Vision of Hawks

Example Lamarck Darwin

Giraffes

Wanted to reach food high in trees used neck to reach leaves long neck pass to offspring

Some giraffes already had slightly longer necks (from mutation) created variation in population environment favored longer necks long necks survived and passed on trait

Long Bird Legs Needed to stretch legs to get food in deeper water passed on trait to offspring

There was variation in leg length of birds due to mutation environment favored longer legged birds shorter legged birds died or moved

Sharp Vision of Hawks

Strained eyes to see prey further away passed to offspring

Some hawks had better vision able to get more prey and out compete other birds poor-visioned birds died

QuestionsQuestions

Why was Lamarck incorrect?Why was Lamarck incorrect?– Changing the phenotype does not change the Changing the phenotype does not change the

genotype.genotype.– Variation already exists in populations from mutationVariation already exists in populations from mutation

How can you pass on a trait caused from How can you pass on a trait caused from mutation?mutation?– Only if the mutation is in the DNA of the sex cells Only if the mutation is in the DNA of the sex cells

(sperm or eggs)(sperm or eggs)

HUMAN HUMAN EVOLUTIONEVOLUTION

Taxonomic ClassificationTaxonomic Classification

Kingdom: AnimaliaKingdom: AnimaliaPhylum: ChordataPhylum: ChordataClass: MammaliaClass: MammaliaOrder: PrimatesOrder: PrimatesFamily: Hominidae (Hominids)Family: Hominidae (Hominids)

Genus: Homo (humans), Pan (chimps), Genus: Homo (humans), Pan (chimps), Gorilla (gorillas)Gorilla (gorillas)

PrimatesPrimates

PrimatesPrimatesanimals with five flexible fingers with an animals with five flexible fingers with an opposable thumb opposable thumb (include monkeys, apes, and humans)(include monkeys, apes, and humans)

Have binocular and color visionHave binocular and color vision

Evolved about 35 million years agoEvolved about 35 million years ago

Human DNA and chimp DNA is 98.4% Human DNA and chimp DNA is 98.4% similar!!!similar!!!

Cladogram of Human EvolutionCladogram of Human Evolution

THE GREAT APESTHE GREAT APES

Chimpanzee Bonobo Gorilla Orangutan

Man’s Closest Living Relatives

Evolutionary Evolutionary Origins of Origins of HumansHumans

HOMINIDSHOMINIDShumans and their humans and their

closest fossil relativesclosest fossil relatives

Skulls are evidence for human evolution

A bonobo with bipedal locomotion.

“Lucy”• The oldest hominid (3 myo)

• Discovered by Johanson in 1974 in Ethiopia

• About 3.5 ft tall / 62 lbs

• Walked upright

• Evidence that hominids walked upright before they evolved larger brains

The First The First HumansHumans

The genus The genus HomoHomo evolved in evolved in Africa about 2 million years agoAfrica about 2 million years ago

Darwin’s ExplanationDarwin’s Explanation

How would Darwin explain the evolution of How would Darwin explain the evolution of humans from a monkey ancestor?humans from a monkey ancestor?– Mutations produced variability in monkey Mutations produced variability in monkey

populations populations the environment selected the environment selected those organisms that were best adapted (high those organisms that were best adapted (high fitness) fitness) over millions of years and much over millions of years and much change in the environment, humans evolved change in the environment, humans evolved because they were the best adapted to the because they were the best adapted to the environment.environment.